Impact of Surgical Margins in Chest Wall Chondrosarcomas: A CanSaRCC Study

ABSTRACT

Background

Chest wall chondrosarcoma is the most common primary malignant bone tumor of the thoracic cage. Owing to its resistance to chemotherapy and radiotherapy, complete surgical excision with negative margins remains the cornerstone of treatment. However, the optimal margin width for local control and survival remains uncertain.

Methods

Data from nine Canadian sarcoma centres participating in the CanSaRCC registry were retrospectively reviewed. Patients aged ≥ 18 years with pathologically confirmed primary chest wall chondrosarcoma (2000–2024) who underwent curative‐intent resection were included. Margins were defined as the minimum measured distance from tumor to resection margin, irrespective of tissue type and categorized as positive, < 4 mm, or ≥ 4 mm. Overall survival (OS), disease‐free survival (DFS), and local recurrence free survival (LRFS) were analysed using Kaplan–Meier and multivariable Cox regression.

Results

Among 147 patients (median age 54 years (range; 21–85), 16% had positive margins, 52% < 4 mm, and 24% ≥ 4 mm. At 5 years, OS and DFS were 77% (±4.8%) and 68% (±5.2%), respectively, for the entire cohort. Independent predictors of worse overall survival included tumor size ≥ 10 cm (HR 3.23, p = 0.021) and grade 3 tumors (HR 12.40, p < 0.001) but not margin size (margin ≥ 4 mm; HR 0.70, p = 0.512). Margins ≥ 4 mm significantly reduced local recurrence (HR 0.12, p = 0.023).

Conclusions

In primary chest wall chondrosarcoma, tumor biology rather than surgical margin width drives systemic outcomes. Margins ≥ 4 mm improve local control, supporting balanced resections that preserve function while maintaining oncologic safety.

1. Introduction

Primary tumors of the chest wall comprise a heterogeneous group of neoplasms originating from bone and soft tissue, with sarcomas—predominantly chondrosarcoma, Ewing sarcoma, and Askin's tumors—accounting for the majority of malignant cases [1]. Among these, chondrosarcoma is the most frequent malignant bone tumor in adults, encompassing ~15%–20% of all chest wall sarcomas [2, 3, 4]. These tumors most often originate from the ribs (~80%) and less commonly from the sternum (~20%). Overall, chondrosarcoma is the leading primary bone sarcoma in adults with ~15% occur in the thoracic cage, with an annual incidence of less than 0.5 per million [4, 5].

Chondrosarcomas are inherently resistant to chemotherapy and radiotherapy. Contributing factors include a low proliferation rate, dense extracellular matrix, limited vascularity, and expression of multidrug resistance pathways such as MDR1/P‐glycoprotein [3, 5]. Consequently, complete surgical excision with wide, tumor‐free margins remains the only curative approach, supported by multiple institutional studies [1, 3, 4, 5, 6, 7]. Surgical margin status is thought to be an important prognostic factor for local recurrence as well as overall survival in chest wall chondrosarcoma [2, 8]. King et al. (1986) proposed a 4 cm margin for chest wall chondrosarcoma based on improved survival outcomes; however, these findings were obtained from a single centre, retrospective cohort and have not been universally validated [8].

In chondrosarcomas of the extremities and pelvis, narrower margins are accepted when dictated by anatomic constraints, without clear detriment to local control or overall survival [9]. Similarly, for low‐grade extremity tumors, there has been a shift toward intralesional curettage, reflecting a broader move toward less invasive approaches in the setting of favorable tumor biology [10]. Extensive chest wall resections can lead to substantial morbidity, including major bony and soft tissue defects, complex reconstructive requirements, impaired respiratory mechanics, and cosmetic deformity. These challenges underscore the need for careful surgical planning to achieve oncologic clearance while preserving function [11, 12].

Despite multiple retrospective and institutional reports, no large‐scale collaborative study has specifically evaluated the relationship between margin width, survival, and local recurrence in primary chest wall chondrosarcoma. Existing recommendations rely primarily on older, heterogeneous datasets or extrapolation from other anatomic sites. Modern registries, such as the Canadian Sarcoma Research and Clinical Collaboration (CanSaRCC), present an opportunity to address this gap.

2. Methods

Ethics approval for this study was granted by the Research Ethics Boards of all participating institutions under the CanSaRCC Consortium agreement. Following approval, patient data from nine centers—Princess Margaret Cancer Centre (Toronto), Mount Sinai Hospital (Toronto), the McGill University Health Centre (Montreal), BC Cancer (British Columbia), Hôpital Maisonneuve Rosemont (Montreal), Université Laval (Quebec City), Alberta Health Services (Calgary), Ottawa Hospital Research Institute (Ottawa), and Nova Scotia Health—were compiled into the CanSaRCC database. Patients aged 18 years or older were eligible for inclusion if they had pathologically confirmed primary chest wall chondrosarcoma between 2000 and 2024, with the primary tumor located in the chest wall, thoracic paraspinal region, rib, or sternum, and documented curative surgical resection of the primary tumor. All patients had measurable disease at the initiation of surgical intervention. Resection margins and histological subtypes were reported if dictated by the pathologist in biopsy or surgical pathology reports. Chondrosarcomas were graded according to the World Health Organization (WHO) classification using a conventional three‐tier histologic grading system (Grade 1–3). A total of 147 patients met these criteria and were included in the study.

Information on patient demographics, disease features, and treatment details was collected using a standardized case report form and summarized through descriptive statistics. Surgical details were further reviewed for postoperative complications, including wound infection, hematoma, mesh infection, respiratory failure, or perioperative death. Information was additionally gathered regarding patients' need for postoperative ICU admission and the specific type of plastic or surgical reconstruction undertaken during the curative procedure. Data on demographics, tumor characteristics, surgical variables, and post‐resection outcomes, including overall survival (OS) and disease‐free survival (DFS), were retrospectively extracted from the CanSaRCC database.

Surgical margins were categorized as intralesional (macroscopically or microscopically positive, 0 mm), < 4 mm, or ≥ 4 mm. For this review, the narrowest margin was defined as the minimum measured distance from tumor to resection margin, irrespective of tissue type. These values were based on previous literature evaluating margin status in flat bone chondrosarcomas [6].

2.1. Statistical Analysis

Overall survival (OS), DFS and local recurrence free survival (LRFS) were estimated using Kaplan–Meier survival curves. Multivariable Cox proportional hazards regression analyses were conducted to identify independent predictors of OS, DFS, and local recurrence. DFS was defined as the interval from the date of curative chest wall chondrosarcoma resection to the earliest occurrence of local recurrence, disease progression, or disease‐specific death; patients without an event were censored at last follow‐up. OS was defined as the interval from the date of surgery to death from any cause, with surviving patients censored at last follow‐up. Local recurrence free survival was defined as the interval from the date of surgery to the first histologically or radiographically confirmed recurrence within the operative field. Patients without local recurrence were censored at last follow‐up or at the date of distant metastasis or death if these occurred before local recurrence. Variables demonstrating clinical relevance or statistical significance on univariable analysis were entered into the multivariable Cox regression models to adjust for potential confounders.

3. Results

3.1. Cohort Demographics

The cohort included 147 patients with a median age of 54 (range 21–85) of whom 65% were male (Table 1). Most tumors were intermediate or high grade, with 47% grade 2% and 9% grade 3, while 40% were low grade. Tumor size was most commonly between 5 and 10 cm (46%), with 16% exceeding 10 cm. Histologic subtype was frequently unspecified (67%); among classified cases, conventional (14%) and well‐differentiated (8%) chondrosarcoma were most common. Patients had undergone prior surgery to the tumor in 28% of cases. When evaluated by margin status, 52% of patients with positive margins had undergone prior surgery, compared to 22% and 23% of patients with < 4 mm and ≥ 4 mm margins, respectively. No other demographic differences were found between margin status groups on univariate analysis.

Table 1.

Cohort demographics.

Variable	Total Cohort (n = 147)	Positive (n = 21)	< 4 mm (n = 77)	≥ 4 mm (n = 35)	p
Age at diagnosis (median, range)	54 (21–85)	52 (21–81)	57 (23–83)	51 (21–85)	0.751
Sex (F:M)	51:96	9:12	29:48	10:25	0.507
Grade
1  2  3  Unknown	59 69 13 6	9 9 2 1	29 38 8 2	16 15 3 1	0.984
Size
< 5 cm  5–10 cm  > 10 cm	52 67 24	5 11 4	32 36 9	9 17 8	0.251
Histologic Subtype					0.274
Conventional  Well Differentiated  Dedifferentiated  Myxoid  Clear Cell  Periosteal  Not specified	20 12 7 6 2 1 99	1 4 0 0 0 0 16	13 5 5 4 1 1 48	2 1 1 2 0 0 29
Previous Surgery	41	11	17	8	0.017
Soft Tissue Reconstruction
None  Free flap  Pedicled flap  Local/rotational flap  Skin graft  Not recorded	75 16 4 23 6 23	10 1 2 2 2 4	41 8 0 15 3 10	18 7 2 2 1 5	0.054
Mesh Reconstruction
Yes  No  Not recorded	69 19 59	11 4 6	54 14 9	26 3 6	0.140
Postoperative Complication
Respiratory  Infection  Flap failure  Other  NR/None	6 6 2 1 128	0 0 0 0 21	3 3 1 1 69	3 3 1 0 28	0.630
Local Recurrence	19	4	11	2	0.292

Note: Statistically significant values p < 0.05 are in bold.

3.2. Surgical Outcomes

Of those with margin status available (n = 133), closest surgical margins were positive in 21 patients (16%), < 4 mm in 77 (52%), and ≥ 4 mm in 35 (24%). Soft tissue reconstruction was performed in 35 patients (26%), most commonly with local/rotational flaps (17%) or free flaps (12%), while 75 patients (56%) did not require reconstruction. Mesh reconstruction was used in 69 patients (52%). Postoperative complications occurred in 15 patients (11%), including respiratory complications (4%) and infections (4%). Local recurrence developed in 19 patients (14%). Local recurrences developed in 19% of patients with positive margins, 14% of patients with margins < 4 mm and 6% of patients with ≥ 4 mm margins. No differences in surgical outcomes were found between margin status groups on univariate analysis. With respect to local recurrence rates in the setting of positive surgical margins, local recurrences occurred in 22% of patients with grade 1 tumors, 11% of patients with grade 2 tumors and 50% of patients with grade 3 tumors.

3.3. Survival

At 2 years, overall survival and disease‐free survival were 90% (95% CI; ±3.2%) and 81% (±4.1%), respectively, and at 5 years, 77% (±4.8%) and 68% (±5.2%), respectively.

Overall survival did not significantly differ based on surgical margin status (p = 0.273). At 2‐year follow‐up, overall survival was 88% (±11.1%), 93% (±5.9%), and 94% (±12%) for patients with positive margins, < 4 mm margins and > 4 mm margins, respectively. Overall, 5‐year survival was 76% (±21%), 73% (±12%) and 81% (±12%) for patients with positive margins, < 4 mm margins and > 4 mm margins, respectively (Figure 1).

Figure 1.

Overall survival stratified by closest surgical margins.

Disease free survival did not significantly differ based on surgical margin status (p = 0.681). At 2‐year follow‐up, DFS was 77% (95% CI; ±14), 81% (±6%), and 80% (±11%) for patients with positive margins, < 4 mm margins and ≥ 4 mm margins, respectively. Disease free 5‐year survival was 58% (±23%), 68% (±13%), and 72% (±14%) for patients with positive margins, < 4 mm margins and ≥ 4 mm margins, respectively (Figure 2).

Figure 2.

Disease free survival stratified by closest surgical margins.

Local recurrence free survival did not significantly differ based on surgical margin status (p = 0.087). At 2 years, LRFS was 87% (±17%), 89% (±8%), and 97% (±6%) for patients with positive margins, < 4 mm margins and ≥ 4 mm margins, respectively. Local recurrence free survival at 5 years was 70% (±25%), 83% (±10%), and 93% (±9%) for patients with positive margins, < 4 mm margins and ≥ 4 mm margins, respectively (Figure 3).

Figure 3.

Local recurrence free survival stratified by closest surgical margins.

3.4. Regression Analysis

On multivariable Cox regression analysis, older age (HR 1.40, 95% CI 1.12–1.67, p = 0.004), tumor size ≥ 10 cm (HR 3.23, 95% CI 1.19–8.77, p = 0.021), and higher histologic grade (HR 12.40, 95% CI 3.78–40.45, p < 0.001) were independently associated with worse overall survival (Table 2). Surgical margin status was not significantly associated with overall survival.

Table 2.

Cox regression analysis evaluating predictors of overall survival.

Variable	Hazard Ratio	95% CI		p
		Lower	Upper
Age (per decade)	1.40	1.12	1.67	0.004
Closest Surgical Margin
Positive	Ref
< 4 mm	1.096	0.42	2.88	0.853
≥ 4 mm	0.70	0.24	2.02	0.512
Histologic Grade
1	ref
2	2.29	0.98	5.38	0.056
3	12.40	3.78	40.45	< 0.001
Tumour Size
< 5 cm	ref
5–10 cm	1.30	0.52	3.21	0.573
≥ 10 cm	3.23	1.19	8.77	0.021

Note: Statistically significant values p < 0.05 are in bold.

Similarly, when evaluating disease free survival, tumor size ≥ 10 cm (HR 6.57, 95% CI 2.45–17.61, p < 0.001), and grade 2 (HR 3.37, 95% CI 1.55–7.34, p = 0.001) and grade 3 (HR 8.63, 95% CI 3.07–24.23, p < 0.001) tumors were independently associated with worse overall survival (Table 3). Surgical margin status was not significantly associated with DFS.

Table 3.

Cox regression analysis evaluating predictors of disease‐free survival.

Variable	Hazard Ratio	95% CI		p
		Lower	Upper
Age (per decade)	1.23	1.00	1.46	0.052
Closest Surgical Margin
Positive (ref)
< 4 mm	0.69	0.30	1.61	0.395
≥ 4 mm	0.625	0.25	1.55	0.310
Histologic Grade
1(ref)
2	3.37	1.55	7.34	0.002
3	8.63	3.07	24.23	< 0.001
Tumour Size
< 5 cm (ref)
5–10 cm	2.05	0.86	4.89	0.105
≥ 10 cm	6.57	2.45	17.61	< 0.001

Note: Statistically significant values p < 0.05 are in bold.

On multivariable cox regression analysis of local recurrence, surgical margins ≥ 4 mm were associated with a decreased risk of local recurrence (HR 0.12, 95% CI 0.02–0.74, p = 0.023). Tumor size of 5–10 cm and grade 3 tumors were also predictive of local recurrence (Table 4).

Table 4.

Cox regression analysis evaluating predictors of local recurrence.

Variable	Hazard Ratio	95% CI		p
		Lower	Upper
Closest Surgical Margin
Positive (ref)
< 4 mm	0.51	0.15	1.72	0.27
≥ 4 mm	0.12	0.02	0.74	0.023
Histologic Grade
1 (ref)
2	2.46	0.63	9.64	0.197
3	47.8	8.43	270.75	< 0.001
Tumour Size
< 5 cm
5–10 cm	31.7	3.12	321.10	0.003
≥ 10 cm	11.1	0.89	139.51	0.062

Note: Statistically significant values p < 0.05 are in bold.

4. Discussion

This multi‐institutional Canadian study provides a comprehensive analysis of prognostic factors in primary chest wall chondrosarcoma. While margin status has historically been considered the most important determinant of outcomes, our findings challenge this paradigm. In our cohort, margin width was not independently associated with OS or DFS. Patient age, tumor size, and histologic grade were found to be predictors of systemic outcomes. These results suggest that tumor biology, rather than the extent of surgical resection, primarily determines long‐term survival.

Previous studies have highlighted the importance of negative surgical margins. King et al. reported that wide resections achieving margins of at least 4 cm improved both survival and local control in chest wall chondrosarcoma [8]. The Scandinavian Sarcoma Group, in a 106‐patient series, similarly identified margin status as an important predictor of local recurrence, while also emphasizing the prognostic impact of histologic grade [4]. Alvarado et al., in a National Cancer Database evaluation of chest wall sarcomas, demonstrated that positive margins were associated with worse overall survival. However, their analysis did not include histologic grade as a potential confounding variable, limiting the interpretability of the results. A contributing difference between our findings and prior studies may be that all patients in our cohort were treated at high‐volume, tertiary sarcoma referral centers, where multidisciplinary expertise and specialized surgical care optimizes both oncologic and functional outcomes [2, 13].

Our study adds important nuance to the existing literature. While margin status was not independently associated with OS or DFS, surgical margins had a significant, independent impact on local control. Surgical margins ≥ 4 mm were an independent predictor of lower local recurrence rates compared to positive margins. This observation is consistent with reports from the pelvic chondrosarcoma literature, where ≥ 4 mm negative margins have been associated with acceptable local control without a detriment to survival [6, 9, 14]. Stevenson et al. (2018) demonstrated that margins of at least 4 mm significantly reduced local recurrence rates in pelvic chondrosarcoma patients [6]. Taken together, these findings suggest that relatively narrow but clear margins may be adequate in chest wall chondrosarcomas. Given that radical resections can necessitate complex reconstruction, impair respiratory mechanics, and cause cosmetic deformity, these results support the importance of carefully balancing oncologic clearance with surgical morbidity [15]. In our series, over one‐quarter of patients required soft tissue reconstruction, and more than half required mesh reconstruction, highlighting the potential impact of more extensive resections.

It is important to note that the pleural margin was not consistently reported among included patients. Owing to the anatomic characteristics of the pleural surface, this boundary is not universally regarded as a true surgical margin—similar to how the distance to skin is not considered a margin when the skin is included in the resection. In the context of chest wall sarcoma, the margins of primary oncologic significance are the radial margins, which more accurately reflect the completeness of tumor excision and are most relevant to assessing local control. A limitation of the current study is that the exact anatomic location of local recurrences was not consistently defined or recorded, precluding analysis of recurrence patterns (e.g., pleural vs. radial margins). As a result, we are unable to further delineate the relative importance of specific margin types.

The prognostic significance of age, tumor size, and histologic grade observed in our study is consistent with prior data [14, 16, 17]. Larger tumors (≥ 10 cm) and higher‐grade histologies were strongly associated with inferior OS and DFS, findings that echo results from extremity and pelvic chondrosarcoma cohorts, where tumor biology often outweighs the effect of local surgical factors [16, 17]. Similarly, older age has been variably reported as a predictor of survival in chest wall sarcoma, and our data reinforce its independent role in prognosis [16, 18, 19]. Together, these results emphasize that systemic outcomes are largely dictated by tumor biology, underscoring the importance of accurate histopathologic assessment and risk stratification.

The strengths of this study include its multi‐institutional design, standardized data collection across nine sarcoma centers, and relatively large sample size compared with prior series of chest wall chondrosarcoma. Limitations include the retrospective nature of the analysis, incomplete recording of histologic subtype in a substantial proportion of patients, and potential variability in the measurement and reporting of margin width across institutions. Additionally, while the CanSaRCC registry provided robust national coverage, the rarity of this disease limited the power for subgroup analyses, particularly regarding histologic variants and reconstructive strategies.

5. Conclusion

In this multi‐institutional analysis of primary chest wall chondrosarcoma, patient age, tumor size, and histologic grade were independent predictors of overall and disease‐free survival. Surgical margin status was not associated with systemic outcomes, but margins ≥ 4 mm were protective against local recurrence. These findings suggest that while adequate surgical clearance remains critical for local control, long‐term survival is primarily driven by tumor biology. Surgical strategies should therefore balance oncologic safety with the morbidity of extensive resections.

Conflicts of Interest

The authors declare no conflicts of interest.

Synopsis

In a Canadian multi‐institutional study of primary chest wall chondrosarcoma, surgical margin width was not independently associated with overall or disease‐free survival. Margins ≥ 4 mm were associated with improved local control, providing context for surgical decision‐making.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.