Cardiotoxicity among socioeconomically marginalized breast cancer patients.

PURPOSE: Evidence of cardiotoxicity risk related to anthracycline or trastuzumab exposure is largely derived from breast cancer cohorts that under-represent socioeconomically marginalized women, who may be at increased risk of cardiotoxicity because of high prevalence of cardiovascular disease risk factors. Therefore, we aimed to estimate cardiotoxicity risk among socioeconomically marginalized breast cancer patients treated with anthracyclines or trastuzumab and describe clinical consequences of cardiotoxicity. METHODS: We linked electronic health records with institutional registry data from a Comprehensive Community Cancer Program within a safety-net health system. Eligible patients were adult females, diagnosed with first primary invasive breast cancer between 2013 and 2017, and initiated anthracyclines or trastuzumab as part of first-line therapy. We estimated cumulative incidence (risk) of cardiotoxicity with corresponding 95% confidence limits (CL) using the Aalen-Johansen estimator with death as competing risk. RESULTS: Our study population comprised 169 women with breast cancer (103 initiated anthracyclines and 66 initiated trastuzumab). Cumulative incidence of cardiotoxicity was 21% (95% CL: 12%, 32%) at one year and 25% (95% CL: 15%, 35%) at three years among women who initiated trastuzumab, whereas cumulative incidence was 3.9% (95% CL: 1.3%, 8.9%) at one year and 5.9% (95% CL: 2.4%, 12%) at three years among women who initiated anthracyclines. More than half of patients with cardiotoxicity experienced interruption of cancer treatment. CONCLUSION: Our findings suggest high risk of cardiotoxicity among socioeconomically marginalized breast cancer patients after initiation of anthracyclines or trastuzumab. Strategies are needed for optimizing cancer treatment effectiveness while minimizing cardiotoxicity in this population.

Impact of prognostic factor distributions on mortality disparities for socioeconomically disadvantaged cancer patients.

PURPOSE: We aimed to assess whether differences in the distributions of prognostic factors explain reported mortality disparities between urban safety-net and Surveillance, Epidemiology, and End Results (SEER) cancer populations. METHODS: We used data from SEER and a safety-net cancer center in Texas. Eligible patients were adults aged ≤64 years and diagnosed with first primary female breast, colorectal, or lung cancer between 2008 and 2016. We estimated crude and adjusted risk differences (RD) in 3- and 5-year all-cause mortality (1- and 3-year for lung cancer), where adjustment was based on entropy balancing weights that standardized the distribution of sociodemographic and tumor characteristics between the two populations. RESULTS: Our study populations comprised 1914 safety-net patients and 389,709 SEER patients. For breast cancer, the crude 3- and 5-year mortality RDs between safety-net and SEER populations were 7.7% (95% confidence limits [CL]: 4.3%, 11%) and 11% (95% CL: 6.7%, 16%). Adjustment for measured prognostic factors reduced the mortality RDs (3-year adjusted RD = 0.049%, 95% CL: -2.6%, 2.6%; 5-year adjusted RD = 5.6%, 95% CL: -0.83%, 12%). We observed similar patterns for colorectal and lung cancer albeit less magnitude. CONCLUSIONS: Sociodemographic and tumor characteristics may largely explain early mortality disparities between safety-net and SEER populations but not late mortality disparities.