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Objective:To investigate the role of concurrent chemoradiotherapy in the treatment of limited-stage small cell lung cancer (LS-SCLC) and the impact of the number of chemotherapy cycle during radiotherapy (RT) on clinical prognosis.Methods:Patients with LS-SCLC treated with definitive radiotherapy from May, 2008 to September, 2016 were included in the study. The primary endpoint was overall survival (OS), which was calculated from the start of treatment to the date of death or last follow-up. The effect of the number of concurrent chemotherapy cycle and other clinical factors on clinical efficacy was analyzed. Survival analysis was performed with Kaplan- Meier method, and multivariate analysis was performed with Cox regression model. Results:Three hundred and seventeen patients were eligible for the analysis. Among them, 129 patients received sequential chemoradiotherapy and 188 patients received concurrent chemoradiotherapy. Among patients receiving concurrent chemoradiotherapy, 86 patients received 1 cycle of concurrent chemotherapy and 102 cases of 2 cycles of concurrent chemotherapy. The median follow-up time was 22.47 months. Multivariate survival analysis showed that only clinical stage, timing of RT administration and prophylactic cranial irradiation (PCI) were the independent prognostic factor for OS. The median OS in patients who received 1 cycle and 2 cycles of concurrent chemotherapy during RT were 33.8 months and 30.4 months ( P=0.400). No matter in elder patients or in younger patients, in early RT group or in late RT group and application of PCI or not, the number of concurrent chemotherapy cycle exerted no significant impact on OS. The incidence of grade 3 or above adverse events was 20% in the 1-cycle concurrent chemotherapy group, and 13.7% in the 2-cycle concurrent chemotherapy group. Conclusions:Concurrent chemoradiotherapy is the standard treatment of LS-SCLC. Two cycles of concurrent chemotherapy during RT is not necessarily superior to 1 cycle of concurrent chemotherapy. The optimal number of concurrent chemotherapy cycle during RT need to be studied in a large prospective randomized clinical trial.
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Objective To preliminarily observe the clinical efficacy of hippocampal-sparing prophylactic cranial irradiation (HS-PCI) using helical tomotherapy (HT) in patients with limited-stage small-cell lung cancer (LS-SCLC) after chemoradiotherapy,and compare HT with intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) in dose distribution.Methods From April to June,2014,six patients with LS-SCLC who had achieved a complete remission after chemoradiotherapy were assigned to HS-PCI using HT within a month after brain metastasis was ruled out using brain magnetic resonance imaging (MRI).After fusing CT images and MRI images,the hippocampus was contoured in the fusion images and hippocampal avoidance regions were created using a volumetric expansion of 3 mm around the hippocampus.A dose of 25 Gy in 10 fractions to 95％ of planning target volume (PTV) was prescribed in HT,IMRT,and VMAT.The clinical efficacy,adverse reactions,neurocognitive function,and brain metastasis were evaluated for HT.The dose distribution in PTV and hippocampus were compared between HT,IMRT,and VMAT.Results There were one patient with abdominal wall and abdominal lymph node metastases,one patient with local recurrence,and no patient with brain metastasis during the observation period.The numbers of patients with grade 1 and grade 2 headache,dizziness,and hair loss reactions were 3 and 1,3 and 1,and 4 and 2,respectively.There were no significant differences in the average score of the Mini-Mental State Examination before treatment and at 3 and 6 months after treatment (29.7,29.2,and 29.3 ; P =0.083,0.317,and 0.157).The mean dose to the hippocampus was 16.85 Gy for IMRT and 17.59 Gy for VMAT.For HT,the mean doses to the hippocampus and avoidance regions were reduced to 5.26 Gy and 6.21 Gy,respectively.The prescribed dose for HT was reduced by 79％ and 71％ compared with IMRT and VMAT,respectively.The average coverage rate of the prescribed dose was 94.48％ for HT.Conclusions HT achieves promising dose distribution and target coverage in sparing of the hippocampus.Moreover,HT dose not increase the incidence of adverse reactions.The change in neurocognitive function needs to be further studied with longterm observation and large-scale sampling.