Medication Adherence Impacts Breast Cancer Outcomes | ESMO 2024

At the 2024 European Society for Medical Oncology 2024 Congress, researchers presented dozens of posters focused on breast cancer, including the relationship between medication adherence and survival outcomes.

In one poster, researchers found that adjuvant endocrine therapy can improve survival outcomes in women with breast cancer.¹ However, discontinuation of adjuvant endocrine therapy is common, despite a recommendation of 5 years for this treatment.

Researchers identified women diagnosed with nonmetastatic primary breast cancer between 2010 and 2015, aged 50 to 80 years, with positive estrogen receptor (ER+) who underwent surgery.

Medication adherence can impact breast cancer outcomes. | Image credit: JP STUDIO LAB - stock.adobe.com

In total, 6930 patients were identified (median age, 63 years; IQR, 56-70). Within this group, 85% of patients had positive progesterone receptors, and 90% had stage I or stage II cancer. A total of 20.1% of patients did not receive adjuvant endocrine therapy, 52.9% discontinued adjuvant endocrine therapy within 5 years, and 27% were adherent to adjuvant endocrine therapy treatment.

Among those who did not adhere to therapy, 43% received both tamoxifen and aromatase inhibitors, while 29% and 28% received either tamoxifen or aromatase inhibitors, respectively. Compared with the group that did not receive adjuvant endocrine therapy, patients in the adherence and nonadherence group had lower hazard ratios of recurrence-free survival (0.73 and 0.76, respectively), and 0.59 and 0.52 for overall survival, respectively. Results of a multivariate analysis showed improved hazard ratios in the nonadherence group of 0.56 and 0.49 and 0.55 and 0.40 in the adherent group for recurrence-free and overall survival, respectively.

READ MORE: Ribociclib Plus Aromatase Inhibitor Approved As Adjuvant Therapy for HR+/HER2- Early Breast Cancer

In another poster, researchers presented data showing that adherence to oral anticancer medications is significantly affected by metastatic status and side effect severity.²

In a cross-sectional study, 500 individuals with breast cancer were categorized by cancer type (metastatic n=45.6%; nonmetastatic n=54.4%), then measured adherence using the Morisky Medication Adherence Scale (MMAS-8) and the Medication Possession Ratio (MPR).

Overall, medication adherence rates were 46.4% via the MMAS-8 and 71% via the MPR. In the nonmetastatic group, adherence rate was 28.3% via the MMAS-8 and 75.4% via the MPR. Patients with metastatic breast cancer showed a “significantly higher adherence. Additionally, there was a notable inverse correlation between adherence and the severity of adverse effects, such as musculoskeletal pain, neurologic symptoms, fatigue, and hot flashes. Adherence also varied based on treatment duration: shorter treatment periods were associated with better adherence.

Study results highlight “the urgent need for enhanced educational and management strategies tailored to the specific challenges faced by breast cancer patients, especially those dealing with severe [adverse] effects,” the researchers concluded.

READ MORE: Women’s Health Resource Center

References

1. Zuo H, Yan Y, King K, Bigras G, Joseph K. Impact of adjuvant endocrine therapy on survival outcomes in female breast cancer patients over 50. Presented at: European Society of Medical Oncology; September 13-17, 2024; Barcelona, Spain. Abstract 286P.

2. El-Shewy R, Ebid A-HIM, Mobarez MA, et al. Evaluating adherence to oral anticancer medications in metastatic and nonmetastatic breast cancer patients. . Presented at: European Society of Medical Oncology; September 13-17, 2024; Barcelona, Spain. Abstract 376P.