TOPLINE

Bisphosphonate (BP) use for at least 1 year after breast cancer diagnosis was associated with reduced all-cause mortality and breast cancer-specific mortality in women with hormone receptor-positive (HR+) breast cancer. Among those with triple-negative breast cancer (TNBC), pre-diagnostic BP use and continued use across both pre- and post-diagnosis periods, on the other hand, were linked to more than tripled recurrence risk and more than doubled breast cancer-specific mortality risk, the new study showed.

METHODOLOGY

• A meta-analysis published in 2015 reported beneficial effects of BPs on breast cancer recurrence, distant recurrence, and mortality, with larger magnitude effects observed among postmenopausal women. According to the authors of the new population-based cohort study, limited data are available on the impact of pre-diagnostic BP use on patient outcomes, and studies on the efficacy of BP therapy across patients with different breast cancer subtypes are limited.
• The new study was conducted using data from the Surveillance, Epidemiology and End Results cancer registries in Albuquerque, New Mexico, and Seattle, Washington, enrolling 3696 women (2260 HR+ cases and 1436 TNBC cases) aged 20-69 years diagnosed with primary invasive breast cancer between June 2004 and June 2015. Participants were assessed for BP use within 2 years before diagnosis and during post-diagnosis follow-up through medical record abstraction and structured telephone interviews, with detailed information on medication name, start date, and end date for each episode of use.
• Primary outcomes included recurrence, any second breast cancer event, all-cause mortality, and breast cancer-specific mortality. The median follow-up time to death was 168.3 months for HR+ cases and 147 months for TNBC cases.
• Analysis employed multivariable-adjusted Cox proportional hazards models, treating BP use as time-fixed for pre-diagnostic period and time-varying for post-diagnosis period, with adjustments for age, BMI, osteopenia/osteoporosis history, cancer stage, race and ethnicity, smoking, alcohol use, surgery, radiation, chemotherapy, and adjuvant endocrine therapy for HR+ patients.
• A 6-month landmark analysis was implemented for recurrence and second breast cancer event outcomes to exclude patients who experienced first event or were censored within 6 months after diagnosis.

TAKEAWAY

• Among HR+ breast cancer patients, post-diagnostic BP use for at least 12 months was associated with reduced all-cause mortality (hazard ratio [HR], 0.67) and breast cancer-specific mortality (HR, 0.54) compared to never users.
• For HR+ cases who initiated BP use only after diagnosis, breast cancer-specific mortality was significantly reduced (HR, 0.62), with lower point estimates also observed for recurrence and any second breast cancer event, though not reaching statistical significance.
• Among TNBC patients, pre-diagnostic BP use was associated with increased risks for recurrence (HR, 2.94), any second breast cancer event (HR, 2.72), and breast cancer-specific mortality (HR, 2.39).
• Patients with TNBC who continued BP use across both pre- and post-diagnosis periods showed elevated risks for recurrence (HR, 3.43), any second breast cancer event (HR, 3.20), and breast cancer-specific mortality (HR, 2.54).

IN PRACTICE

“Although this study confirmed the protective effects of post-diagnostic BP use on risks of mortality among HR+ cases, further studies are required to prove the effects of post-diagnostic BP use among TNBC participants,” the authors of the study wrote.

SOURCE

This study was led by Liuye Huang, MHS, and Christopher I. Li, MD, PhD, both at Fred Hutchinson Cancer Center in Seattle, Washington. It was published online in Cancer.

LIMITATIONS

This study was unable to report results specific to HR-negative/human epidermal growth factor receptor 2-positive breast cancer cases due to limited sample size of these cases. Researchers could not track surgery, radiation, and chemotherapy treatment for subsequent breast cancer events or other cancers after initial breast cancer diagnosis, which may have minimal residual confounding for mortality-related models. Given the limited number of patients prescribed BPs, investigators were unable to conduct clinically meaningful subgroup analyses such as oral vs intravenous formats of BP use, the purpose of BP prescription, and specific metastatic sites. According to the authors, the positive association between continuing BP use and various clinical outcomes among TNBC cases could be largely explained by underlying host factors carried over from patients who initiated BP before diagnosis.

DISCLOSURES

This study received support from the Breast Cancer Research Foundation (BCRF-24-193) and the National Cancer Institute (261201000029C and P50 CA148143). Ulrike Peters, PhD, disclosed receiving consulting fees from AbbVie and individual stocks in multiple companies including Amazon, Boeing Company, BioNTech, BYD Company Limited, Crowdstrike Holdings Inc, CureVac, Alphabet Inc Class C, Microsoft Corp, MicroStrategy Inc, NVIDIA Corp, and Stellantis held by family members. The remaining authors reported no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.