Development of second primary small‐cell lung cancer within the irradiated field after chemoradiotherapy: a report of two cases

Two male smokers developed small‐cell lung cancer (SCLC) as the second primary malignancy (SPM) in the irradiated field after concurrent chemoradiotherapy for locally advanced cancer, which could also be considered as a radiation‐induced tumour. A 70‐year‐old man received cisplatin and S‐1 and irradiation at 60 Gy for lung adenocarcinoma eight years previously and an 81‐year‐old man cisplatin and 5‐fluorouracil and at irradiation 60 Gy for oesophageal cancer five years previously. They sequentially received chemotherapy for SCLC, the effects of which were limited, and a refractory course was noted. Chemoradiotherapy is an effective treatment strategy for locally advanced cancer but may be relevant to the onset of SCLC as SPM.