Cancer outcomes and cardiopulmonary toxicities for Black patients with breast cancer treated with proton therapy.

Abstract

Background: Black women have a 40% higher breast cancer mortality rate than White women and are at a higher risk of acquiring cardiovascular disease. Proton therapy can be used to mitigate cardiac radiation exposure; however, proton therapy remains a scarce resource in the United States. We report on the cardiovascular profiles of patients undergoing proton therapy to determine the potential benefit of the therapy for Black women compared with patients of other races.

Methods: We retrospectively analyzed 599 patients with breast cancer who received proton therapy from June 2016 to December 2021 at the Maryland Proton Treatment Center. A variety of sociodemographic, disease, and treatment variables were analyzed using descriptive statistics.

Results: With a median follow-up of 26 months (range = 0.47-90 months), Black patients made up 31.6% of the population and presented with higher rates of hypertension (P < .001), cardiopulmonary conditions (P < .001), and a higher median body mass index (P = .015) compared with the other cohort, a trend that persisted at the time of post-proton therapy follow-up. Black women had higher rates of triple-negative disease (P < .001), with subsequent greater receipt of neoadjuvant chemotherapy (P = .039). Pulmonary events were 2.6 times more likely to occur in Black patients than in the non-Black cohort after proton therapy (odds ratio = 2.60, 95% CI = 1.39 to 4.88; P = .003).

Conclusions: Black women presenting for proton therapy had higher baseline risks of cardiovascular co-morbidities combined with more aggressive breast cancer biology and a subsequent 2.6-fold increased risk of pulmonary events after proton therapy. Our findings support the use of advanced radiation techniques as a means of sparing important organs at risk, especially in historically marginalized populations.