Response to combined modality therapy correlates with survival in locally advanced non-small-cell lung cancer

Purpose: Although concurrent chemoradiotherapy can now achieve demonstrated long-term survival in patients with locally advanced non-small-cell lung cancer (LANSCLC), it is difficult to predict which patients will benefit most from this therapeutic approach. Studies have suggested that local control, and the response to therapy, may be linked to improved survival; however, detailed analysis of the impact of tumor response to chemoradiotherapy on survival has not been thoroughly reported. Therefore, we sought to determine the impact of the response rate on survival for patients who were treated with combined modality therapy for LANSCLC. Methods and Materials: We reviewed the data from 116 patients enrolled between 1994 and 1997 in three trials investigating paclitaxel-based concurrent chemoradiotherapy for LANSCLC. Tumor size measurements were assessed immediately before and 2 months after completion of combined modality therapy to determine the response and to calculate the percentage of decrease in tumor size. Results: Patients with a response (complete or partial) had an improved 4-year overall survival rate compared with patients with no response (stable or progressive disease; 21.1% vs. 3.3%, p <0.0001) in the 109 assessable patients. Progression-free survival also improved significantly with response. An analysis of the percentage of decrease in tumor size vs. survival was performed (n = 74) using Cox proportion model analysis. After combined modality therapy, a 20%, 40%, 60%, 80%, and 100% decrease in tumor size conferred a 39%, 63%, 78%, 86%, and 92% reduction in risk of death compared with a 0% decrease in tumor size (p <0.0001). Conclusion: The response by conventional response criteria correlated strongly with improved overall survival and progression-free survival and an increasing percentage of decrease in tumor size resulted in a reduction in the risk of death. Additional investigation of the degree of response as a factor predictive of improved therapeutic efficacy, translating into improved survival, is warranted.