Tumor size does not predict pathological complete response rates after pre-operative chemoradiotherapy for non-small cell lung cancer.

Objective To evaluate in a cohort of superior sulcus tumors (SST) whether even large tumors can respond well to chemoradiotherapy and can be sterilized with modest doses of radiotherapy (45-50 Gy). Methods Patients with SST, treated with trimodality therapy at our institution between 2002 and 2011, who received 45-50 Gy radiotherapy, were included. Resection specimens were examined for remaining vital tumor cells. The maximum axial and cranio-caudal tumor diameters were measured on the radiotherapy planning scan images and reviewed by four authors. The primary tumor was contoured by one author and reviewed by a second to obtain gross tumor volume (GTV). Results Twelve out of 36 included patients had a pathological complete response (pCR). No significant differences were seen in tumor measurements between patients with and without a pCR. Logistic regression analysis demonstrated that neither maximum axial diameter, nor cranio-caudal diameter or GTV were predictive for pCR. The area under the ROC-curve for prediction of pCR was 0.41 (P = 0.45) for maximum axial diameter, 0.39 (P = 0.37) for cranio-caudal diameter and 0.33 (P = 0.15) for GTV. Conclusions Large tumor size or volume near the beginning of induction chemoradiotherapy does not preclude a complete pathological response in SST patients.