The changing landscape of small cell lung cancer.

BACKGROUND: Small-cell lung cancer (SCLC) is characterized by rapid proliferation and early dissemination. The objective of this study was to examine the demographic trends and outcomes in SCLC.

METHODS: The authors queried the National Cancer Institute's Surveillance, Epidemiology, and End Results database to assess the trends in incidence, demographics, staging, and survival for SCLC from 1975 to 2019. Trends were determined using joinpoint analysis according to the year of diagnosis.

RESULTS: Among the 530,198 patients with lung cancer, there were 73,362 (13.8%) with SCLC. The incidence per 100,000 population peaked at 15.3 in 1986 followed by a decline to 6.5 in 2019. The percentage of SCLC among all lung tumors increased from 13.3% in 1975 to a peak of 17.5% in 1986, declining to 11.1% by 2019. There was an increased median age at diagnosis from 63 to 69 years and an increased percentage of women from 31.4% to 51.2%. The percentage of stage IV increased from 58.6% in 1988 to 70.8% in 2010, without further increase. The most common sites of metastasis at diagnosis were mediastinal lymph nodes (75.3%) liver (31.6%), bone (23.7%), and brain (16.4%). The 1-year and 5-year overall survival rate increased from 23% and 3.6%, respectively, in 1975-1979 to 30.8% and 6.8%, respectively, in 2010-2019.

CONCLUSIONS: The incidence of SCLC peaked in 1988 followed by a gradual decline. Other notable changes include increased median age at diagnosis, the percentage of women, and the percentage of stage IV at diagnosis. The improvement in 5-year overall survival has been statistically significant but clinically modest.