(P 310) PROGNOSTICATION AND EPIDEMIOLOGY OF CLEAR CELL SARCOMA: A SEER STAT RETROSPECTIVE ANALYSIS

Objective: Clear cell sarcoma (CCS), formerly known as malignant melanoma of soft parts, is an exceedingly rare and a highly aggressive subtype of soft tissue sarcomas. Originating from mesenchymal tissue, CCS accounts for < 1% of all the sarcomas and are frequently seen in young adults. Prior radiation exposure or rare inherited cancer syndromes (i.e., Li-Fraumeni syndrome/Retinoblastoma) are among common predisposing factors. It presents as a painless, firm nodule that can evolve into a non-healing ulcer with occasional pulmonary metastasis. Treatment modalities include surgical resection for localized disease and systemic chemotherapy for metastatic disease. Understanding prognosticators can aid in determining outcomes and developing strategies to curb morbidity and mortality from this rare neoplasm.

Methods: Clear cell sarcoma (excluding kidney) cases diagnosed after the age of 20 years were retrospectively identified and extracted, using the ICD Code 9044/3, from Surveillance, Epidemiology and End Result database Research Plus Data, 17 Registries, Nov 2023 Sub (2000-2021). The analysis was stratified based on age, sex, race, laterality, primary site labelled, stage, median household income inflation adjusted to 2022, and treatment modalities used. Survival curves were compared using Log-Rank test (GraphPad Prism).

Results: Total 299 cases of clear cell sarcoma were found from 2000 to 2021. Of the reported cases, ~54.18% were males and ~45.82% were females. The neoplasm was most commonly seen in White (~55.52%) patients followed by Hispanic (~19.73%), Black (~15.72%), Asians/Pacific Islander (~7.02%), and Alaskans/Native American (~1.34%) patients. The average age of diagnosis was 45.6 years. The median of survival (MoS) for males was 31 months and females was 84 months (CI:0.2693-0.5058, HR: 1.465, p 0.0161). MoS calculated for race was significant for: White (62), followed by Native Americans/Alaskans (49), Asian/PI (46), Hispanics (35), and Black (22). Analysis with respect to stage showed better outcomes at earlier stages (localized or regional) (p < 0.0001). Survival curves on the basis of age and inflation adjusted-median household income showed no statistical difference. Median of survival based on primary site was significant for skin and soft tissue (48), breast (undefined - most likely from no observed death in the category), GI (9), bones (7), lung (4), nervous system (2.5) and peritoneum and retroperitoneum (9). MoS calculated for treatment type was compared for: surgery 62 vs no-surgery 7 (p value < 0.0001) and chemotherapy 12 vs no chemotherapy 76 (p value < 0.0001); whereas, data for radiotherapy was statistically insignificant. MoS analysis for laterality revealed higher survival with unilateral involvement (p 0.0001).

Conclusion: Clear cell sarcoma is an ultra-rare malignancy with only 299 cases reported between 2000-2021. This aggressive sarcoma favors Caucasians with a slight male predilection. Overall superior survival was observed with Caucasians, female gender, earlier stage, unilateral disease, involvement of breast/skin and soft tissue, and surgical cure. Age and median household income showed no association with the median of survival. It can be argued that the deployment of chemotherapy is generally seen in high tumor burden states with systemic metastasis, leading to low overall survival in this category. Given its extremely low incidence, more research and analysis is warranted to understand this lesser-known malignancy.