Abstract: ［Abstract］〓Objective〖HTSS〗〓To compare the benefits and tolerance of radiotherapy patients with limitedstage small cell lung cancer(LSSCLC) in different EP cycles, and to explore the timing of radiotherapy.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓The patients with limited stage small cell lung cancer confirmed by pathology were randomly divided into two groups. Group A: VP16 120 mg/m2 d1, 2, 3, cisplatin 60 mg/m2 d1, every 3 weeks for 1 cycles, a total of 4 cycles. In first cycles of concurrent radiotherapy, radiotherapy dose and schedule: 45 GY(1.5 GY, bid) for three weeks. Group B: VP16 120 mg/m2 d1, 2, 3, cisplatin 60 mg/m2 d1, every 3 weeks for 1 cycles, a total of 4 cycles. In second cycles of concurrent radiotherapy, radiotherapy dose and schedule: 45 GY(1.5 GY, bid) for three weeks. Each group received intravenous granisetron and antiemetic therapy 30 minutes before the treatment.The observation indexes were remission rate(RR), disease control rate(DCR), progression free survival(PFS), and the adverse reactions of circulating tumor cells(CTC) number.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓The RR and DCR of group A and group B were not statistically significant(P>0.05). The PFS and average survival time of group A were longer than gruop B, the difference was statistically significant(P＜005). In the adverse reactions, the incidence of esophagitis in group A was significantly higher than that in group B(P＜005), and the incidence of leukopenia, anemia and thrombocytopenia were similar in both groups, and the incidence of esophagitis in group A was significantly higher than that in group B(P>0.05). CTC was measured in fourth cycle, the number of CTC in group A was significantly lower than that before chemotherapy(P＜005), the number of CTC in patient with CTC≥10 and CTC≥50 is significantly lower than befor in gruop B, but the number of CTC in patient with CTC≥1 and CTC≥5 was not lower than before(P>0.05). The number of CTC≥5 and CTC≥10 in group A was less than that in group B(P＜005). There was no significant difference between CTC≥1 and CTC≥50 in group A(P> 0.05).
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓The EP regimen of the first cycle combined with concurrent radiotherapy is superior to EP regimen in the second cycle of combined radiotherapy.

Key words: small cell lung carcinoma, chemoradiotherapy, treatment outcome