Prognostic value of age in patients with inoperable stage Ⅲ non-small cell lung cancer after radiotherapy: a competing risk analysis based on the Surveillance, Epidemiology, and End Results database / 肿瘤研究与临床

ABSTRACT

Objective:To explore the data of patients with inoperable stage Ⅲ non-small cell lung cancer (NSCLC) after radiotherapy from the Surveillance, Epidemiology, and End Results (SEER) database, and to evaluate the effect of age on prognosis.Methods:The data of patients with inoperable stage Ⅲ A and Ⅲ B NSCLC according to the 7th edition of the American Joint Committee on Cancer (AJCC) staging standard who had been treated with radiotherapy from 2010 to 2016 were collected in the SEER database. A total of 17 117 cases were included in the analysis. According to the maximally selected test, the best cut-off value of age was 72 years old. According to the best cut-off value of age, patients were divided into the young group (< 72 years old, 11 008 cases) and the elderly group (≥ 72 years old, 6 109 cases). The basic clinical characteristics were compared between the two groups. Kaplan-Meier method was used to analyze the overall survival (OS) and log-rank test was performed. The multivariate Cox proportional hazards regression model was used to analyze the influencing factors for OS. The cumulative incidence function (CIF) was used to calculate the lung cancer-specific death rate and death rate from other causes in the different age groups, and the difference between the two groups was compared by Fine-Gray competing risk model, and the influencing factors of lung cancer-specific death were analyzed. Results:The proportion of squamous cell carcinoma in the elderly group was higher than that in the young group [51.1% (3 123/6 109) vs. 46.8% (5 154/11 008), P < 0.01], and the proportion of stage Ⅲ A was also higher than that in the young group [67.4% (4 120/6 109) vs. 60.1% (6 615/11 008), P < 0.01]; the proportion of patients receiving chemotherapy in the elderly group was lower than that in the young group [69.2% (4 226/6 109) vs. 88.6% (9 748/11 008), P < 0.01]. The 2-year and 5-year OS rates of the young group were 39.2% and 18.0%, and the elderly group were 32.4% and 12.5% (both P < 0.01). The multivariate Cox regression analysis showed that age, gender, race, year of diagnosis, pathological type, T stage, N stage, reason for non-operation and chemotherapy were independent influencing factors for patients' OS after radiotherapy, and among them, HR of age (≥ 72 years old vs. < 72 years old) was 1.13 (95% CI 1.09-1.18) ( P <0.01). The 2-year and 5-year cumulative incidence rate of lung cancer-specific death in the elderly group were 60.3% and 75.7%, which were higher than the corresponding values of 55.9% and 74.0% in the young group, and the difference of cumulative incidence rate of lung cancer-specific death between the two groups was statistically significant ( P < 0.01). The 2-year and 5-year cumulative incidence rate of death from other causes in the elderly group were 7.3% and 11.8%, which were higher than the corresponding values of 4.9% and 8.0% in the young group, and the difference of death from other causes between the two groups was statistically significant ( P < 0.01). The competing risk model analysis showed that age, gender, race, year of diagnosis, pathological type, T stage, N stage, and with or without chemotherapy were independent influencing factors for lung cancer-specific death in patients with inoperable stage Ⅲ NSCLC after radiotherapy, and among them, HR of age (≥ 72 years old vs. < 72 years old) was 1.07 (95% CI 1.02-1.12) ( P =0.002). Conclusions:Age is an independent prognostic factor for patients with inoperable stage Ⅲ NSCLC after radiotherapy. The prognosis of elderly patients is poor, and they have high risks of lung cancer-specific death and death from other causes.