Purpose: To determine the prognostic role of comorbidity in Stage III non-small cell lung cancer (NSCLC) treated definitively with radiotherapy alone.
Methods and materials: A total of 112 patients with clinical Stage III NSCLC (American Joint Commission on Cancer 1997) enrolled in four Radiation Therapy Oncology Group studies (83-11, 84-03, 84-07, and 88-08 nonchemotherapy arms) at a single institution were analyzed retrospectively for overall survival (OS) and comorbidity. Of the 112 patients, 105 (94%) completed their assigned radiotherapy. The median assigned dose was 50.4 Gy to the lymphatics (range 45-50.4 Gy) and 70.2 Gy to the primary tumor (range 60-79.2 Gy). Comorbidity was rated retrospectively using the Cumulative Illness Rating Scale for Geriatrics (CIRS-G) and Charlson scales. Karnofsky performance scores (KPSs) and weight loss were prospectively recorded. Because only 8 patients had a KPS of <70, these patients were combined with patients who had a KPS of 70. The OS of this group was compared with that of the patients with better KPSs (>70).
Results: The median survival was 10.39 months (range 7.87-12.91). The 2-, 3-, and 5-year OS rate was 20.5%, 12.5%, and 7.1%, respectively. On univariate analysis, clinical stage (IIIA vs. IIIB) was found to be a statistically significant factor influencing OS (p = 0.026), and the histologic features, grade, tumor size as measured on CT scans, age, tobacco use, weight loss >or=5%, and total dose delivered to the primary tumor were not. A KPS of <or=70 (p = 0.001), the presence of a CIRS-G score of 4 (extremely severe; p = 0.0002), and a severity index of >2 (p <0.0001) were associated with statistically significant inferior OS. Multivariate analysis with clinical stage, KPS, and comorbidity (severity index) of all patients showed that a KPS <or=70 and severity index >2 were independently associated with inferior OS; clinical tumor stage was not found to be an independent prognostic factor.
Conclusion: KPS and comorbidity are important independent prognostic factors in Stage III NSCLC. Comorbidity should be included in protocols studying advanced stage NSCLC and used for stratification.