Abstract 3331: Association of lifestyle and clinical characteristics with receipt of radiotherapy treatment among women diagnosed with DCIS in the National Institutes of Health-AARP Diet and Health Cohort Study
Authors: Mullooly Maeve , Withrow Diana R. , Curtis Rochelle E. , Fan Shaoqi , Liao Linda M. , Pfeiffer Ruth M. , Gonzalez Amy Berrington de , Gierach Gretchen L. 
Published: August 2019

Introduction: The long-term risks and benefits of breast radiotherapy for the treatment of ductal carcinoma in situ (DCIS) remain unclear. A recent study using data from the Surveillance, Epidemiology and End Results (SEER) registries showed that DCIS-associated radiotherapy treatment significantly increased risks of second non-breast cancers. To help disentangle those observations and understand whether breast cancer risk factors are related to radiotherapy treatment decision making, we aimed to identify factors associated with receipt of radiotherapy treatment for DCIS.

Methods: Accordingly, among 1,628 women with DCIS who participated in the large prospective National Institutes of Health (NIH)-AARP (formerly American Association of Retired Persons) Diet and Health Cohort Study, that were diagnosed between study entry and follow up (through 31st December 2011) and eligible for inclusion, we examined associations between demographic, lifestyle and clinical factors and receipt of radiotherapy treatment. Odds ratios and 95% confidence intervals (CIs) were estimated from multivariable logistic regression models, to determine associations.

Results: Among women diagnosed with DCIS, 45% (n=730) received radiotherapy treatment. No relationships were observed between receipt of radiotherapy and lifestyle factors including smoking status. The strongest associations were observed for clinical factors. Receipt of radiotherapy was associated with a more recent diagnoses period (2005-2011 versus 1995-1999; OR=1.60, 95%CI: 1.14, 2.25), diagnosis within eastern (Michigan/New Jersey) versus western US states, (OR=1.44, 95%CI: 1.07, 1.93), poorly than well-differentiated tumours (OR=1.69, 95%CI: 1.16, 2.46) and receipt of endocrine therapy (OR=3.37, 95%CI: 2.56, 4.44).

Discussion: Clinical characteristics of the DCIS and temporal trends in radiotherapy use were the strongest determinants of radiotherapy treatment within this population. Receipt of radiotherapy was largely unrelated to lifestyle factors suggesting that the previously observed associations in SEER between radiotherapy treatment and risk of non-breast cancers were likely not confounded by lifestyle factors including smoking status. Thus, these findings are relevant for understanding the aetiology of subsequent secondary cancers among the increasing population of DCIS survivors. The lack of association observed for breast cancer family history and prior breast biopsy suggest that these risk factors do not influence radiotherapy clinical decision making.

Citation Format: Maeve Mullooly, Diana R. Withrow, Rochelle E. Curtis, Shaoqi Fan, Linda M. Liao, Ruth M. Pfeiffer, Amy Berrington de Gonzalez, Gretchen L. Gierach. Association of lifestyle and clinical characteristics with receipt of radiotherapy treatment among women diagnosed with DCIS in the National Institutes of Health-AARP Diet and Health Cohort Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3331.