Prior studies have made it clear that racial inequities exist in how metastatic breast cancer (mBC) is diagnosed and treated, leading to lower survival rates among certain groups. These disparities may be driven by comorbidities like hypertension, which affects 60% of patients with breast cancer and is linked to treatment delays and increased mortality in early-stage breast cancer. However, the extent to which blood pressure control influences mortality rates—or contributes to existing racial survival disparities—has not been studied.1
The Bottom Line
- Hypertension is more prevalent among women with mBC, but not much is known about how hypertension or its management may impact survival.
- The new study examined how pharmacologic hypertension management influences all-cause and breast cancer-specific mortality in women with mBC.
- Prioritizing blood pressure control could help to close the survival gap and improve outcomes for Black and Hispanic women with mBC.
Until now, that is. A new longitudinal cohort study published in Cancer Medicine by Haque and colleagues suggests that aggressive hypertension management, particularly an approach that includes multiple therapies, may improve survival outcomes for women with de novo mBC. The findings reveal an opportunity to address mortality disparities by managing common comorbidities concurrently with oncologic treatment.1
“To our knowledge, this is one of the first studies to determine whether pharmacologic management of a common comorbidity—hypertension—is associated with mortality in women with mBC,” the authors remarked.1
Study design and patient demographics
The researchers conducted a retrospective analysis of 1332 women 18 years or older (median age 64, interquartile range 53 to 75 years) who were diagnosed with de novo mBC between 2008 and 2020 within the Kaiser Permanente Southern California health system.1 Patients were divided into 2 groups according to the number of classes of blood pressure medications they were exposed to: monotherapy (1 class) or polytherapy (2 or more classes, including single-pill combinations).
The women in the monotherapy group were reassessed every 6 months. They remained in this category throughout the study unless they filled a prescription for a medication from a different drug class.
At the time of their mBC diagnosis, nearly half (48.4%) of the cohort had a documented diagnosis of hypertension. This prevalence was highest among Black women, affecting 64.6%. Among Hispanic women, 46.1% were diagnosed with hypertension. During the follow-up period, which lasted as long as 13.9 years, 52.9% (n=704) of the total cohort received anti-hypertensive treatment: 20.4% were managed with monotherapy, while 32.5% received polytherapy.
Polytherapy is associated with improved survival
Patients with mBC were followed through 2021 to assess the impact of anti-hypertensive medication use on all-cause and breast cancer-specific mortality.
Among patients receiving blood pressure treatment, 73.2% (n=515) passed away during the study period, with most of those deaths resulting directly from breast cancer (n=444). The study found that patients receiving polytherapy had lower all-cause mortality rates compared to those on monotherapy (21.4 versus 28.5 per 100 person-years, respectively).
Polytherapy reduced all-cause and breast cancer-specific mortality more effectively than monotherapy across all racial groups, with the greatest drop in all-cause mortality (35.7%) observed among Black women.
In multivariable Cox regression models adjusted for age, race/ethnicity, and breast cancer subtype, polytherapy was associated with a 38% reduction in the risk of all-cause mortality (adjusted hazard ratio [HR] 0.62, 95% confidence interval [CI] 0.47 to 0.82) when compared to monotherapy. This survival benefit was most pronounced among Hispanic patients, who had a 60% reduction in mortality risk (HR 0.40, 95% CI 0.20 to 0.84). A similar trend was indicated in Black patients but was not statistically significant.
Adherence to therapy is a key aspect, too
Adherence to anti-hypertensives was measured using the medication possession ratio (MPR). According to the authors of the current study, an MPR of 80% or higher is indicative of consistent, continuous drug use.
Medication adherence emerged as a primary driver of survival benefits. Patients with high adherence to their anti-hypertensive regimens experienced a 58% (adjusted HR 0.42, 95% CI 0.24 to 0.76) reduction in all-cause mortality and a 57% (adjusted HR 0.43, 95% CI 0.24 to 0.77) reduction in breast cancer mortality if on polytherapy compared to monotherapy.
Overall, polytherapy was more effective at helping patients hit certain clinical targets. An analysis of 482 hypertensive patients showed that polytherapy (75.1%) was more effective than monotherapy (24.9%) at achieving systolic blood pressure under 140 mm Hg. Polytherapy users had a 36% lower likelihood of uncontrolled hypertension (odds ratio [OR] 0.64, 95% CI 0.42 to 0.97). Additionally, more than 80% of patients who received beta-blockers, which may offer anti-tumor benefits, were in the polytherapy group.
Where the study fell short
This study included a diverse cohort, with approximately 50% patients of color and zero loss to follow-up. By using pharmacy databases rather than self-reports, the researchers ensured accurate medication tracking while adjusting for extensive covariates, including lifestyle factors, healthcare utilization, and specific cancer therapy. Nonetheless, the authors noted several limitations to the study’s design:
- The cohort consisted of patients within an integrated healthcare system, which may limit generalizability of the findings to uninsured populations or those with fragmented care.
- While the researchers adjusted for multiple variables, potential confounding from unmeasured lifestyle behaviors and biological factors, or from the specific clinical motivations behind patients receiving surgery, were not fully captured.
- Follow-up ended in December 2021, which precludes assessing the effectiveness of newer targeted therapies.
- The study focused on de novo mBC, and results may differ for patients with recurrent metastatic disease.
Clinical implications and recommendations
The intersection of oncology and cardiology is becoming increasingly relevant as cancer treatments extend the lives of patients with metastatic disease. As Haque and colleagues noted, “In this diverse cohort of women with de novo mBC, hypertension was the most common comorbidity and highest in Black women. All-cause mortality risk was lower among those treated with polytherapy versus monotherapy for hypertension, with the greatest statistically significant attenuation seen among Hispanic patients but also mitigated in Black patients.”1
The investigators suggest that awareness of comorbidities like hypertension is a key, nonclinical factor in reducing mortality and addressing racial/ethnic survival disparities among women with de novo mBC. Polytherapy may offer benefits beyond simple blood pressure reduction, potentially mitigating physiological stress and systemic inflammation that could otherwise accelerate mBC progression, especially among Black and Hispanic women.
For physicians treating mBC, these data underscore the importance of rigorous comorbidity management. Prioritizing hypertension control through polytherapy and supporting medication adherence may serve as a critical strategy to extend survival and reduce racial and ethnic disparities in breast cancer outcomes.
Published: May 28, 2026
As a science educator and medical writer, Elethia W. Tillman has a passion for translating complex medical concepts into impactful, accurate, and engaging communications that empower informed decision-making, advance scientific understanding, and drive positive healthcare outcomes.
