Outcomes of extensive stage extrapulmonary small cell cancer

Abstract Background Extrapulmonary small cell cancer (EPSCC) is a rare malignancy with an incidence of approximately 0.1%–0.4% of all cancers. Treatment of this disease is often based on small cell lung cancer. Aims We aimed to investigate real‐world clinical outcomes of patients with extensive‐stage (ES) ESPCC. Methods Patients diagnosed with ES EPSCC between 2010 and 2020 from multiple centres in New South Wales were identified. Patient, disease and treatment characteristics were collected and presented using descriptive statistics. Survival was analysed using the Kaplan–Meier method. Univariate and multivariate Cox regression hazard models were used to identify potential prognostic factors. Results Sixty eligible ES EPSCC patients were identified, including 65% male and 35% female. The mean age was 69 years (range 37–88). Forty‐five per cent were never smokers, 42% ex‐smokers and 13% current smokers, and 17% of patients had limited‐stage disease prior to development of ES disease. The most common primary sites were genitourinary (42%; mainly prostate ( n = 14) and bladder ( n = 10)), gastrointestinal (28%; mainly oesophagus ( n = 5) and colon ( n = 4)) and unknown primary (22%). Treatments received included palliative chemotherapy (67%), palliative radiotherapy (53%), palliative surgery (13%) and best supportive care alone (13%). The median overall survival (OS) was 8.0 months. The median progression‐free survival was 5.4 months, and response rate to first‐line chemotherapy was 65%. Platinum‐based chemotherapy was prognostic of longer OS (HR 0.27, CI 0.12–0.60, P = 0.001). Conclusions Patients with ES EPSCC had good response to palliative chemotherapy, but OS remained poor. Further research is required to improve the prognosis in this population.