Most Women at High Risk Reject Breast Cancer Chemoprevention Drugs

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A recent study has found that the majority of women at an increased risk of developing breast cancer either refuse or do not adhere to preventive treatment.

A research team led by Sam Smith, BSc, MSc, PhD, Wolfson Institute of Preventive Medicine, Queen Mary University of London, Cancer Research UK, collected data from 26 international studies, including 21,423 women at high risk of breast cancer.

The study, which was recently published in Annals of Oncology, found that only 16.3% of women took the preventive medication (95% CI, 13.6-19.0).

“Our important research reveals that only a small portion of eligible women make the decision to have preventative medication,” Smith said in a statement. “It’s crucial to find out why so many chose not to take the drugs—or stopped taking them before completing the course.”

The investigators used PubMed, CINAHL, EMBASE, and PsychInfo to analyze women who were offered the preventive therapies either through a clinical trial or in a non-trial setting.

More than 25% of those enrolled in clinical trials chose to take the medication (95% CI, 18.3-32.2, P <.001), compared with only approximately 9% outside of a trial (95% CI, 6.8-10.9, P <.001).

The researchers also looked at 18 studies to evaluate women’s adherence to preventive drugs, including the chemopreventive agents tamoxifen and raloxifene, either through a clinical trial or referral by a physician.

The investigation found that most studies reported more than 80% of the women adhering over the first year. However, those numbers declined over the following 5 years, with only one study reporting a persistence of at least 80% by 5 years.

“We need to find out more about how women at higher risk of breast cancer make decisions about the different ways they can reduce the risk of developing the disease, to make sure that they have the information they need to make the choice that is right for them,” Martin Ledwick, head cancer information nurse, Cancer Research, UK, said in a statement.

While the authors concluded that further research is needed to determine why women are rejecting preventive drugs, the study found that higher uptake was significantly associated with an abnormal biopsy, physician recommendation, higher objective risk, fewer concerns about adverse events, and older age.

Lower adherence was associated with being prescribed tamoxifen over a placebo or raloxifene, depression, smoking, and older age.

Trish Jamieson, 62, was considered to be at high risk of breast cancer after two close relatives developed the disease at a young age, and she lost her sister at age 38.

Jamieson enrolled in the IBIS II trial where she took anastrozole until March 2011.

Results of the recent phase III NSABP B-35 trial show that overall quality of life is similar among patients taking tamoxifen or anastrozole, but adverse events can include hot flashes, night sweats, vaginal dryness, and joint pain.

“It’s not for everyone but I weighed up the pros and cons—which can include side effects&mdash;and decided it was something that I wanted to do,” Jamieson said in a statement. “It’s definitely a personal choice but I was glad to have been given this option.”

Smith SG, Sestak I, Forster A, et al. Factors affecting uptake and adherence to breast cancer chemoprevention: A systematic review and meta-analysis. Ann Oncol. [published online December 8, 2015] pii: mdv590.