Women at Risk for Breast Cancer Don't Take Preventive Drugs

Liam Davenport

December 08, 2015

More than four fifths of women who are at high risk of developing breast cancer choose not to take drugs that could prevent the disease, according to a meta-analysis by researchers from the United Kingdom (UK).

The meta-analysis, published online December 8 in the Annals of Oncology, included 26 studies of chemoprevention uptake in 21,423 women. The pooled uptake estimate was 16.3% (range, 0% to 54.9%).

"Our important research reveals that only a small proportion of eligible women make the decision to have preventative medication," lead author Sam Smith, PhD, CPsychol, Cancer Research UK postdoctoral fellow, Centre for Cancer Prevention, Queen Mary University of London, UK, 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."

In an interview with Medscape Medical News, Dr Smith said that it is important that women are informed about the option of chemoprevention. "I have no problem with low uptake, as long as women are making educated decisions about it," he said.

Martin Ledwick, head cancer information nurse at the charity Cancer Research UK, which provided funding for the study, added: "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."

Study Details

The team searched PubMed, CINAHL, Embase, and PsychINFO, identifying 3851 articles that reported uptake and adherence to therapeutic agents to prevent breast cancer among high-risk women.

After eligibility analysis, which included a quality assessment using the Mixed Methods Appraisal Tool, 24 papers reporting on 26 studies and involving 21,423 women were selected for meta-analysis.

This gave a pooled estimate for update of preventive medications for women at high risk for breast cancer of 16.3%, although there was a high degree of heterogeneity between the studies (P < .001).

Although study location or the agent in question did not affect rates of uptake, rates were significantly higher among women enrolled in clinical trials vs those in nontrial settings, at 25.2% vs 8.7% (P < .001).

Factors associated with uptake identified in the studies assessed included an abnormal biopsy finding, a physician recommendation, higher objective risk for breast cancer, fewer adverse effect or trial concerns, and older age. Lower uptake was associated with concerns about concerns over contraindications with estrogen.

Adherence was assessed in 18 separate studies that met the inclusion criteria. Among women who started preventive medications, adherence was high, at more than 80% in studies reporting 2-year follow-up. In studies reporting 5-year follow-up data, adherence ranged from 61.1% to 80.8%. However, other studies reported sharp declines in adherence after 6 months of treatment.

Lower adherence was associated with allocation to tamoxifen as opposed to placebo or raloxifene, depression, smoking, and older age. All the qualitative studies reported discussing the risk for breast cancer.

Dr Smith commented to Medscape Medical News that the issue of drug adverse effects was important in determining whether patients take up medications to prevent breast cancer.

He told Medscape Medical News, "People making decisions about breast cancer factor in the concerns they have (eg, side effects, addiction, et cetera) and compare this with how necessary they believe the medications to be (eg, how threatening the condition is, how good the medications are)."

"We also noted that the quality of side-effect reporting in this area was relatively poor and should be improved if we are to fully understand the role of side effects in decision-making in this context."

One important aspect is that of how empowered women feel to ask about preventive medications. However, Dr Smith believes that feeling confident about asking questions is not the patient's responsibility.

He said, "I would probably argue that patient empowerment does not and should not come from the patients themselves."

"If patients do not come fully prepared and empowered then that is okay, and it is the clinician's responsibility to adequately convey the information that will facilitate informed decision-making."

He added: "Patient empowerment can come about from good-quality communication initiated by their provider."

In this regard, women may also benefit from counseling, although it may not be enough, in itself, to increase uptake of preventive medications.

Noting that women at risk for breast cancer in the UK are eligible to attend yearly clinics to discuss their risk, along with the possibility of chemoprevention, Dr Smith said: "It gives an opportunity to discuss concerns, but also provides a prompt to start thinking about it as a possibility. However, uptake is still low in these clinics."

He continued: "We must remember, however, that the goal here is not simply to increase uptake. It is to increase informed decisions about the topic, which may or may not influence decisions to take the medication."

Another aspect highlighted by the study is the difference in uptake between women enrolled in clinical trials and those attending routine clinic appointments. "This strongly suggests to me that there are difficulties with implementing preventive therapy in routine care after policy recommendations have been made," Dr Smith noted.

"Efforts should be made to address this by ensuring clinicians are adequately informed to have these discussions with patients," he added.

Dr Smith is supported by a Cancer Research UK Postdoctoral Fellowship. Other authors are supported by a Cancer Research UK – BUPA Cancer Prevention Postdoctoral Fellowship and by the National Institute for Health Research Collaboration for Leadership in Applied Research and Care (C LAHRC) North Thames. The authors have disclosed no relevant financial relationships.

Ann Oncol. Published online December 8, 2015. Abstract

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