Impact of Comorbidities on Acute Toxicity in Patients Receiving Radiation Therapy for Locally Advanced Lung Cancer

Abstract

Patients with advanced lung cancer often have multiple medical comorbidities; however, it is not well known if comorbidity burden impacts tolerance of thoracic radiation treatment (TRT). We hypothesized that patients with more comorbidities are more likely to experience acute toxicity from TRT for locally advanced lung cancer. We queried two patient databases: data from four prospective institutional investigator-initiated trials (IIT) as well as data from a large multicenter state-wide quality consortium. To assess comorbidities, we used the Charlson Comorbidity Index (CCI) for the IIT cohort and created a Comorbidity Index (CI) using similar, available data for the consortium cohort. Logistic regression was used to determine the relationship between comorbidity indices and radiation-induced toxicities, specifically grade≥2 esophagitis and pneumonitis. Adjustments were made for PTV volume, concurrent chemotherapy, and radiation dose to organs at risk. Weighting variables were applied for consortium patients for modeling pneumonitis outcome because of heterogeneity in follow-up time. A total of 1188 patients were analyzed in the IIT and consortium cohorts (112 and 1076, respectively), with average age 65 and 67 years and PTV volume of 465 and 369 mL. Total incidence of grade ≥2 radiation pneumonitis was 13.5% and 6.8%, and grade ≥2 esophagitis was 41.4% and 54.3%, respectively, for the IIT and consortium cohorts. Mean CCI for the IIT cohort was 3.7; mean CI for the consortium cohort was 1.5. The data were concordant that there is no evidence linking comorbidity indices to any toxicity outcome (Table 1). Esophagitis was significantly associated with concurrent chemotherapy (p<0.0001 in the consortium cohort, NS in the IIT cohort) and mean esophageal dose (p<0.0001 in the consortium cohort and p=0.04 in the IIT cohort). Pneumonitis was also significantly related to mean lung dose in the IIT cohort (p=0.04). This is the largest study using prospectively-collected data of lung cancer patients treated with definitive TRT evaluating comorbidity burden and radiation-induced acute toxicity. As an independent variable, comorbidity indices are not associated with higher rates of esophagitis or pneumonitis in lung cancer patients undergoing TRT. This suggests that treatment-related rather than patient-specific factors are most important in determining the toxicity profile for these patients.Abstract TU_30_3622; Table 1Effect of Clinical Variables on Radiation-Induced ToxicitiesEsophagitisPneumonitisOdds Ratio (OR) and p-value (p)ConsortiumIITConsortiumIITVariableORpORpORpORpPTV vol.1.00.920.910.281.10.171.10.43Conc. Chemo2.5<0.00015.80.111.10.891.30.81Mean Esophagus Dose1.1<0.00011.10.04----Mean Lung Dose----1.10.111.20.04Comorbidity Index1.00.430.940.671.00.980.680.11 Open table in a new tab