638 - Outcome following unplanned excision in soft tissue sarcoma. Results of a multicentre study including 728 patients.

Background

Misdiagnosis of soft tissue sarcoma (STS) is common, due to their rarity and unclear clinical presentation. As a result, unplanned excisions (UE) may occur, most often necessitating further treatment at specialised tumour centres. Therapy includes re-resection and adjuvant radiotherapy (ARTX), being associated with increased morbidity. Results on UE’s impact on overall survival (OS) are contradictory, though.

Methods

728 STS patients (376 male, 352 female; mean age: 58 years) undergoing primary surgery or re-resection following UE at three tumour centres were retrospectively included. Median follow-up was 5.5 years. Differences between UE- and non-UE-patients were analysed using chi-square and t-tests. Log-rank and Gray’s tests were applied for time-to-event analyses. Based on differences between UE- and non-UE-patients at baseline, a propensity score of being in the UE-group was estimated. Based on the propensity score, an inverse-probability-of-UE-weight (IPUEW) was calculated. This allowed re-calculation of time-to-event analyses following adjustment for imbalances between non-UE- and UE-patients.

Results

UE had been performed in 281 patients (38.6%), with similar incidences at the three tumour centres. Small (p < 0.005) and superficially located STS (p < 0.005) with a long history of symptoms (p < 0.005), male gender (p = 0.05) and young age (p = 0.036) raised the risk of an UE being performed. At re-resection, plastic reconstruction (p < 0.005) and ARTX (p = 0.041) were significantly more common in UE-patients. In the univariate analysis, UE-patients had a significantly better OS (5-/10-year OS: 78.6%/63.3% for UE; 70.6%/57.9% for non-UE; p = 0.028). Due to a strong correlation between positive prognostic factors and a prior UE, survival analyses were re-calculated after weighting for the IPUEW. As a result, the prognostic benefit of UE in terms of OS was lost (p = 0.241).

Conclusions

Morbidity is raised in patients following UE due to increased necessity of plastic reconstruction and ARTX. However, there is no direct impact of UE on OS. Nevertheless, it is arguable whether a more aggressive approach in the UE-group compensates for the inappropriate primary resection. Thus, UE must be avoided by all means.

Clinical trial identification

Legal entity responsible for the study

Medical University of Graz.

Funding

Has not received any funding.

Editorial Acknowledgement

Disclosure

All authors have declared no conflicts of interest.