Side effects of aromatase inhibitors versus tamoxifen: the patients' perspective

Hormonal therapy is a mainstay in the management of estrogen receptor-positive (ER+) breast cancer. Tamoxifen (TAM) has been the drug widely used until the recent emergence of the aromatase inhibitors (AIs). Although AIs appear to be better tolerated than tamoxifen, they do have a different safety profile and these side effects have not been well characterized in community practice. We surveyed patients with ER+ breast cancers who received adjuvant hormonal therapy to determine how these medications impacted their quality of life and whether side effects or cost influenced decisions to continue therapy.

A mailed questionnaire and community cancer registry were used.

Four hundred fifty-two of 902 surveys were returned for a 50% response rate. Eighty-two percent of respondents were placed on (adjuvant hormonal therapy) some form of estrogen-blocking therapy. Fifty-four percent of these were placed on tamoxifen and 46% on an AI. The most troublesome symptoms for tamoxifen and AI users, respectively, included hot flashes (35%/30%), weight gain (14%/15%), insomnia (17%/17%), and joint aches (12%/23%, P = .002). Thirty-nine percent of TAM users and 46% of AI users were taking medications to control their symptoms. Fifty percent of TAM users and 39% of AI users took vitamin E to help control hot flashes. Forty-two percent of TAM users versus 32% of AI users took Advil (Wyeth, Richmond, VA) for muscle/joint aches; 47.5% of AI users switched medication to improve symptoms as compared with only 37% of tamoxifen users (P = .015). The average cost of medications to control side effects for both tamoxifen and AI users was $67.36 per month.

In our survey, both tamoxifen and AI users reported significant and different side effects. AI users suffered more frequently from musculoskeletal complaints, and more AI users switched therapy. Both AI and tamoxifen users used adjunctive medications for symptom control. In both groups, a large number used vitamin E to help hot flashes despite weak evidence to support its effectiveness in this setting. Cost of therapy and symptom control was not a major barrier to care.