P1.07-021 Impact on Survival of High Dose Consolidative Thoracic Radiotherapy in Extensive Stage Small Cell Lung Cancer

Abstract

Consolidative thoracic radiotherapy for metastatic small cell lung cancer patients who have responded to chemotherapy is controversial. Some publications suggest improved local control which could influence survival. Slotman et al. have recently published a randomized study that showed that thoracic radiotherapy improves long term survival for patients with extensive stage small cell lung cancer (ES-SCLC) who have responded to chemotherapy. Slotman also demonstrated in 2007 that prophylactic cranial irradiation in metastatic small-cell lung cancer with response to initial chemotherapy, reduces the incidence of symptomatic brain metastases and prolongs disease-free and overall survival. In our Radiation Oncology Department we have reviewed those patients with ES-SCLC (disseminated disease excluding brain metastases) who have achieved an objective response after chemotherapy, received prophylactic cranial irradiation and, after that, some of them treated with consolidative thoracic radiotherapy (CRT). Between 1995 and 2015 we have treated 68 patients, 59 men and 9 women (median age 63 years, range 42-79), with the characteristics mentioned above. Prophylactic cranial irradiation was administered at median doses of 24 Gy (range 24-36 Gy). Thoracic radiotherapy consolidation was delivered to 23 patients (33.8 %), with a median total dose of 46 Gy (range 20-54 Gy). We compared this group with the 45 patients (66.2%) who did not receive CRT. Among those patients treated with CRT, 17 patients (74%) had residual disease after chemotherapy, 4 patients (17.4%) had chest progression and 2 patients (8.7%) achieved complete response. No grade 3 toxicity has been reported. Median overall survival (OS) is 18 months in patients who received CRT, compared to 10 months in those patients who have not CRT. OS after one year was 78.3% in the group of patients with CRT and 41.3% when CRT was not performed. OS after two years was 34.8% with CRT and 6.9% without CRT. We have found a benefit (p=0.002) in the group of patients who received CRT, compared with patients who did not, obtaining significant differences in median survival and overall survival, taking into account that a bias selection could have affected the results. In comparison with Slotman study, we have found an improved survival with higher doses of CRT, without additional severe toxicity.