Limb-sparing surgery combined with local inactivation by ablation improves local control in soft-tissue sarcomas

Abstract

Aims

Soft-tissue sarcoma (STS) is a rare, aggressive malignancy with a high risk of recurrence when invading surrounding structures, and the optimal treatment strategy for safe surgical margins is still unclear. This study aimed to evaluate the safety and efficacy of combined local inactivation by ablation in STS during limb-sparing surgery in high-risk STS patients.

Methods

A retrospective cohort study was conducted on 44 patients between 1 January 2018 and 31 December 2022, at a tertiary medical centre. The patients were divided into two groups based on whether combined microwave in situ ablation (MWA) was performed during surgery (MWA group, n = 24 vs Control group, n = 20). The two groups were compared for postoperative complications, local disease-free survival (DFS), overall survival (OS), and progression-free survival (PFS).

Results

At the last follow-up, 12 patients in the Control group and eight patients in the MWA group experienced local recurrence. The MWA group showed longer local DFS than the Control group (48.02 (SD 4.70), 95% CI 38.81 to 57.23 vs 33.91 (SD 6.54), 95% CI 21.10 to 46.71; p = 0.047). Postoperative complications showed no significant difference (MWA: 33.3% vs Control 25%, p = 0.143). No significant differences were observed in the median OS (MWA: 53.10 (SD 6.91), 95% CI 39.55 to 66.75) compared with Control (58.30 (SD 4.66), 95% CI 49.16 to 67.44; p = 0.512) and median PFS (MWA: 16.67 (SD 3.75), 95% CI 9.32 to 23.97) compared with Control (12.62 (SD 5.88), 95% CI 1.10 to 24.09; p = 0.691) between the two groups.

Conclusion

The combined in situ ablation inactivation in high-risk STS during limb-sparing surgery can improve local tumour control and prolong local disease-free survival.

Cite this article: Bone Jt Open 2025;6(9):1129–1137.

Introduction

Soft-tissue sarcomas (STS) are rare malignant tumours originating from mesodermal heterogeneity, primarily occurring in the limbs, trunk, and retroperitoneum, with approximately 1% of malignant tumours and 13,500 new cases of STS diagnosed each year in the USA.^1,2

Oncological surgeons have long focused on enhancing limb salvage and local control rates, primarily relying on a multidisciplinary approach, combining surgery, radiation therapy, and/or chemotherapy.^3-9 Risk factors for high-risk soft-tissue sarcomas include tumour size, location, grade, histological type, as well as margin status.^3,5-9 Limb-sparing surgical resection for STS remains a substantial challenge for surgeons.¹⁰ Reportedly, when tumours breach normal compartmental anatomy, or invade surrounding structures such as bone, the complexity of surgery increases markedly, contributing to the high recurrence rates. Moreover, amputation may result in lower local recurrence rates, but it does not offer overall survival benefits and instead causes irreversible functional impairment.¹¹

Traditionally anchored by anthracycline-based chemotherapy and radiotherapy, the landscape of STS treatment has not shifted dramatically in the past 20 years.^8,12 In recent years, microwave ablation (MWA) has been reported in the treatment of various advanced malignancies, including osteosarcoma, hepatocellular carcinoma, and bone and soft-tissue sarcoma.^13-18 This therapeutic approach utilizes the thermal effects of electromagnetic waves to induce cell destruction, offering particular benefits in tissues with low conductivity and high impedance, like bone tissue, as well as in tissues with high water content, such as solid tumours and organs. Previous studies reported using ablation techniques to locally inactivate the tumour lesion and its margins can improve tumour local control and progression-free survival.^16-18

This study aims to investigate the safety and effectiveness of limb-sparing surgery with/without MWA ablation in high-risk STS patients, focusing on their potential benefits from in situ ablation technology.

Methods

We collected data retrospectively from patients diagnosed with soft-tissue sarcoma who were treated at Guangdong Provincial People’s Hospital, a tertiary medical institution, from 1 January 2018 to 31 December 2022. This study was approved by the hospital’s Ethics Committee (XJS2022-101-01), and all patients provided written informed consent. The study was retrospectively registered on ClinicalTrials.gov (NCT06802510). The flowchart of patient enrolment and exclusion is presented in Figure 1. The patients were divided into two groups (MWA and control group). The MWA group received surgical resection combined with local lesion inactivation by MWA, while the Control group underwent standard surgical resection alone. Non-specified sarcomas are treated with the doxorubicin and ifosfamide (AI) chemotherapy regimen, while soft-tissue Ewing’s sarcoma is treated with the standard recommended vincristine, doxorubicin, and cyclophosphamide (VDC)/ifosfamide and etoposide (IE) chemotherapy regimen.^8,19 The AI regimen consisted of doxorubicin (37.5 mg/m², intravenous (IV), days one to two) and ifosfamide (2,500 mg/m², IV over three hours, days one to three), with mesna for uroprotection. The VDC regimen included vincristine at 1.4 mg/m² (maximum 2 mg) IV on day one, doxorubicin at 75 mg/m² IV over days one and two, and cyclophosphamide at 1,200 mg/m² IV on day one, with mesna for bladder protection. The IE regimen consisted of ifosfamide at 1,800 mg/m²/day IV over days one to five, accompanied by mesna, and etoposide at 100 mg/m²/day IV over days one to five. Typically, patients undergo 14 cycles (seven VDC and seven IE), with surgery scheduled after the sixth cycle. The specific treatment plan was determined based on multidisciplinary discussions involving oncology, orthopaedic oncology, and pathology departments, as well as the patient’s personal preferences. Each cycle was supported with granulocyte colony-stimulating factor (G-CSF) to aid blood cell recovery. All patients received neoadjuvant chemotherapy, and adjuvant radiotherapy/chemotherapy was administered postoperatively.

Fig. 1.

Flowchart of patient enrolment and exclusion. MWA, microwave ablation.

Inclusion criteria

1. Pathologically confirmed high-grade soft-tissue sarcoma (Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) grade G2-G3).²⁰

2. Patients with Eastern Cooperative Oncology Group (ECOG)²¹ performance status 0 to 2 and no major comorbidities, including cachexia, severe cardiopulmonary dysfunction, and other significant health conditions.

3. MRI/CT confirmed tumour invasion beyond anatomical compartments, joint involvement, or encroachment on surrounding tissues (bones, muscle, etc).

4. After being fully informed of the risks, the patient strongly refuses amputation or wide resection, which leads to irreversible impaired function.

Exclusion criteria

1. Patients with soft-tissue sarcomas limited to one compartment.

2. Distant metastasis at the time of initial diagnosis.

3. Missing clinical or follow-up data.

Patient characteristics

The study admitted 166 patients and a total of 44 were included, with 20 in the Control group and 24 in the MWA group. The clinical characteristics are presented in Table I.

Table I.

Clinical characteristics between the two groups.

Characteristic	Control group (n = 20)	MWA group (n = 24)	p-value
Sex (male/female), n	13/7	14/10
Mean age, yrs (SD)	36.6 (21.6)	40.21 (17.0)	0.813*
≤ 50 yrs, n (%)	14 (70)	16 (66.7)
> 50 yrs, n (%)	6 (30)	8 (33.3)
MWA, mins	-	5 to 40
MWA, W	-	35 to 100
Tumour size, n (%)			0.743†
≤ 5 cm	5 (25)	5 (20.8)
> 5 cm	15 (75)	19 (79.2)
Primary site, n (%)
Limbs	12 (60)	16 (66.7)
Trunk	5 (25)	5 (20.8)
Pelvis	3 (15)	3 (12.5)
Chemotherapy (no/yes), n	3/17	2/22	0.488‡
Radiotherapy (no/yes), n	10/10	16/8	0.263†
FNCLCC grade, n (%)			0.045‡
G2	5 (25)	1 (4.2)
G3	15 (75)	23 (95.8)
Median OS, mths	58.30 (40.0 to 62.0)	53.10 (43.4 to 64.6)

^*Independent-samples t-test.

^†Chi-squared test.

^‡Fisher’s exact test.

FNCLCC, Fédération Nationale des Centres de Lutte Contre le Cancer; MWA, microwave ablation; OS, overall survival.

Surgical procedures

The surgical position was determined based on the tumour’s location, and a curved incision was usually made. A typical case is presented in Figure 2 and Figure 3. The surgical procedure followed a standardized protocol as outlined below:

Fig. 2.

A 52-year-old male with spindle cell sarcoma in the left leg. a) T2-weighted MRI images demonstrating a large tumour encasing the fibula in the lower leg, with extensive mucinous necrosis and invasion into the tibia. b) Intraoperative images showing insertion of the ablation antenna for tumour ablation after anatomical dissection and tumour exposure. c) Sarcoma after local inactivation by ablation. d) After tumour resection, drilling, and insertion of ablation needles for tibial inactivation.

Fig. 3.

Schematic illustration of the surgical workflow: tumour mapping, tumour local inactivation, invasive region inactivation, and bone inactivation. Yellow indicates the sarcoma, while grey represents the inactivated areas. MWA, microwave ablation.

Tumour mapping and ablation planning: The ablation zone was carefully defined using contrast-enhanced T2-weighted MRI and diffusion-weighted imaging (DWI) to identify the tumour margins, including the tumour oedema zone. The multidisciplinary team, including radiologists, guided the tumour mapping, utilizing 3D imaging reconstruction to visualize the tumour’s precise position, size, and relationship to surrounding tissues. The ablation area was extended 2 cm to 3 cm beyond the tumour to account for potential microscopic invasion.

Incision and biopsy track: The skin and subcutaneous fat were dissected down to the deep fascia. The biopsy track, designed preoperatively, was removed together during the surgery.

Tumour ablation inactivation process: In situ MWA was performed in a gradual, step-by-step manner, starting from the shallow tissue and progressing deeper. Multiple ablation antennae (Microwave Ablation System; VISON Medical), placed at 1.5 cm intervals, formed a microwave matrix to ensure comprehensive tumour inactivation. The ablation time and power were adjusted based on the lesion size, maintaining the temperature within the ablation zone between 70°C to 80°C. A continuous drip of ice-cold saline was used to protect surrounding tissues, with thermometers ensuring their temperature remained below 40°C to 43°C. When the tumour mass is large, achieving complete ablation becomes difficult. The approach is to perform in situ ablation and deactivation treatment along the tumour boundary and an additional 2 cm to 3 cm margin to ensure negative surgical margins. When performing ablation of weightbearing bones in the lower limbs, additional internal fixation is necessary to mitigate the increased risk of bone fragility following the procedure. Note, that additional ablation after resection can be supplemented, which is a flexible decision. For example, in the typical case (Figure 2), the principle followed was to first ablate, then remove the tumour, and then ablation inactivate the suspected invading bone section, which was due to anatomical limitations. When the lesion invaded the bone, our experience was to drill holes at 1 cm to 1.5 cm intervals and gradually insert the ablation needles from both the distal and proximal ends to inactivate the bone (Figure 2d).

Tumour and necrotic tissue removal: After ablation, the tumour and necrotic tissue were excised. Frozen pathology was taken from the cutting edge to confirm negative surgical margins. In cases where the tumour was adjacent to or involved blood vessels or nerves, microsurgical dissection of the epineurium or adventitia was performed. The resection cavity was treated with cisplatin for three minutes, followed by irrigation with sterile water, iodine, and saline to minimize infection risk. The tumour boundary was marked with titanium clips for radiotherapy guidance. Haemostasis was ensured, and reconstruction of important muscles and ligaments was performed to preserve limb function. Negative-pressure drainage tubes were placed, and the incision was closed in layers. Routine pathological examination, including intraoperative frozen sections, when necessary, confirmed negative margins. In the MWA group, prophylactic internal fixation was performed for weightbearing bones, including the tibia and femur. Fixation primarily involved the use of long or anatomical plates, supplemented by bone cement filling as appropriate.

The Control group followed a similar resection procedure, but without ablation. A typical case is presented in the Supplementary Material.

Evaluation and follow-up

Clinical data were collected, including sex, age, tumour primary site, tumour size, pathological grade, pathological type, Enneking stage,²² imaging (radiograph, CT, MRI, etc), postoperative complications, and other treatments such as chemotherapy and radiotherapy. All patients underwent regular follow-up visits or consultations after surgery. In the first year, follow-up was every three months, every six months in the second and third years, and annually from the fifth year onwards. The follow-up mainly included a radiograph, contrast-enhanced CT, and MRI of the tumour. Postoperative local recurrence was defined as tumour recurrence confirmed by pathology of biopsy or imaging evidence. Overall survival (OS) was defined as the time from diagnosis to last follow-up or death. Postoperative progression-free survival (PFS) was the time from surgery to disease progression or death. Local disease-free survival (DFS) was the time for local tumour recurrence after surgery. Serious postoperative complications were recorded according to common terminology criteria for adverse events (CTCAE) 4.0,²³ including severe wound healing problems, deep infections, bone necrosis, wound burn, persistent pain, and major neurovascular injuries.

Statistical analysis

Statistical analyses were performed using SPSS v22.0 (IBM, USA) and R 4.4.2 (R Foundation for Statistical Computing, Austria). Categorical variables were presented as frequencies and percentages, while continuous variables were presented as means (SDs). For normally distributed variables, an independent-samples t-test was used; for non-normally distributed variables, non-parametric statistical analysis (Mann-Whitney U test) was applied. The chi-squared test or Fisher’s exact test was used to compare categorical variables, as approriate. Survival curves were plotted using the Kaplan-Meier method, and statistical significance was tested using the log-rank test. A p-value of < 0.05 was considered statistically significant.

Results

The sarcoma subtype distribution for both groups is shown in Table II. There were no statistically significant differences between the two groups in terms of sex, age, tumour size, site, and systemic treatments (radiotherapy and chemotherapy). The limbs were the most common primary location, with 12 cases (60%) in the Control group and 16 (66.7%) in the MWA group. The trunk was the next most common, with five cases (25%) in the Control group and five (20.8%) in the MWA group. The pelvis had three cases (15%) in the Control group and three (12.5%) in the MWA group. In terms of FNCLCC grade, the Control group had five cases of G2 and 15 cases of G3, while the MWA group had one case of G2 and 23 cases of G3, showing a significant difference (p = 0.045, Fisher’s exact test). Extended matching was performed for further analysis. Specifically, in the Control group, three patients received only radiotherapy, seven received both radiotherapy and chemotherapy, and ten received only chemotherapy; in the MWA group, two patients received only radiotherapy, six received both radiotherapy and chemotherapy, and 16 received only chemotherapy (p = 0.520, chi-squared test). The mean operating time was 230.83 minutes (SD 150.84) for the Control group compared with 270.00 minutes (SD 164.88) for the MWA group (p = 0.525, independent-samples t-test). Mean intraoperative blood loss was 504.55 ml (SD 868.7) for the Control group and 448.12 ml (SD 532.40) for the MWA group (p = 0.836, independent-samples t-test). The subgroup analysis based on tumour sites (limbs, trunk, and pelvis) and tumour size (10 cm, 7 cm, and 5 cm) showed no significant difference between the groups (Supplementary Material).

Table II.

Histological type of the two groups. All data are presented as n (%).

Subgroup type	Control group	MWA group
Fibrosarcoma	2 (10)	1 (4.2)
Undifferentiated sarcoma	1 (5)	3 (12.5)
Liposarcoma	2 (10)	1 (4.2)
Rhabdomyosarcoma	3 (15)	1 (4.2)
Synovial sarcoma	2 (10)	2 (8.3)
Ewing’s sarcoma	1 (5)	5 (20.8)
Alveolar soft part sarcoma	0	3 (12.5)
Angiosarcoma	1 (5)	0
Small round cell malignant tumour	2 (10)	2 (8.3)
Epitheloid sarcoma	2 (10)	0
MPNST	0	1 (4.2)
Unclassified sarcoma	4 (20)	5 (20.8)
Total no.	20	24

MPNST, malignant peripheral nerve sheath tumour; MWA, microwave ablation.

At the last follow-up, 12 patients in the Control group and eight patients in the MWA group experienced local recurrence. Ten patients in the Control group, and 14 patients in the MWA group, developed distant metastasis. No significant differences were observed in the median OS (MWA: 53.10 (SD 6.91), 95% CI 39.55 to 66.75) compared with Control (58.30 (SD 4.66), 95% CI 49.16 to 67.44; p = 0.512, log-rank test) and median PFS (MWA: 16.67 (SD 3.75), 95% CI 9.32 to 23.97) compared with Control (12.62 (SD 5.88), 95% CI 1.10 to 24.09; p = 0.691, log-rank test) between the two groups. The MWA group showed longer local DFS than the control group (33.91 months (SD 6.54), 95% CI 21.10 to 46.71 vs 48.02 months (SD 4.70), 95% CI 38.81 to 57.23; p = 0.047, log-rank test). The median local DFS in the control group was 17.54 (SD 6.38), 95% CI 5.03 to 30.05. The Kaplan-Meier curves comparing OS, PFS, and local DFS between groups are illustrated in Figure 4.

Fig. 4.

Kaplan-Meier curves comparing a) overall survival (OS), b) progression-free survival (PFS), and c) local disease-free survival (DFS) between groups.

Postoperative complications showed no significant difference (Table III, p = 0.143, Fisher’s exact test). The Control group showed three cases of poor wound healing, one of deep infection, one of deep vein thrombosis, and one of persistent pain. The MWA group reported four cases of poor wound healing and one case of deep infection and bone necrosis. Neither group reported any accidental nerve or vascular injuries. Two Control group and three MWA group patients required secondary surgery to deal with the wound.

Table III.

Comparison of complication rates between the two groups.

Complication	Control	MWA	p-value
Poor wound healing	3	4
Deep infection	1	2
Persistent pain	1	1
Deep vein thrombosis	1	0
Bone necrosis	0	1
Total no.	5	8	0.143

MWA, microwave ablation.

A subgroup analysis of complications was conducted. The rates of deep infections were 1/20 for the Control group and 2/24 for the MWA group (p > 0.05, Fisher’s exact test), while the return to theatre rates were 4/20 for the Control group and 6/24 for the MWA group (p = 0.734). Further logistic regression analysis revealed no significant association between postoperative debridement and the following factors: use of MWA (surgery alone vs combined with MWA, odds ratio (OR) = 1.25; 95% CI 0.26 to 6.47; p = 0.781), neoadjuvant chemotherapy (OR = 0.34; 95% CI 0.02 to 4.50; p = 0.404), tumour location (limb vs other, OR = 0.99; 95% CI 0.11 to 6.93; p = 0.991), or tumour size at thresholds of 10 mm (OR = 0.97; 95% CI 0.18 to 5.29; p = 0.970), 7 mm (OR = 0.60; 95% CI 0.11 to 3.30; p = 0.548), and 5 mm (OR = 6.65 × 10⁷; 95% CI not estimable; p = 0.993). The study included seven patients in the control and ten patients in the MWA group with bone invasion, respectively. Specifically, no statistically significant differences (p = 0.651, chi-squared test) were observed between the MWA and Control groups in either bone or soft-tissue treatments (Supplementary Material).

Notably, a severe complication involved a 13-year-old patient diagnosed with Ewing’s sarcoma of the left lower limb. Due to extensive tumour invasion, the patient underwent in situ inactivation ablation (100 W, intermittent for 30 minutes). Postoperatively, deep infection and severe poor wound healing occurred, with persistent tibial bone exposure. The patient was followed up for 52 months, and no recurrence was reported. However, 16 months post-operation, after receiving antibiotic therapy, multiple debridement procedures, suturing, and unsuccessful flap reconstructions, the decision to proceed with amputation was made following a multidisciplinary consultation.

Discussion

To the best of our knowledge, this represents the earliest report on clinical case-control cohort outcomes utilizing MWA for the inactivation of soft-tissue sarcomas. Our results indicate that intraoperative combined application of inactivation techniques can improve local control rates and prolong local progression-free survival, especially in high-risk STS with compartmental breakthrough.

The challenge of achieving satisfied limb function preservation and improving local tumour control remains a persistent concern for oncological surgeons, and the optimal treatment strategy is still unclear. Besides the histological grade (G1-3), the most widely recognized key risk factor is surgical margins.^3,4 The largest series of STS to date has demonstrated that tumour biology predominantly determines early outcomes, while the quality of surgical margins serves as a stronger predictor of late-stage mortality.^24-26 A landmark randomized controlled trial by the National Cancer Institute (NCI) introduced the concept of limb-sparing surgery for STS of the limbs, indicating that limb-sparing surgery with radiotherapy provided comparable OS and DFS to amputation (OS: 83% vs 88% (p = 0.99); DFS: 71% vs 78% (p = 0.75)).¹⁰ In our study, we attempted to use microwave-mediated thermal ablation intraoperatively to inactivate the tumour and its margins, similar to the concept of localized radiotherapy. Previously, intraoperative MWA was effective in the treatment of giant cell tumours, leading to reduced recurrence rates and improved local tumour control.²⁷ In cases of sarcomas, percutaneous MWA has been applied to treat pulmonary metastases of sarcomas, achieving effective local tumour control, with one-year and two-year rates of 97% and 95% for tumours ≤ 1 cm, and 74% and 62% for tumours > 1 cm.²⁸ In 2015 and 2017, Li et al^16,17 reported a prior work, using MWA intraoperatively as a strategy to reduce recurrence in osteosarcoma patients, achieving favourable five-year local tumour control (91%, 115 to 133 months). and five-year survival rates (82% 104 to 128 months). In 2022, Zheng et al¹⁸ reported 15 clinical cases of bone tumours, and one case of STS with a history of recurrence, treated with surgery combined with local MWA. Encouragingly, our study reported a significant improvement in local DFS, aligning with our goal of reducing the rate of microscopic margin positivity. Despite the relatively higher proportion of G3 tumours in the MWA group, showing lower local DFS, is a noteworthy observation. This may indirectly reflect the potential local control benefit provided by intraoperative MWA, even in cases of more aggressive tumour behaviour. From a macro perspective, MWA is mainly a thermal effect, which is a physical factor. Its ability to improve local tumour control is due to its ability to utilize its thermal energy to inactivate local lesions.^16,17 We speculate that inactivation may eliminate small satellite metastatic foci around the tumour periphery, thereby achieving a safe surgical margin (a conceptual diagram is provided in the Supplementary Material). In fact, due to the limitations of the surgeon’s sampling range and pathological microscopic techniques, the accuracy of considering a negative intraoperative frozen pathology result as a safe surgical margin remains controversial.^29-32 Therefore, MWA was applied in addition to standard tumour resection to further inactivate potential residual microscopic foci, which was also the primary objective of this study. However, as of the last final follow-up, no significant difference in OS was observed, likely due to the limited sample size caused by the tumour aggressiveness, intergroup heterogeneity, and the low incidence of this disease.

The aim of ablation was to inactivate residual tumour cells at the periphery and facilitate subsequent resection by creating a more clearly defined and safer surgical plane. This strategy involved performing in situ MWA prior to tumour resection, targeting both the tumour mass and surrounding reactive or suspicious regions, such as tumour tails, oedematous tissue, or adjacent bone potentially harbouring microscopic infiltration. Several advantages of pre-resection ablation were observed. Firstly, it may reduce the risk of tumour dissemination, particularly in cases where en-bloc resection is technically challenging. Secondly, the haemostatic effect of MWA helps to minimize intraoperative bleeding and improves surgical visibility. Thirdly, it enables simultaneous removal of necrotic and tumour tissue, thereby avoiding residual devitalized tissues—such as necrotic tissue—that may result from post-ablation. These remnants can increase postoperative inflammation and delay wound healing.

Complications after STS resection are common, with poor wound healing being a key concern, often linked to wide excision of superficial skin, and prior chemo- or radiotherapy.^8,33-35 The complication rate indicated no significant difference between groups. However, thermal ablation techniques themselves may lead to heat-related damage. Thus, proper tissue protection is crucial to avoid heat injury-related issues during thermal ablation. In our study, patients experienced related MWA transient pain or burning sensations, which resolved postoperatively. This may be attributed to visualized ablation during surgery, saline gauze wrapping, and cold saline irrigation. Both groups included patients with bone invasion. No statistically significant differences in complications were observed (Supplementary Material). Tumour extension beyond anatomical compartments—including invasion into bone—is often a biological signal of aggressive behaviour. MWA offers several advantages in bone tissue: it is less affected by tissue impedance, achieves higher and faster intratumoral temperatures, and allows deeper and more uniform thermal penetration, even in dense cortical bone. This technique could provide a meaningful benefit for this challenging patient subgroup. Reportedly, high temperatures may increase bone fragility. In the MWA group, prophylactic internal fixation was performed for weightbearing bones, including the tibia and femur (four cases). Fixation primarily involved the use of long or anatomical plates, supplemented by bone cement filling as appropriate. As of the last follow-up, no fractures had been reported. Biomechanically, it appears to maintain satisfactory stability, as MWA does not involve the removal of the primary load-bearing cortical bone.

Notably, this study cohort reported a severe complication. A 13-year-old patient with Ewing’s sarcoma, involving extensive invasion of the tibial cortex and deep tissues, underwent deep layer-by-layer ablation with high-power, prolonged MWA. Although complete tumour inactivation was achieved, this caused severe ischaemic necrosis, compounded by the tibia’s limited muscle attachments, poor skin vascularization, and prior history of chemotherapy and radiotherapy. These factors contributed to wound healing difficulties, leading to refractory infection and finally amputation. Similarly, Li et al¹⁷ reported that 31% of patients undergoing limb salvage surgery with adjuvant ablation developed epiphyseal necrosis, and one needed amputation due to deep infection. This case highlights the need for caution when using this technology in patients with multiple high-risk infection factors, particularly at the tibial site. Prompt consultation with a skilled wound care team is important.

This study has several limitations. Firstly, it is a retrospective, single-centre study with a small sample size, which introduces potential bias and limits the generalizability of the findings. Secondly, we acknowledge that the use of MWA for tumours was influenced by factors such as anatomical location, nearby critical neurovascular structures, tumour size, and invasion sites, which made standardizing treatment parameters (e.g. power, duration, and extent) challenging and also introduced selection bias. These factors, often based on the clinical team’s experience, limit the uniform application of the technique. Finally, the rarity of STS and the complex classification of subtypes further restrict the expansion of the sample size and may affect the representativeness of the study results. Currently, no studies have definitively identified which subtypes of sarcomas have potential responsiveness to ablation inactivation.

In conclusion, the combined in situ ablation inactivation during limb-sparing surgery for high-risk STS can enhance local tumour control and prolong local DFS, offering an alternative approach without increasing complications.

Take home message

- This study investigates the effectiveness and safety of incorporating microwave ablation during limb-sparing surgery for high-risk soft-tissue sarcoma.

- Our results demonstrated improved local tumour control and prolonged disease-free survival with no significant increase in complications.

Data Availability

The datasets generated and analyzed in the current study are not publicly available due to data protection regulations. Access to data is limited to the researchers who have obtained permission for data processing. Further inquiries can be made to the corresponding author.