Abstract
Purpose
The main predictors in the literature of local control for patients operated on for a soft tissue sarcoma are age, local presentation status, depth, grade, size, surgical margins and radiation. However, due to the competing effect of death (patients who die are withdrawn from the risk of local recurrence), the influence of these predictors on the cumulative probabilities may have been misinterpreted so far. The objective of the study was to interpret the influence of known predictors of local recurrence in a competing risks setting.
Method
This single center study included 1519 patients operated on for a localized soft tissue sarcoma of the extremity or trunk. Cox models were used to estimate the cause specific hazard of known predictors on local recurrence. Cumulative incidences were estimated in a competing risks scenario.
Results
Overall the cumulative probabilities of local recurrence at 2, 5, and 10 years were 5.4% (4.3%–6.7%), 8.2% (6.8%–9.8%), and 11.7% (9.8%–14.3%). The cumulative probabilities of metastasis at 2, 5, and 10 years were 23.3% (21.1%–25.5%), 28.7% (26.2%–31.1%), and 33.7% (30.8%–36.7%). Older age, locally recurrent, high grade and deep tumors, absence of radiation and positive surgical margins were significantly associated with an increased risk of local recurrence. However, when considering competing risks, the cumulative probabilities of local recurrence were significantly different only with presentation status (P < 0.0001), surgical margins (P < 0.0001) and use of adjuvant radiation (P = 0.04). At 10 years, the cumulative probability of local recurrence was 10.6% and 22.6% for patients presenting with a primary or locally recurrent tumor, 9.3% and 23.3% for patients with negative or positive surgical margins, and 9.8% and 16.8% for patients receiving or not receiving radiation respectively. There was no difference in the cumulative probabilities of local recurrence with regard to tumor depth (P = 0.29), size (P = 0.78) or grade (P = 0.29). Patient survival at 2, 5, and 10 years was 85.5% (95% CI: 83.7%–87.4%), 74.6% (95% CI: 72.1%–77.1%), and 64.3% (95% CI: 61%–67.7%).
Conclusion
The effect of variables on the cumulative probability of local recurrence should be interpreted in a competing risks setting. Grade and depth are not associated with an increased cumulative probability of local recurrence.
