Women Show Hesitancy About Tamoxifen, Even if at Increased Breast Cancer Risk

In a multicenter study, only 1 in 5 women at increased risk of breast cancer reported a strong need for tamoxifen preventive therapy, according to a report published Monday.

More than 70% of women in the study, funded by British charity Cancer Research UK, reported strong worries about its long-term effects, and more than half reported concerns about potential unpleasant side effects.

The researchers asked 408 healthy women at a higher risk of breast cancer from 20 centers across England whether they thought they needed to take tamoxifen and their concerns about medication.

The objectives of this study were to:

• Assess whether women at increased risk of breast cancer can be categorized into groups with similar medication beliefs
• Determine whether sociodemographic and clinical variables are related to medication belief group membership
• Examine whether medication belief groups are associated with tamoxifen uptake

The researchers noted that medication beliefs are modifiable determinants of treatment decision making and are influenced by family experiences of cancer and medication use.

One in 5 women (19.4%) reported a strong need for tamoxifen.

Researchers sorted the women into 2 groups about medication beliefs. Both groups held weak beliefs about their need for tamoxifen for current and future health. Group 2 (38%), those with low need but more concerns, reported stronger worries about tamoxifen and medicines in general, and stronger perceived sensitivity to the negative effects of medicines, compared with group 1 (62%), who reported low need and lower concerns.

A subgroup of women accounting for almost two-fifths of the sample reported the strongest medication concerns and perceived sensitivity to medicines.

Uptake of tamoxifen was 14.7%; 3 women were currently taking tamoxifen and 7 women reported having a prescription.

Those in group 1, who had low necessity and lower concerns (18.3%), were more likely to start tamoxifen than those in group 2, who had low necessity and higher concerns (6.4%). However, uptake by women in group 1 was still low. Even for those on tamoxifen, continued uncertainty about personal need might result in lower adherence, which has been shown to be problematic in clinical trials, the researchers said.

After adjusting for demographic and clinical factors, the odds ratio was 3.37 (95% CI, 1.08-10.51; P = .036).

Almost one-third (29%) of the women thought doctors prescribed too many medicines, and more than one-third (35%) thought doctors would prescribe fewer drugs if they had more time. Around a quarter (24%) of the women had experienced bad reactions to medicines in the past.

Almost a quarter (24%) of the women thought people on medication should take regular breaks from the drugs; 23% said they were very sensitive to medicines and 17% believed natural remedies were safer than medicines.

In a follow-up questionnaire, answered by 250 of the women, researchers found that fewer than 15% were taking tamoxifen despite having discussed preventive therapy with a healthcare professional. Women who believed the medication was less necessary and had more concerns about its use were less likely to be taking tamoxifen at follow-up.

The researchers said their study showed how previous treatment expectations can influence primary prevention decision making and emphasizes the need for clinicians to address concerns. They found that medication belief group membership was associated with key indicators of socioeconomic status, which might help identify those who would most benefit from support in making treatment decisions. Understanding those issues may help determine whether preventive therapies can create or exacerbate existing inequalities in breast cancer outcomes.

Reference

Thorneloe RJ, Horne R, Side L, Wolf MS, Smith SG. Beliefs about medication and uptake of preventive therapy in women at increased risk of breast cancer: results from a multicenter prospective study [published online December 3, 2018]. Clin Breast Cancer. doi: 10.1016/j.clbc.2018.10.008.