Age Affects Breast Cancer Patients' Reaction to 2 Drugs

How well postmenopausal patients tolerate tamoxifen and anastrozole for one type of breast cancer varies with age.

A new study of postmenopausal women with hormone-positive ductal carcinoma in-situ who underwent lumpectomy and radiotherapy found that their symptoms, and symptom severity, while taking both tamoxifen and anastrozole tend to vary based on the patient’s age. The study was published in The Lancet and presented at the San Antonio Breast Cancer Symposium.

Patricia Ganz, MD, director of the University of California, Los Angeles, Jonsson Comprehensive Cancer Center’s Prevention and Control Research program, and her team examined data from 1193 women enrolled in a phase 3 trial evaluating the 2 drugs. The investigators analyzed data from before the trial, during the 5 years of treatment, and 12 months afterwards.

“Both of these drugs are excellent and can reduce the risk for breast cancer recurrence,” Dr Ganz said.

However, the drugs tended to affect women differently. A total of 601 women were assigned to tamoxifen and 592 were assigned to anastrozole.

The study looked at factors influencing the women’s quality of life as well as specific physical symptoms, such as vasomotor symptoms, vaginal dryness, and muscle and joint pain. The women taking tamoxifen generally had more severe hot flashes, and those taking anastrozole reported more severe vaginal dryness and muscle and joint pains.

The researchers compared the results for women who were in the 60-and- older age group with those who were younger than 60 years of age. Women in the younger age group were more likely to have hot flashes, vaginal and gynecologic symptoms, and weight problems than the women in the over-60 age group. Sexual functioning did not differ significantly between the 2 age groups. Both age groups reported depression and fatigue in similar degrees, which did not worse while taking the drugs.

The researchers conclude that given the similar efficacy of tamoxifen and anastrozole for women older than age 60, decisions about treatment should be informed by the risk for serious adverse health effects and the symptoms associated with each drug. For women younger than 60 years old, treatment decisions might be driven by efficacy (favoring anastrozole); however, if the side effects of anastrozole are intolerable, switching to tamoxifen is a good alternative.

The research was supported by AstraZeneca, which markets the 2 drugs, and the National Cancer Institute.