Effect of Thoracic Radiotherapy Timing and Fractionation on Survival in Nonmetastatic Small Cell Lung Carcinoma.

BACKGROUND

The optimal timing of thoracic radiation therapy (RT) in relation to chemotherapy is unknown in the treatment of nonmetastatic small cell lung cancer (SCLC). We analyzed the National Cancer Data Base (NCDB) to assess the effect on overall survival (OS) of RT timing with chemotherapy for patients with SCLC.

MATERIALS AND METHODS

The NCDB was queried for patients diagnosed with nonmetastatic SCLC from 1998 to 2011 who had undergone definitive chemoradiation. The patients were stratified into quartiles according to the interval between the start of chemotherapy and the start of RT. The first and second quartiles (RT started 0-20 days after chemotherapy) were classified as "early" RT and the third and fourth quartiles (RT started 21-126 days after chemotherapy) as "late" RT. Patients were included if they had received hyperfractionated 45 Gy in 30 fractions or standard fractionation of ≥ 60 Gy in 1.8- to 2-Gy fractions. Kaplan-Meier analyses of OS were performed, and multivariable Cox regression analysis was conducted to assess the effect of the covariates on OS.

RESULTS

A total of 8391 patients were included (50.5% had received early RT). Early RT was associated with significant improvement in survival (5-year OS, 21.9% vs. 19.1%; P = .01). On subgroup analysis, the survival advantage for early RT was significant for patients receiving hyperfractionated RT (5-year OS, 28.2% vs. 21.2%; P = .004) but not for those receiving standard fractionation (19.8% vs. 18.4%; P = .29). On multivariable Cox regression analysis, hyperfractionated RT was associated with reduced mortality (hazard ratio [HR], 0.90; 95% confidence interval [CI], 0.85-0.96; P = .001), but early RT was not (HR, 0.98; 95% CI, 0.94-1.04; P = .53).

CONCLUSION

These data support the early initiation of hyperfractionated thoracic RT for nonmetastatic SCLC.