Spinal laser interstitial thermal therapy for treatment of chordoma: single-center experience and literature review

Abstract

Purpose

Chordomas are rare, locally aggressive tumors for which effective salvage options are limited once maximal surgical and radiation therapy have been exhausted. Laser interstitial thermal therapy (LITT) is a minimally invasive, MRI-guided ablative technique established for spinal metastases, but published experience with LITT for chordoma remains limited to isolated case reports. We report the largest clinical experience with spinal LITT (sLITT) for chordoma and review the existing literature.

Methods

We performed a retrospective, IRB-approved single-institution case series of patients with histologically confirmed chordoma treated with sLITT. Clinical, operative, and radiographic data were abstracted, including tumor volumes, ablation parameters, and functional and oncologic outcomes. A systematic PubMed search was performed to identify all prior published reports of LITT for chordoma.

Results

Four patients underwent sLITT across five procedures, treating metastatic foci from primary sacral, clival, and cervical chordomas, as well as one primary thoracic lesion. sLITT was used as salvage treatment in four procedures and as primary treatment in one patient to avoid the morbidity of open surgery. Median time from diagnosis to LITT was 19.1 months (range 2.5–168.3), and pre-operative KPS was 90–100 in all patients. A median of four laser fibers and 16 ablations were used per procedure (12–15 W). Median case duration was 352.5 min and length of stay was two days. Postoperative SRS was administered in all but one procedure. All patients experienced volumetric tumor reduction on the earliest post-operative MRI (median 4.2 months, range 2.8–8.8), with a mean reduction of 25.7% ± 12.7%. Median radiographic follow-up was 16.8 months (range 3.5–48.1). No procedure required additional intervention at the LITT-treated site, and no progression at the treated site was identified on available follow-up imaging. Median overall survival from LITT was 23.0 months. One procedure was complicated by transient radiculopathy that resolved with steroids. Literature review identified four previously published case reports of LITT for chordoma, three of which described complete thermal ablation with radiographic response; our series represents the largest reported clinical experience to date.

Conclusion

This series represents the largest reported clinical experience with LITT for chordoma and provides proof-of-concept supporting prospective evaluation of this technique. sLITT was technically feasible and well tolerated in this small chordoma cohort, applied both as salvage therapy and, in one patient, as primary local treatment. Because SRS followed all but one procedure, the independent contribution of sLITT to the radiographic responses observed cannot be determined from these data.

Introduction

Chordomas are rare, slow-growing tumors that arise from the malignant transformation of embryonic notochordal remnants [1]. They account for 1–4% of all primary bone tumors with an annual incidence of about 0.08 per 100,000 people and are most commonly diagnosed in men between 50 and 60 years [2]. Despite their histologically low-grade appearance, chordomas are locally aggressive tumors and, in a subset of patients, prone to recurrence and distant metastasis [3]. Even among patients who undergo gross total resection followed by adjuvant radiotherapy, local recurrence occurs in more than 50% of cases [4]. Local control and survival rates are significantly worse in patients with recurrent tumors despite additional treatment [5]. Once maximal safe surgical and radiation options have been exhausted, effective salvage options remain limited.

Evidence is accumulating for laser interstitial thermal therapy (LITT) for several indications across neurosurgical oncology, especially for patients in whom open resection is prohibitive [6]. Spinal LITT (sLITT) was first introduced by Tatsui et al. as a minimally invasive alternative to separation surgery [7], with subsequent prospective experience demonstrating safety and efficacy in larger cohorts with integration into multidisciplinary treatment paradigms that include stereotactic radiosurgery (SRS) [8]. This technique has since been refined and its patient selection criteria clarified, particularly for patients requiring rapid resumption of systemic therapy or those who are poor surgical candidates [9–11]. Most recently, a series of 129 patients treated with sLITT combined with radiotherapy across 144 thoracic vertebral segments, comprising predominantly radioresistant histologies such as renal cell carcinoma, sarcoma, and non-small cell lung carcinoma, demonstrated 1-year local control and overall survival of 80% and 78%, respectively [12]. Moreover, a recent systematic review demonstrated that, in select patients, sLITT combined with SRS achieves local control and survival outcomes comparable to separation surgery while reducing perioperative morbidity and enabling faster resumption of oncologic treatment [13].

Given chordoma’s predilection for spinal involvement and the limitations of repeat surgery and reirradiation in the setting of recurrent disease, sLITT may represent an attractive minimally invasive cytoreductive or decompressive strategy for select chordoma lesions. However, published experience with sLITT for chordoma remains limited to isolated case reports [14–17]. Here, we report the largest clinical experience with sLITT for chordoma and review the existing literature.

Materials and methods

Patient cohort

This is an institutional review board (IRB)-approved retrospective case series of patients with histologically confirmed chordoma treated with laser interstitial thermal therapy (LITT) at a single academic institution (The University of Texas MD Anderson Cancer Center, Houston, TX) between January 2016 and November 2025. All consecutive patients who underwent LITT for chordoma were included. No exclusion criteria were applied.

Clinical, operative, and radiographic data were abstracted from the electronic medical record. Collected variables included patient demographics, tumor characteristics, oncologic treatment history, laser ablation parameters, estimated blood loss, case duration, length of hospital stay, perioperative complications, tumor volumes, and follow-up data. Tumor burden was described using the Bilsky epidural spinal cord compression (ESCC) grade [18]. Functional status was assessed using the Karnofsky Performance Status (KPS) [19].

Two complementary radiographic endpoints were applied at the treated site. Volumetric response was defined as a reduction in segmented tumor volume on the initial postoperative MRI relative to the immediate preprocedural MRI. Freedom from local progression, which corresponds more closely to conventional endpoints in spinal oncology, was defined as the absence of radiographic progression at the treated site and the absence of any subsequent intervention directed at that site across all available follow-up imaging. Both endpoints are reported for each patient. Postoperative MRI of the treated segment was not obtained according to a standardized study protocol; imaging timing and frequency were determined by each patient’s individual oncologic care, ongoing systemic treatment, and referring providers. Tumor volumes were measured using volumetric segmentation in the Brainlab planning software (Brainlab, Feldkirchen, Germany).

Primary outcomes included perioperative complications, volumetric response and freedom from local progression at the treated site, and overall survival (OS) following LITT. Secondary outcomes included length of hospital stay, functional status, and disease status at last follow-up. Descriptive statistics were used to summarize patient demographics and outcomes. Continuous variables are reported as means ± standard deviations or medians with ranges as appropriate, and categorical variables as frequencies and percentages. No comparative statistical analyses were performed given the small sample size and descriptive nature of the study.

Patient selection

Candidacy for sLITT was determined through multidisciplinary review involving spine neurosurgery, radiation oncology, medical oncology, and diagnostic radiology at our institutional spine tumor board. Patients were considered for sLITT when local control of a spinal lesion was required and one or more of the following applied: prior surgery or radiotherapy at or adjacent to the target level rendering repeat open resection or reirradiation of high risk; anticipated morbidity of open resection judged prohibitive on the basis of age, performance status, and/or comorbidities; need to resume or initiate systemic therapy without the recovery interval required after open surgery; or patient preference for a minimally invasive approach after discussion of alternatives. Lesions were considered anatomically suitable when the epidural component was accessible by a percutaneous trajectory that avoided traversing uninvolved neural structures and when the tumor-dura interface could be visualized on the thermometry plane for real-time temperature monitoring. During the study period, all patients with chordoma considered for sLITT at multidisciplinary review proceeded to treatment; no patient was evaluated and declined for sLITT.

Surgical technique

Spinal laser interstitial thermal therapy (sLITT) procedures were performed by a single surgeon (C.E.T.) using the Visualase MRI-guided laser ablation system (Medtronic, Dublin, Ireland) inside the Brainlab intraoperative MRI suite. Details of the sLITT procedure have been previously described [7, 8, 20, 21]. Thermal monitoring was performed using real-time proton-resonance-frequency MR thermometry, with tissue damage estimated on the treatment workstation using an Arrhenius model and displayed as a color-coded overlay on coplanar anatomical images. Up to six temperature-monitoring points were placed at the interface between the epidural tumor and the dura mater, with an upper safety threshold of approximately 50 °C; the system automatically deactivates the laser when this threshold is reached, protecting the spinal cord and nerve roots. Because respiratory motion degrades the reliability of the thermal map, ablations were delivered in cycles under ventilatory arrest following preoxygenation to an SpO2 of 100%, with each cycle limited to a maximum of 100 s and ventilation resumed between cycles; the procedure was halted and ventilation immediately resumed if SpO2 fell below 94% or if the dura-interface threshold was reached. In our experience, each fiber produces a zone of thermal damage extending approximately 5 mm radially, and additional access cannulas are placed in tandem when greater craniocaudal coverage is required.

Literature review

A systematic search of PubMed was performed on August 1, 2026 to identify all published reports of LITT for the treatment of chordoma. The search strategy employed the terms: (“chordoma”) AND (“laser interstitial thermal therapy” OR “LITT”). Inclusion criteria were: (1) histologically confirmed chordoma, and (2) treatment with LITT. Case reports, case series, and cohort studies were all eligible for inclusion. Reference lists of included studies were screened to identify additional publications. Studies were excluded if LITT was not performed or if the diagnosis of chordoma was not histologically confirmed. Data extracted from included studies included patient demographics, tumor location, operative technique, perioperative outcomes, adjuvant therapies, radiographic response, and oncologic outcomes when available.

Results

Patient cohort

Table 1 summarizes patient demographics, tumor characteristics, and indications for LITT. Four patients with histologically confirmed conventional chordoma underwent LITT at our institution between January 2016 and November 2025, comprising five total procedures. Median age at time of LITT was 74.3 years (range 19.7–87.6). Primary tumor sites included the sacrum (Patient 1), clivus (Patient 2), thoracic spine (Patient 3), and cervical spine (Patient 4). Patient 4 underwent two LITT procedures at distinct spinal levels and time points, hereafter referred to as 4a (first procedure) and 4b (second procedure). Three procedures were performed for metastatic foci requiring local control (Patients 1, 2, and 4a), one as primary treatment to avoid the morbidity of open surgery (Patient 3), and one as salvage treatment for local recurrence following prior surgery, radiotherapy, and systemic treatment (Patient 4b). Median time from initial diagnosis to LITT was 19.1 months (range 2.5–168.3). Pre-operative KPS was 90–100 in all patients. Treatment histories, including all surgical, radiation, and systemic therapies relative to LITT, are summarized in a swimmer plot (Fig. 1).

Table 1.

Patient demographics, tumor characteristics, and indications for laser interstitial thermal therapy (LITT)

Patient	Histology and Primary Site	Site Treated with LITT and Indication	Prior Local Treatment at Treated Site	Time from Diagnosis to LITT (mo)	Pre-op KPS
1, 75 F	Conventional Sacral	C7, Bilsky 1B Metastatic focus requiring local control	None	168.3	100
2, 74 M	Conventional Clival	T2-3, Bilsky 3 Metastatic focus requiring local control	None	19.1	90
3, 87 M	Conventional T11	T11, Bilsky 1 C Primary treatment to avoid high morbidity from open surgery	None	2.5	100
4a, 19 M	Conventional C2-6	T10-11, Bilsky 2 Metastatic focus requiring local control	None	11.6	100
4b, 23 M	Conventional C2-6	C3-5, Bilsky 3 Local recurrence after prior intervention	Surgery, Radiotherapy	56.2	100

Age is reported at the time of the index LITT procedure. Patient 4 underwent two LITT procedures at distinct spinal levels and time points, denoted 4a (first procedure) and 4b (second procedure). Bilsky grade denotes epidural spinal cord compression at the site treated with LITT. KPS, Karnofsky Performance Status

Fig. 1.

Swimmer plot depicting the treatment course of four patients (five procedures) with chordoma treated with laser interstitial thermal therapy (LITT), including diagnosis, surgery, radiotherapy, systemic therapy, and disease status relative to the date of first LITT (time 0). An axis break denotes a compressed interval in Patient 1’s extended pre-treatment history

Procedural details

Table 2 summarizes procedural details of performed LITT procedures. A median of four laser fibers (range 3–6) were used per procedure, with a median of 16 ablations (range 10–30) delivered between 12 and 15 W (Table 2). Median case duration was 352.5 min (range 335–407; not recorded for Patient 1). Median length of hospital stay was 2 days (range 1–4). Post-operative SRS was administered in all but one procedure (Patient 4b), at a median of 7.5 days (range 2–15) after LITT. Patient 1 additionally received 27 Gy in 3 fractions to a separate, non-LITT-treated site (T3-4) as part of the same treatment course. One procedure (Patient 4b) was complicated by transient proximal upper extremity radiculopathy that resolved with a short course of steroids by the 1-month follow-up visit. No other perioperative complications occurred, and there was no procedure-related mortality.

Table 2.

Procedural details of laser interstitial thermal therapy (LITT) procedures, including pre-operative tumor volume, laser ablation parameters, case duration, length of hospital stay (LOS), postoperative stereotactic radiosurgery (SRS) parameters and timing, and perioperative complications

Patient	Pre-op Tumor Volume (cc)	Laser Parameters	Case Duration (min)	LOS (d)	Post-op SRS	Complications
1	7.3	4 fibers 16 ablations at 15 W (24 min)	Not recorded	1	24 Gy in 1 Fx on POD 15	None
2	10.6	6 fibers 30 ablations at 15 W (45 min)	407	2	24 Gy in 1 Fx on POD 5	None
3	30.7	4 fibers 11 ablations at 14.25–14.55 W (15.8 min)	354	2	24 Gy in 1 Fx on POD 10	None
4a	32.9	5 fibers 20 ablations at 12–14.55 W (21 min)	335	4	24 Gy in 1 Fx on POD 2	None
4b	38	3 fibers 10 ablations at 14.55 W (8.6 min)	351	4	Not performed	Radiculopathy

POD, postoperative day

Oncologic outcomes

Table 3 summarizes oncologic outcomes following LITT. Pre-operative tumor volumes ranged from 7.3 to 38 cc. All patients experienced volumetric tumor reduction on the earliest available post-operative MRI (median 4.2 months, range 2.8–8.8), with a mean reduction of 25.7% ± 12.7% (range 6.1–36.8%). KPS at 3-month follow-up remained at baseline in all patients (90–100). No procedure required additional intervention at the LITT-treated site during follow-up. Except for Patient 3, all procedures were followed by intervention for disease elsewhere: systemic therapy initiation at 2, 38, and 98 days (pembrolizumab, cetuximab, and FAZ053 for Patients 4b, 4a, and 2, respectively), and surgical resection of a recurrent pelvic mass unrelated to the treated site at 518 days (Patient 1). At last follow-up, two patients were deceased (Patients 1 and 2, at 34.8 and 11.0 months from LITT, respectively) and two remained alive (Patient 3 at 23.0 months, and Patient 4 at 49.6 and 5.0 months from his first and second procedures, respectively), for a median overall survival of 23.0 months from LITT.

Table 3.

Oncologic outcomes following laser interstitial thermal therapy (LITT), including volumetric response, progression at the treated site, time to next intervention, functional status at 3 months, disease status, and overall survival (OS) from LITT

Patient	Volumetric Response on Initial Post-op MRI (%)	Time from LITT to Last MRI (mo)	Progression at Treated Site on Last MRI	Distal Progression at Last Restaging	Time from LITT to Next Intervention (d)	KPS at 3 mo	Disease Status	OS from LITT (mo)
1	20.2% at 2.8 mo	16.8	No	Pelvis	518	100	Deceased	34.8
2	36.8% at 4.2 mo	6.6	No	C-spine	98	90	Deceased	11.0
3	30.0% at 8.8 mo	22.8	No	No	None	100	Alive	23.0
4a	35.3% at 4.3 mo	48.1	No	C1-2, T4, lungs, spleen	38	100	Alive	49.6
4b	6.1% at 3.5 mo	3.5	Not assessed	C1-2, T4, lungs, spleen	2	100	Alive	5.0

Patient 4 underwent two LITT procedures at distinct spinal levels and time points (4a, 4b); OS for each procedure is calculated independently from its respective LITT date, and disease status reflects the patient’s status at last follow-up for both rows. Volumetric response and freedom from progression at the treated site are reported separately; see Methods for definitions. For Patient 4b, the initial postoperative MRI represents the most recent available imaging, precluding assessment of progression beyond this timepoint. Distal progression, assessed on concurrent restaging imaging (MRI and/or body CT), is reported separately to distinguish findings at the treated site from overall disease trajectory

Beyond the initial postoperative assessment, no radiographic progression at the LITT-treated site was identified in the four procedures with restaging imaging beyond the initial postoperative scan (median 19.8 months, range 6.6–48.1). Patient 3’s T11 lesion, treated with sLITT as primary therapy, showed no progression through 22.8 months, and Patient 4a’s T10-11 lesion through 48.1 months, the longest radiographic follow-up in this series. Durability beyond the initial postoperative scan could not be assessed for Patient 4b, whose first postoperative MRI is also the most recent available study. Over the same interval, distal disease progression was identified in all but one patient (Patient 3), involving the pelvis (Patient 1), cervical spine (Patient 2), and multifocal osseous and visceral sites including C1-2, T4, lungs, and spleen (Patient 4).

Literature review

Our systematic PubMed search identified three results. All three met inclusion criteria after title, abstract, and full-text screening. One additional study was identified through screening of reference lists. All four included reports were single-patient case reports or illustrative cases; no case series or cohort studies specifically addressing LITT for chordoma were identified. Results are summarized in Table 4. Reported LITT approaches included endoscopic endonasal, percutaneous translaminar, and transcranial catheter placement, reflecting the anatomic diversity of chordoma across the clivus and spine. Three of four reports described complete thermal ablation with radiographic response on follow-up imaging; one report did not include chordoma-specific procedural or outcome data. No major complications were reported across the four cases.

Table 4.

Summary of previously published reports of laser interstitial thermal therapy (LITT) for chordoma and the present series, including operative details and reported outcomes

Reference	Patient Summary	Operative Details	LOS	Complications	Outcomes
Barrese Ref [14]	54 F, clival chordoma	Endoscopic endonasal catheter placement 1 fiber 4 ablations at 12 W (5.2 min)	1	None	79% volumetric reduction at 4.5 mo
Williams Ref [15]	75 F, recurrent sacral chordoma C7 metastasis	Percutaneous catheter placement 4 fibers 16 ablations at 15 W (24 min)	1	None	20.2% volumetric reduction at 2.8 mo No progression at treated site through 16.8 mo OS 34.8 mo
Hong Ref [16]	57 M, recurrent clival chordoma	NR	NR	NR	NR
Chow Ref [17]	63 M, recurrent clival chordoma	Transcranial catheter placement 1 fiber 3 ablations at 7.5–12.15 W (5.7 min)	1	None	Radiographic stability at 3 mo Disease progression at 10 mo requiring surgery
Present series
Patient 1	75 F, recurrent sacral chordoma C7 metastasis	Percutaneous catheter placement 4 fibers 16 ablations at 15 W (24 min)	1	None	20.2% volumetric reduction at 2.8 mo No progression at treated site through 16.8 mo OS 34.8 mo
Patient 2	74 M, recurrent clival chordoma T2-3 metastasis	Percutaneous catheter placement 6 fibers 30 ablations at 15 W (45 min)	2	None	36.8% volumetric reduction at 4.2 mo No progression at treated site through 6.6 mo OS 11.0 mo
Patient 3	87 M, T11 chordoma	Percutaneous catheter placement 4 fibers 11 ablations at 14.25–14.55 W (15.8 min)	2	None	30.0% volumetric reduction at 8.8 mo No progression at treated site through 22.8 mo Alive at 23.0 mo
Patient 4a	19 M, recurrent C2-6 chordoma T10-11 metastasis	Percutaneous catheter placement 5 fibers 20 ablations at 12–14.55 W (21 min)	4	None	35.3% volumetric reduction at 4.3 mo No progression at treated site through 48.1 mo Alive at 49.6 mo
Patient 4b	23 M, recurrent C2-6 chordoma	Percutaneous catheter placement 3 fibers 10 ablations at 14.55 W (8.6 min)	4	Radiculopathy	6.1% volumetric reduction at 3.5 mo Alive at 5.0 mo

The case reported by Williams et al. is the index LITT procedure for Patient 1 in the present series; procedural and outcome data for this case were re-abstracted from the primary record and may differ from the values in the original report. POD, postoperative day; LOS, length of stay; Fx, fractions; OS, overall survival; NR, not reported

Representative cases

Two representative cases illustrating the range of clinical applications for sLITT in chordoma are presented. Figure 2 depicts Patient 3, who underwent sLITT as primary treatment for a T11 lesion to avoid the morbidity of open surgery, with pre- and post-operative MRI demonstrating volumetric tumor reduction. Figure 3 depicts Patient 4’s second procedure, in which sLITT was used as salvage treatment for recurrent cervical chordoma following prior surgery, radiotherapy, and systemic treatment. Figure 4 illustrates the corresponding intraoperative setup for this procedure, including patient positioning, stereotactic registration, and preoperative trajectory planning.

Fig. 2.

Representative case of laser interstitial thermal therapy (LITT) as primary treatment for thoracic spine chordoma (Patient 3). Pre- (A, B) and post-operative (C, D) MRI demonstrating volumetric tumor reduction. (E) Intraoperative thermal mapping demonstrating the ablation zone with corresponding temperature measurements at the tumor-spinal cord interface

Fig. 3.

Representative case of laser interstitial thermal therapy (LITT) as salvage treatment for recurrent cervical spine chordoma following prior surgery, radiotherapy, and systemic therapy (Patient 4b). Pre- (A, B) and post-operative (C, D) MRI demonstrating volumetric tumor reduction; arrow in (B) indicates the epidural tumor at the tumor-spinal cord interface. (E) Intraoperative thermal mapping demonstrating the ablation zone with corresponding temperature measurements at the tumor-spinal cord interface

Fig. 4.

Intraoperative setup of salvage cervical spine laser interstitial thermal therapy (LITT) for Patient 4b. (A–C) Photographs demonstrating patient positioning, fiducial marker placement, and stereotactic reference frame fixation for intraoperative MRI-guided navigation. (D) Preoperative trajectory planning image demonstrating the planned laser fiber trajectories targeting the epidural tumor at C3-5

Discussion

We present the largest reported clinical experience with LITT for chordoma, comprising four patients treated across five procedures. LITT was technically feasible at all treated levels, including the cervical and thoracic spine with their epidural extensions. Volumetric tumor reduction was observed in every case, with a favorable perioperative safety profile and preservation of functional status. By the more conventional oncologic endpoint of freedom from local progression (absence of radiographic progression or re-intervention at the treated site) [12], no treated site progressed or required further intervention during available follow-up, including three procedures followed beyond one year. We have deliberately not compared these observations against historical benchmarks for conventionally treated mobile spine chordoma [4] or against contemporary sLITT outcomes series [12]: with five procedures, heterogeneous lesion locations and treatment histories, and differing endpoint definitions, direct comparisons are difficult to interpret. Still, our series illustrates the range of clinical settings in which LITT has been applied, as a salvage strategy in heavily pretreated recurrent disease (Patient 4) and, in one patient, as a primary local treatment selected specifically to avoid the morbidity of open surgery (Patient 3). Taken together, these findings indicate that sLITT is technically feasible and well tolerated in a small chordoma cohort. Efficacy has not been demonstrated, and the results should not be read as evidence that LITT is equivalent or preferable to established local therapies for this disease.

LITT for chordoma: existing literature

Prior published experience with LITT for chordoma has been limited to four cases across four reports (Table 4). Barrese et al. described the first application, using an endoscopic endonasal approach to ablate a clival chordoma as primary treatment, with a 79% volumetric reduction at 4.5 months; the authors observed an ablation plateau at approximately 60 s of activation, which they interpreted as possible thermal sensitivity of chordoma [14]. This is a single-case observation without a comparator histology treated under equivalent parameters, and should be regarded as hypothesis-generating rather than as an established property of the tumor. This case and Patient 3 in our series represent the only two reported uses of LITT as a primary treatment modality for chordoma, in contrast to the salvage role described in the remaining reports. Two cases are insufficient to define a frontline role, and primary use of LITT for chordoma should at present be regarded as investigational.

Williams et al. reported the first spinal application, treating a C7 metastasis from a sacral chordoma with subsequent SRS; this work represents Patient 1 in Table 1 and highlights prior efforts at sLITT at our institution [15]. This work addressed two theoretical concerns specific to chordoma ablation. First, chordoma’s characteristic lipid-rich composition, attributable to its physaliferous tumor cell morphology, was hypothesized to decrease heat conduction relative to other tumor types historically targeted for LITT; this contrasts with the high extracellular water content otherwise attributed to chordoma’s stromal matrix, illustrating some uncertainty regarding the tumor’s net thermal conductive properties. However, intraoperative thermography demonstrated spherical ablation zones of 14–16 mm in axial diameter at each fiber tip, comparable to ablation dimensions achieved in other tumor histologies, suggesting that this theoretical limitation was not clinically significant. Second, given chordoma’s well-established propensity for tract seeding following biopsy or resection, the authors raised the possibility that an analogous risk could apply to the percutaneous LITT trajectory; this risk was mitigated using an outer access cannula, a component of standard sLITT technique originally intended to maintain fiber trajectory [7], to isolate the tract from direct tumor contact. No evidence of tract seeding was observed on follow-up imaging.

Chow et al. described transcranial LITT for a recurrent clival chordoma with subtemporal extension, which palliated the lesion for approximately 10 months before surgery was required [17]. Finally, Hong et al. included a single patient treated with LITT for a fourth clival recurrence within a larger series [16]. While chordoma-specific procedural details and outcomes were not reported, the authors’ broader experience across 95 recurrences in 40 patients led them to conclude that LITT and systemic therapy warrant consideration for patients with multiple recurrences. Our series more than doubles the aggregate published experience and, importantly, is the first to report volumetric outcomes and local control rates systematically across multiple patients.

Salvage treatment options for recurrent chordoma

sLITT should be positioned alongside, rather than in place of, established treatment options for recurrent chordoma, each of which carries a distinct risk-benefit profile. Repeat resection remains the most definitive local therapy, but local control after salvage surgery for recurrent disease is worse than after primary resection – 79% versus 86% at 5 years in one large single-institution sacral series [5]. Moreover, reoperation within a previously operated and often irradiated field carries additive risk: deep infection occurred in 50% of patients undergoing surgery for recurrent disease versus 32% for primary disease, with the large majority in both groups requiring further surgical intervention (90% and 87%, respectively). Reirradiation can achieve meaningful disease control in recurrent chordoma, but outcomes vary substantially by modality and series: 2-year local control of 85% has been reported after proton reirradiation in a small cohort of 16 patients [22], while a larger carbon-ion series found local progression-free survival (LPFS) specifically in recurrent disease to be markedly lower than in primary disease (2- and 4-year LPFS of 45% and 34% versus 83% and 66%, respectively) [23]. Reirradiation is further constrained by cumulative dose to nearby organs at risk [4]. Systemic therapy has a defined but modest role for advanced chordoma: a recent pooled analysis of 328 patients across 12 phase 2 trials reported an objective response rate of 4.7% and median progression-free survival of 10.8 months [24]. Current NCCN guidelines recommend multidisciplinary evaluation for recurrent chordoma, incorporating surgical, radiotherapeutic, and systemic options based on resectability and prior treatment [25].

Against this background, the potential niche for sLITT is narrow and specific: local cytoreduction and epidural decompression in a patient whose target lesion sits in a previously operated or irradiated field, whose systemic disease requires prompt resumption of medical therapy, and/or in whom the morbidity of open surgery is judged prohibitive. While it offers a short hospital stay and rapid return to systemic therapy, sLITT does not achieve cytoreduction comparable to resection, requires intraoperative MRI capability and specific expertise, and has no evidence base in chordoma beyond the cases described here and in Table 4. At present, it should not displace repeat resection or particle therapy where either is feasible.

Biological rationale and technical considerations

The mechanistic considerations discussed in this section are hypotheses generated by our observations and by prior reports, not mechanisms demonstrated by the present data; no tissue, dosimetric, or immunologic correlates were collected in this series. Chordomas possess several histological features that have been proposed to influence their response to thermal ablation. Their characteristic myxoid extracellular matrix and low vascularity may theoretically facilitate predictable heat deposition and reduce the heat-sink effect that can limit ablation of highly perfused tumors [14], though this must be weighed against chordoma’s lipid-rich physaliferous tumor cell composition, which has been hypothesized to have an opposing effect on thermal conductivity [15]. Formal characterization of chordoma’s thermal conductive properties would require ex vivo dosimetric study with systematic comparison against other histologies ablated under equivalent parameters as they remain incompletely understood. Nevertheless, in our series, volumetric tumor reduction was observed across all treated lesions, an observation consistent with chordoma being amenable to thermal ablation. Ablation was achieved with reproducible parameters (12–15 W) and real-time MRI thermometry, allowing continuous monitoring of the tumor-spinal cord interface to mitigate the risk of thermal injury. The single neurological complication (transient radiculopathy that resolved with steroids) underscores both the proximity of these lesions to neural structures and the recoverability of such events with appropriate monitoring.

Recent studies have shown that chordoma exhibits an “immune-excluded” phenotype in which effector immune cells are physically sequestered from tumor cells by dense stromal septa [26]. This immunosuppressive microenvironment offers one possible explanation for the limited and transient responses to systemic and immunotherapy observed in our cohort’s most heavily pretreated patient (Patient 4). Beyond its cytoreductive effect, LITT-induced hyperthermia has also been proposed as a platform for immune modulation rather than merely a means of tumor destruction: the graded thermal injury produced by LITT promotes release of damage-associated molecular patterns, immune cell activation, and transient blood-brain barrier disruption, potentially converting immunologically “cold” tumors into more immunogenic, “hot” phenotypes and enhancing delivery of subsequent immunotherapy [27]. Whether an analogous mechanism could help overcome chordoma’s stromal immune exclusion remains entirely untested. We present it as a hypothesis for future investigation, not as a finding of this study or as a rationale for current clinical decision-making.

LITT within a multimodal paradigm

An important consideration in interpreting our results is that SRS was administered after all but one procedure, consistent with the established sLITT-plus-SRS paradigm for spinal metastases [8]. This raises the question of whether local control should be attributed to LITT, SRS, or their combination. Several observations are consistent with an independent contribution from LITT. First, the one procedure not followed by SRS (Patient 4b) nonetheless demonstrated volumetric reduction. Second, SRS was delivered early (median 7.5 days post-LITT), yet volumetric reduction was already evident on imaging obtained as early as 2.8 months, a timeframe in which the ablative effect of LITT, rather than the slower radiobiological response to SRS, is the more plausible driver of early treatment response. This is consistent with prior sLITT series demonstrating significant epidural decompression as early as 2 months post-procedure, preceding the expected timeframe for radiobiological response to SRS [7]. Independent systematic review data corroborate this pattern, with reduced epidural compression documented as early as 30 days post-ablation across published sLITT series, further supporting an early and independent ablative contribution from LITT itself [13]. This is additionally supported by a recent large single-institution series of 129 patients (144 thoracic segments), in which patients treated with sLITT alone as standalone salvage therapy, without any adjuvant radiotherapy, achieved a 1-year freedom from local failure of 83.4%, statistically similar to the 79.2% observed in patients who received adjuvant radiotherapy (p = 0.88) [12]. This suggests that sLITT may confer local tumor control independent of subsequent radiation, although that cohort comprised metastatic epidural disease of other histologies and its findings cannot be assumed to extend to chordoma.

Taken together, the observations in this study are suggestive but not conclusive. SRS followed four of five procedures at a median of 7.5 days, and no feature of this retrospective design permits the effect of sLITT to be separated from that of subsequent radiation. We therefore interpret the radiographic responses reported here as attributable to the sLITT-plus-SRS combination – analogous to the way separation surgery plus SRS is evaluated as a unified strategy – rather than to sLITT alone. Within this framework, LITT plausibly serves a cytoreductive and decompressive role that reduces epidural tumor burden and may enable safer radiation delivery in chordoma, but its independent clinical contribution remains undetermined.

Limitations

This study has several limitations inherent to a small, retrospective, single-institution case series. The sample size precludes formal survival analysis or statistical comparison, and outcomes are reported descriptively. Follow-up duration was heterogeneous, and the earliest post-operative MRI was obtained beyond three months in one patient. The concurrent use of SRS limits attribution of local control to LITT alone. Although Patient 4a showed no progression at the T10-11 site through 48 months, the longest radiographic follow-up in this series, this should be interpreted alongside the concurrent distal progression observed across the cohort; site-specific stability in the setting of multifocal systemic progression is of uncertain clinical significance. The heterogeneity of tumor locations and treatment histories limits any generalizable conclusion about efficacy in a given clinical scenario. Selection bias is inherent to the design: patients were chosen for sLITT through multidisciplinary review on the basis of favorable anatomy, adequate performance status, and unsuitability for open resection, and the outcomes reported here cannot be extrapolated to unselected patients with spinal chordoma. All procedures were performed by a single surgeon at a center with intraoperative MRI capability and substantial prior sLITT experience, which limits generalizability to other settings. Patient-reported outcomes, including validated pain and quality-of-life instruments, were not collected. Given all of the above, our findings should be understood as establishing technical feasibility and short-term tolerability, not safety or efficacy in any statistical sense, and as providing a foundation for prospective investigation.

Future directions

Given the rarity of chordoma and the limitations of repeat surgery and reirradiation in recurrent disease, minimally invasive local control strategies such as LITT warrant continued investigation across the full spectrum of disease presentation, from primary to multiply recurrent salvage treatment. Our experience supports the design of a prospective study evaluating LITT for chordoma with standardized imaging follow-up, controlled timing of adjuvant radiation, and predefined local control and functional endpoints. Such a study could build on established decision frameworks already used to guide sLITT patient selection in the broader spinal metastasis population, such as the neurologic, oncologic, mechanical, and systemic (NOMS) framework [28]. In particular, given the limited existing experience with LITT as a primary treatment modality, future prospective work should specifically evaluate patient selection criteria for frontline use, including tumor size, location, and surgical morbidity risk, to better define which patients may benefit from LITT as an alternative to open resection at initial diagnosis rather than solely as a salvage strategy. This would help clarify the independent contribution of LITT, define optimal patient selection, and establish whether the radiographic responses observed in this series can be replicated in a larger cohort. An additional area for future investigation relates to chordoma’s immune-excluded microenvironment [26]. Given evidence that LITT-induced hyperthermia can transiently modulate blood-brain barrier permeability and potentiate response to immunotherapy in other tumor types [27], whether LITT could similarly help overcome chordoma’s stromal immune barrier and enhance immune-based therapy warrants investigation.

Conclusion

We present the largest reported clinical experience with LITT for chordoma. Across four patients and five procedures, LITT was technically feasible at cervical and thoracic levels, was well tolerated, and was followed by volumetric tumor reduction with preservation of functional status. No procedure required subsequent intervention at the treated site during available follow-up. Because SRS followed all but one procedure, these data cannot establish an independent treatment effect of LITT, and the observations reported here demonstrate feasibility rather than efficacy. They provide proof-of-concept supporting prospective evaluation of LITT in this rare and challenging tumor, particularly for patients in whom repeat surgery and reirradiation options have been exhausted.

Author contributions

C.E.T. conceived the study. S.V.J. designed the review, performed the literature search, and acquired and analyzed clinical data. S.V.J. prepared all tables and figures. J.W.C., K.W., and A.R.F. contributed to data acquisition and manuscript revision. A.J.G., G.K., R.Y.N., C.A.A.B., and L.D.R. provided clinical oversight and critically revised the manuscript. C.E.T. supervised the project. S.V.J. drafted the manuscript with contributions from all authors. All authors critically revised the manuscript and approved the final version.

Funding

None.

Data availability

The data that support the findings of this study are not publicly available due to patient privacy and institutional data protection requirements. De-identified data may be made available from the corresponding author upon reasonable request and with appropriate institutional approval.

Declarations

Competing interests

The authors declare no competing interests.