Accepted for/Published in: JMIR Research Protocols
Date Submitted: Feb 7, 2020
Date Accepted: Oct 20, 2020
Date Submitted to PubMed: Oct 22, 2020
(closed for review but you can still tweet)
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
The Effects of Radiotherapy and Comorbidity on Health-Related Quality Of Life and Mortality among Older Women with Low-Risk Breast Cancer: Proposal For a Retrospective Longitudinal Study
ABSTRACT
Background:
The National Comprehensive Cancer Network Breast Cancer Guidelines Committee has suggested that the omission of adjuvant radiation therapy (RT) after breast-conserving surgery can be a reasonable option among older women with low-risk breast cancer (early-stage, ER-positive, and node-negative) if they are treated with endocrine therapy. However, RT usage in this group of women still exceeds 50%. On the other hand, older women tend to forego RT (even when necessary) due to cost, inconvenience, and potential adverse responses associated with RT. Understanding health-related quality of life (HRQOL) change with receipt of RT among older women in the modern era is limited due to the underrepresentation of this population in clinical trials.
Objective:
The proposed study aims to examine the associations of RT with HRQOL trajectories as well as survival outcomes among older women over 5-10 year follow-up. We will also assess whether pre-diagnosis comorbidity burden influences receipt of RT and whether the associations between RT and HRQOL trajectory and survival outcomes are modified by comorbidity burden.
Methods:
We will use a retrospective cohort study design with the population-based database of Surveillance, Epidemiology, and End-Results linked to the Medicare Health Outcomes Survey (SEER-MHOS). Older women (65+) diagnosed with low-risk breast cancer in 1998-2014, received BCS, and participated in MHOS 1998-2016 are eligible for the current analysis. The clustering method, latent class analysis, will be used to identify each patient’s pre-diagnosis comorbidity burden, and HRQOL will be evaluated using SF-36/VR-12 scales. The inverse-weighted estimates of the probability of treatment will be included as a covariate to control for treatment selection bias and confounding effects in subsequent analysis. The association of RT with HRQOL trajectory will be evaluated using inverse-weighted semiparametric B-splines models. The inverse-weighted Cox regression model will be used to obtain hazard ratios with 95% confidence intervals for the association of RT with survival outcomes. Differential effects of RT on both outcomes according to comorbidity burden class will also be evaluated.
Results:
As of January 2020, the study was approved by the institutional review board, and the SEER-MHOS data was obtained from the National Cancer Institute and SEER. Women with low-risk breast cancer who met inclusion and exclusion criteria have been identified, and pre-diagnosis comorbidity burden has been characterized using latent class analysis. Further data analysis will begin in February 2020, and the first manuscript will be submitted in a peer-reviewed journal in June 2020.
Conclusions:
This research has the potential to improve clinical outcomes of older women with low-risk breast cancer by providing them additional information on the HRQOL trajectories when they make RT treatment-decision. It will facilitate informed, shared treatment decision and cancer care planning and ultimately will improve the HRQOL of older women with breast cancer. Clinical Trial: NA
Citation
