Breast Cancer Drugs' Side Effects May Depend on Patient's Age

By Jane Farrell

Two leading breast cancer drugs cause different symptoms depending on the age of the woman who is taking the drug, researchers say.

The findings could be an important step toward personalized medicine for women with breast cancer, said Dr. Patricia Ganz, director of the UCLA Jonsson Comprehensive Cancer Center’s Prevention and Control Research program and the study’s first author.

The study examined data for 1,193 postmenopausal women with a type of breast cancer called ductal carcinoma in-situ. The women had undergone lumpectomy and radiotherapy and were enrolled in a phase 3 clinical trial evaluating the drugs anastrozole and tamoxifen. The clinical trial confirmed that both drugs were safe.

Ganz and her team assessed factors influencing the women’s quality-of-life as well as specific physical symptoms, such as hot flashes, vaginal dryness, and muscle and joint pain. The drugs tended to affect women differently, Ganz said: Those taking tamoxifen generally had more severe hot flashes, and those taking anastrozole reported more sever vaginal dryness and muscle and joint pains.

The researchers then compared the results for women who were 60 and older with those who were under 60 years old. Women in the younger group were more likely to have hot flashes, weight problems, vaginal symptoms and gynecological symptoms than those in the older group. Symptoms such as depression and fatigue affected women in both age groups similarly, and did not worsen while they were taking the drugs.

The study was published online by the journal The Lancet.

The scientists analyzed data from before the trial, during the five years of treatment and 12 months after.

The phase 3 clinical trial, from which the UCLA researchers drew the data for their study, was conducted to determine whether anastrozole was superior to tamoxifen. Ganz also is a co-author of that research, which also was published today by The Lancet.

“Both of these drugs are excellent and can reduce the risk for breast cancer recurrence,” Ganz said. “Physicians and patients need to use this information along with the main trial outcomes to choose the optimal treatment for each woman.”

The research was supported by the National Cancer Institute and AstraZeneca, which markets anastrozole under the brand name Armidex and tamoxifen under the brand name Nolvadex.