Analysis of Real World Data To Evaluate Survival Benefit of Radiation Therapy in Stage III / N2 Non-Small Cell Lung Cancer

Abstract

The clinical benefit of radiation therapy for patients with locally advanced stage III (N2) Non-Small Cell Lung Cancer (NSCLC) treated with surgery remains unclear due to a paucity of level 1 evidence. This study examined real-world evidence using a cohort of NSCLC patients from a multi-institution dataset to evaluate outcomes in patient treated with surgery alone, neoadjuvant or adjuvant radiation therapy. We extracted a sample of 415 fully-abstracted patients with pathologic stage III (N2) NSCLC defined at the initial surgical intervention performed within 6 months of initial diagnosis. Two- and five-year survival outcomes were evaluated for patients who received radiation neoadjuvant, adjuvant (PORT), or no radiation therapy. Sub-analyses and normalization of treatment groups were performed including use of chemotherapy, targeted therapy and IO therapy as well as age and gender using Cox proportionate hazards. Of the 415 patients evaluated, 54% (n=206) were treated with surgery alone, 16% (n=66) neoadjuvant radiation therapy and 34% (n=143) adjuvant radiation therapy. Chemotherapy use for patients across groups was balanced, 68% (n=140), 83% (n=56), 72% (n=103) for patient treated with surgery, neoadjuvant or adjuvant radiation therapy, respectively. Patients who received neoadjuvant radiation therapy had a 45% reduction in 2-year mortality risk (HR = .55, 95% CI 0.35 - 0.89), compared to patients treated with surgery alone (HR = 0.59, 95% CI .37 - 0.93). Radiation therapy did not improve 5-year mortality risk except in female patients, who show a 48% reduction in mortality risk at 5-years from radiation therapy pre- or post-operatively (HR = .52, 95% CI .29 - .94). There was no statistically significant difference in survival outcomes for patients treated with adjuvant radiation therapy, compared to surgery alone. Analysis of 415 abstracted patients this dataset suggests that the addition of preoperative radiation therapy improves 2 and 5-year survival for patients with pathologic stage III (N2) NSCLC, compared to patients treated with surgery alone. A significant survival benefit was not observed for adjuvant radiation therapy, however surgical margin status, performance status, and incidence of comorbidities was not included in the analysis due to the lack of granularity of the retrospective data.Abstract 3222; Table 1Surgery Only / No Radiation TherapyNeoadjuvant Radiation TherapyAdjuvant Radiation TherapyAll PatientsTotal (n)2-Year OS5-year OSTotal (n)2-Year OS5-Year OSTotal(n)2-Year OS5-Year OSTotal (n)2-Year OS5-Year OSAll patients20677%67%6692%86%14384%76%41582%71%Age >= 6015177%66%4994%78%10083%75%30082%71%Age < 605578%67%1712%71%4386%77%11583%71%Male10977%64%3090%70%7077%66%20979%66%Female9777%69%3694%81%7390%85%20685%77%Chemotherapy14076%74%5591%73%10380%70%29880%68%Neoadjuvant chemotherapy3093%87%4489%76%1090%80%8590%81%No chemotherapy6680%71%11100%91%4095%90%11787%79% Open table in a new tab