Concurrent Chemoradiotherapy with Original Chemotherapy Regimens may not be Suitable for Patients Who Failed to Respond to Induction Chemotherapy in Limited-stage Small Cell Lung Cancer

Background and objective The group of small cell lung cancer (SCLC) are usually highly sensitive to chemotherapy, and less than 15% of them are resistant to drugs. We respectively evaluate the correlation of the sequence and timing of radiotherapy with progression-free survival (PFS) and overall survival (OS) in patients with limited-stage SCLC (LS-SCLC), and to figure out whether concurrent chemoradiotherapy is superior to sequent chemoradiotherapy. Methods Sixty-seven patients diagnosed with LS-SCLC from January 2009 to June 2014 failed to respond to induction chemotherapy. According to the sequence of therapy, they were divided into concurrent chemoradiotherapy group (n=32) and sequent chemoradiotherapy group (n=35). Ninety-four percent of the patients were diagnosed with stage III, and six percent were stage Ib-IIb. Twenty-five patients were treated with prophylactic cranial irradiation (PCI). The Kaplan-Meier method was used to calculate survival time and Log-rank test was used for between-group comparisons. Between-group comparison of categorical data was made by χ2 test. Results In all patients, the 2-year OS, PFS and LC rates were 53.7%, 20.9% and 58.2%. The 2-year OS and PFS rates of concurrent chemoradiotherapy group and sequent chemoradiotherapy were 37.5% vs 54.3% (P=0.048) and 12.5% vs 28.6% (P=0.149). Hematologic toxicities were more common in concurrent group than sequent one (P=0.031), and no statistical difference was observed between the two groups in terms of grade 3 radiation esophagitis, pneumonitis and gastrointestinal reactions (9.4% vs 0, P=0.176; 12.5% vs 2.9%, P=0.318; 12.5% vs 2.9%, P=0.109). Patients treated with PCI have superior OS and PFS comparing with those not (56.0% vs 38.1%, P=0.029; 24% vs 19%, P=0.012). Conclusion Concurrent chemoradiotherapy with original chemotherapy regimens may not be suitable for patients who failed to respond to induction chemotherapy in LS-SCLC, and second-line regimens or radiotherapy alone can be used for them, but prospective trils with large sample are still needed to confirm that.