PV QA 4 - Poster Viewing Q&A 4
TU_31_3629 - Association between Tumor Laterality and Cardiac Mortality in Patients with Non-Small Cell Lung Cancer Treated with Radiation
Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3
Association between Tumor Laterality and Cardiac Mortality in Patients with Non-Small Cell Lung Cancer Treated with Radiation
V. Muralidhar1, R. B. Jimenez2, M. J. Khandekar3, C. G. Azzoli4, T. G. Neilan3, and F. K. Keane5; 1Harvard Radiation Oncology Program, Boston, MA, 2Department of Radiation Oncology, Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, 3Massachusetts General Hospital, Boston, MA, 4Massachusetts General Hospital Cancer Center, Boston, MA, 5Harvard Radiation Oncology Program, Harvard Medical School, Boston, MA
Purpose/Objective(s): Prior work has suggested that tumor laterality can influence cardiac radiation dose in patients with non-small cell lung cancer (NSCLC) treated with radiation therapy (RT). Other data have suggested a relationship between tumor laterality and cardiac mortality in Stage III NSCLC. However, there are limited data on the impact of tumor laterality on cardiac mortality in Stage I – II NSCLC. We sought to determine whether tumor laterality is associated with increased cardiac mortality among all patients with non-metastatic NSCLC treated with RT. Materials/Methods: We identified 67,048 patients with non-metastatic NSCLC treated with external beam radiation therapy diagnosed between 1988 and 2014 using the Surveillance, Epidemiology, and End Results (SEER) database. We used Fine-Gray competing risks regression to model the impact of tumor laterality (left vs right) on cardiac mortality after adjusting for sex, year of diagnosis, tumor grade, stage, age at diagnosis, race, marital status, education level, income level, receipt of chemotherapy, and receipt of surgery. We also performed subgroup analyses by tumor stage, lobar location, and year of diagnosis. Results: With a median follow-up of 7.8 years, patients with left-sided tumors had a significantly increased risk of 5-year cardiac mortality compared to those with right-sided tumors (4.1% vs 3.4%, adjusted hazard ratio [AHR] 1.18, 95% confidence interval [CI] 1.10 to 1.27, p < 0.001). This difference was driven mainly by tumors in the left lower lobe (AHR 1.32 compared to right-sided tumors, p < 0.001). In subgroup analyses stratified by AJCC stage, the effect of tumor laterality (left vs right) was present among those with stage I (AHR 1.18, p = 0.029), stage II (AHR 1.29, p = 0.002), and stage III NSCLC (AHR 1.17, p = 0.001). Among those treated in 1988-2004, the effect of tumor laterality on 5-year cardiac mortality was larger (4.2% vs 3.4%, AHR 1.24, p < 0.001) compared to those treated in 2005-2014 (3.9% vs 3.5%, AHR 1.13, p = 0.038). Conclusion: Patients with left-sided NSCLC treated with RT are at higher risk of cardiac mortality compared to those with right-sided NSCLC across stages I-III, especially for those with left lower lobe primary tumors. The effect of tumor laterality was less pronounced in more recent years, potentially due to the development of more conformal RT techniques. Combined with the results of the RTOG 0617 trial, these findings raise the possibility that cardiac radiation dose is an important driver of cardiac mortality following thoracic RT for NSCLC. Further research is needed to determine optimal cardiac dose constraints to minimize the risk of cardiac toxicity with RT, as well as to develop techniques to further minimize RT to the heart.
Author Disclosure: V. Muralidhar: None. R.B. Jimenez: None. M.J. Khandekar: None. C.G. Azzoli: None. T.G. Neilan: Consultant; Takeda. F.K. Keane: None.