Synovial sarcoma disease characteristics and primary tumor sites differ between patient age groups: a report of the Cooperative Weichteilsarkom Studiengruppe (CWS)

BACKGROUND: Older age is associated with worse outcome in synovial sarcoma (SS) patients. Differences in disease presentation among distinct age groups, however, are currently unknown.

METHODS: SS patients < 21 years registered in consecutive CWS trials over the period of 1981-2018 were evaluated. Characteristics were analyzed according to age groups using the Fisher's exact test.

RESULTS: The study population included 432 SS patients. Disease characteristics differed according to age groups of children (0-12 years, n = 176), adolescents (13-16 years, n = 178), and young adults (17-21 years, n = 78). The proportion of invasive tumors (T2) was significantly higher in older patients: children 33%, adolescents 39% and young adults 54%, p = 0.009805. Similarly, the proportion of tumors > 10 cm was higher (13%, 21%, 31%; p = 0.005657) whereas conversely, the proportion of small tumors < 3 cm was lower in older patients (29%, 24%, 6%; p = 0.000104). The presence of metastases at first diagnosis was also highest in older patients (6%, 10%, 21%, p = 0.000963). Notably, the proportion of thigh tumors was higher in older patients (p = 0.04173), whereas the proportion of head-neck tumors was lower in older patients (p = 0.08896).

CONCLUSIONS: The rates of large, invasive tumors and the presence of metastases are significantly associated with older patient age. Localization to the thigh is more frequent in older patients.

DISCUSSION: The causes for these variations require further exploration.