Differences between lung adenocarcinoma and squamous cell carcinoma in histological distribution of residual tumor after induction chemoradiotherapy

Aims To facilitate dose planning for convergent beam radiotherapy in non-small cell lung cancer (NSCLC), tumor response and histological distribution of residual tumors after induction chemoradiotherapy (ICRT) were compared between adenocarcinoma (AD) and squamous cell carcinoma (SQ). Methods Ninety-five patients with N1–2 or T3–4 NSCLC were treated with ICRT followed by surgery; 55 had AD and 40 had SQ. For the evaluation of distribution of residual tumors, the location of the external margin of residual tumors was assessed on surgical materials as follows: radius of whole tumor (“a”); distance between the center of tumor and the external margin of residual tumor (“b”); and its location (“b/a”). Results Of the 55 AD cases, 8 (15%) showed pathological complete remission, which was significantly less frequent than 22 of 40 SQ cases (55%) (p