Older patients appeared to receive greater benefit from adjuvant radiotherapy (RT) for soft tissue sarcoma (STS) than younger patients, according an analysis of the Surveillance, Epidemiology, and End Results (SEER) database.
Several STS subtypes were associated with significant RT benefits to overall survival (OS) and disease-specific survival (DSS) in patients older than 65 years, but survival differences were not significant in younger patients. These seven subtypes included leiomyosarcoma (hazard ratio, 0.84; P = .04), sarcoma not otherwise specified (HR, 0.66; P less than or equal to .001), liposarcoma not otherwise specified (HR, 0.72; P = .05), myxoid liposarcoma (HR, 0.50; P = .02), rhabdomyosarcoma (HR, 0.23; P less than or equal to .001), epithelioid (HR, 0.01; P less than .01) and myxoid chondrosarcoma (HR, 0.02; P = .04). One STS subtype, synovial sarcoma, was associated with significant RT benefit only in younger patients (HR, 0.73; P = .04). Malignant fibrous histiocytoma was the only subtype to show significant benefit in the overall cohort as well as both age groups.
“We observed a statistically significant improvement in OS and DSS in all patients receiving RT compared to surgery alone across the majority of histological subgroups. More importantly, there was no significant improvement in younger patients compared to a significant improvement in older patients, suggesting that survival benefits in response to RT are significantly affected by age-related differences,” wrote Dr. Noah K. Yuen of the Department of Surgery, University of California, Davis, and his colleagues (Anticancer Res. 2016 Apr;36(4):1745-50). The findings suggest that older patients may benefit more than previously appreciated, and while implementation of RT among the elderly may present challenges, according to the investigators, “our data suggest that this approach deserves greater attention.”
Previous population-based retrospective studies have demonstrated a similar benefit with surgery and adjuvant RT; however, randomized clinical trials have shown significant improvement in local control but have failed to show significant improvement in OS. The authors acknowledged the potential impact of unmeasured confounding factors on the retrospective study. Selection bias may be present if healthier older patients preferentially received RT; a subpopulation of healthier individuals would be expected to have better survival.
The SEER database analysis included 15,380 patients with non-metastatic STS who underwent surgery during 1990 to 2011. The mean age of the cohort was 56.6 years and one-third were age 65 years or more. As the most common histologic subtype, leiomyosarcoma accounted for 30.1% of all tumors. Most of the patients treated with RT (68.3%) had high-grade tumors.