Epidemiologic Features and Age-Related Differences in Management among Patients with Gastrointestinal Stromal Tumors in Japan: A National Cancer Registry Study.

Data on the epidemiology of gastrointestinal stromal tumor (GIST) and differences in its management according to age group are limited in Japan. We aimed to conduct an epidemiologic evaluation and describe age-related differences in management using data from Japan's National Cancer Registry. We analyzed National Cancer Registry data of 21,426 patients with GIST between 2016 and 2019. We compared information on demographics, treatment, and prognosis across three age groups: pediatric and adolescent young adult (PAYA; ≤39 years), adult (40-74 years), and geriatric (≥75 years). Crude and age-adjusted annual incidences of GIST were 4.23 and 4.20 per 100,000 population, respectively. Regional variations in average age-adjusted annual incidence were observed among prefectures. The most common primary organs were stomach (72%), followed by the small intestine (21%). Geriatric patients represented 33% of the total population. Relative to PAYA and adult patients, geriatric patients were less likely to undergo surgery in the nonmetastatic setting (PAYA, 93%; adult, 93%; and geriatric, 87%; P < 0.001) or to receive chemotherapy in the metastatic setting (PAYA, 90%; adult, 87%; and geriatric, 61%; P < 0.001). Geriatric patients showed poorer 2-year overall survival relative to PAYA and adult patients in the nonmetastatic (PAYA, 98.5%; adult, 97.2%; and geriatric, 89.2%; P < 0.001) and metastatic (PAYA, 92.9%; adult, 79.2%; and geriatric, 54.7%; P < 0.001) settings. Geriatric patients comprised one third of the study population and were associated with less active treatment and an unfavorable prognosis. SIGNIFICANCE: This is the first report presenting comprehensive Japanese epidemiologic data on GIST at a national level.