Lung Cancer

PV QA 4 - Poster Viewing Q&A 4

TU_31_3622 - Impact of Comorbidities on Acute Toxicity in Patients Receiving Radiation Therapy for Locally Advanced Lung Cancer

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

Impact of Comorbidities on Acute Toxicity in Patients Receiving Radiation Therapy for Locally Advanced Lung Cancer
M. McFarlane1, Y. Sun2, M. Schipper2, C. Maurino1, A. M. Laucis1, A. Saripalli1, R. K. Ten Haken1, F. M. Kong3, M. M. Matuszak1, D. E. Spratt1, L. J. Pierce4, J. A. Hayman4, P. A. Paximadis5, and S. Jolly1; 1Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 2Department of Biostatistics, University of Michigan, Ann Arbor, MI, 3Indiana University Radiation Oncology, Indianapolis, IN, 4Michigan Medicine, Ann Arbor, MI, 5Lakeland Radiation Oncology, St. Joseph, MI

Purpose/Objective(s): 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.

Materials/Methods: 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.

Results: 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).

Conclusion: 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. Table 1: Effect of Clinical Variables on Radiation-Induced Toxicities
Esophagitis Pneumonitis
Odds Ratio (OR) and p-value (p) Consortium IIT Consortium IIT
Variable OR p OR p OR p OR p
PTV vol. 1.0 0.92 0.91 0.28 1.1 0.17 1.1 0.43
Conc. Chemo 2.5 <0.0001 5.8 0.11 1.1 0.89 1.3 0.81
Mean Esophagus Dose 1.1 <0.0001 1.1 0.04 - - - -
Mean Lung Dose - - - - 1.1 0.11 1.2 0.04
Comorbidity Index 1.0 0.43 0.94 0.67 1.0 0.98 0.68 0.11

Author Disclosure: M. McFarlane: None. Y. Sun: None. M. Schipper: None. C. Maurino: None. R.K. Ten Haken: Research Grant; NIH-NCI. Honoraria; University of Copenhagen. Travel Expenses; Varian Medical Systems Inc, University of Copenhagen. F.(. Kong: Research Grant; Varian, NCI/NIH. Founding President and Board of Director; Sino-American Network for Therapeutic Radiation On. President 2015; American Association of Women Radiologists (AAWR). President 2012-2013; Association for Chinese Professors. Founding Board Member; Sino-American Network for Therapeutic Radiology. M.M. Matuszak: Employee; William Beaumont Hospital. L.J. Pierce: Royalty; UpToDate. J.A. Hayman: Research Grant; Blue Cross Blue Shield of Michigan. P.A. Paximadis: None. S. Jolly: None.

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