Analysis of the Relationship Between Response to Chemotherapy and Response to Radiation Therapy in Patients With Non-Small Cell Lung Cancer Receiving Sequential Treatment.

Objectives: We examine whether induction chemotherapy response predicts thoracic radiotherapy response in locally advanced or oligometastatic non-small cell lung cancer.
Materials and Methods: Between January 2001 to August 2010, 25 consecutive patients were identified who received systemic dose chemotherapy followed by definitive thoracic radiotherapy alone. All patients had measurable disease after chemotherapy that was evaluable for response to radiotherapy. Response to each modality was scored by RECIST as stable disease (SD), progressive disease (PD), partial response (PR), or complete response (CR).
Results: Patients had adenocarcinoma (n=13), squamous cell carcinoma (n=8), or other histologies (n=4). They had stage IIIA (n=6), IIIB (n=14), and IV (n=5) disease. Patients received 2 to 6 cycles (median 4) of platinum-based chemotherapy followed by radiotherapy (median 66.6/1.8 Gy [range 50 to 84 Gy]). Median time between chemotherapy end and radiotherapy start was 6.7 weeks (range, 1.6 to 53.4 wk). Twelve patients responded to chemotherapy (all were PRs) and 13 did not (SD+PD). Fifteen patients responded to radiotherapy (7 CR, 8 PR) and 10 did not (SD+PD). Of the 12 patients who responded to chemotherapy, 8 also responded to radiotherapy (4 CR, 4 PR). Of the 13 chemotherapy nonresponders, 7 responded to radiotherapy (3 CR, 4 PR). χ analysis did not find any association between chemotherapy and radiotherapy response (P=0.513). Regression analysis also failed to identify any correlation between chemotherapy and radiotherapy response (r=0.008).
Conclusions: This study suggests that response to chemotherapy does not predict response to radiotherapy in locally advanced or oligometastatic non-small cell lung cancer. Lack of response to chemotherapy, therefore, should not preclude treatment with definitive radiotherapy.