Thoracic Radiation in Limited Stage Small Cell Lung Cancer: Trends in Radiation Fractionation

Thoracic radiotherapy (TRT) is standard of care for limited-stage small cell lung cancer (LS-SCLC). Although initial data supported the use of twice-daily (BID) radiation to a dose of 45 Gy, recent trials have suggested similar efficacy with daily fractionation (QD) to a dose of 60 to 70 Gy. This study evaluates trends in treatment regimen in patients treated with TRT for LS-SCLC.

The National Cancer Database (NCDB) was queried for patients with LS-SCLC treated with TRT between 2004 to 2017 grouped by RT fractionation QD vs. BID. Exclusion criteria were unknown stage, and unknown RT dose. Multivariable (MVA) analyses using logistic regression were performed to investigate factors associated with receipt of a specific fractionation schedule.

A total of 17,453 patients met inclusion criteria, with 4,996 receiving BID treatment and 12,457 receiving QD treatment. The most common QD dose was 60 Gy (48.9%). Overall, QD fractionation has increased (1.3%/year). In 2004, 45 Gy BID treatment (41.4%) was the dominant fractionation. By 2017, 60 Gy QD (45.2%) increased (1.9%/y) to be the dominant fractionation, while 45 Gy BID (24.8%) decreased (-1.4%/y) to be the second most common fractionation. On MVA, factors that affect 1 treatment over the other were further stratified.

Since 2004, QD fractionation has been the preferred TRT regimen for patients with LS-SCLC compared to BID fractionation, with the proportion of patients getting QD treatment continuing to increase. The choice of treatment regimen appears to be influenced by both patient and facility characteristics.