Two Drugs Equal for Early Breast Cancer

According to a recent study was carried out at 333 hospitals in North America, Postmenopausal women with hormone-positive ductal carcinoma in situ treated by lumpectomy with clear resection margins and whole breast irradiation were randomly assigned to receive either tamoxifen (20 mg/day), or anastrazole (1 mg/day) for 5 years, stratified by age (<60 years vs ≥60 years).

Patients and investigators were masked to treatment allocation. Patients were asked to fill questionnaires at baseline, and every 6 months thereafter for 6 years. The primary outcomes were SF-12 physical and mental health component scale scores, and vasomotor symptoms (as per the BCPT symptom scale). Secondary outcomes were vaginal symptoms and sexual functioning. Exploratory outcomes were musculoskeletal pain, bladder symptoms, gynecological symptoms, cognitive symptoms, weight problems, vitality, and depression.

Between Jan 6, 2003, and June 15, 2006, 3104 patients were enrolled in the study, of whom 1193 were included in the quality-of-life sub study: 601 assigned to tamoxifen and 592 assigned to anastrazole. It was interpreted that 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, then switching to tamoxifen is a good alternative.

Jack Cuzick, director of the Wolfson Institute of Preventive Medicine at Queen Mary University of London, England and his team analyzed nearly 3,000 women, all past menopause, who had hormone-receptor positive ductal carcinoma in situ (DCIS) breast cancer and underwent surgery to excise it. With DCIS, the cells that line the milk ducts have changed but not spread into the surrounding breast tissue.

The objective of the study was to examine breast cancer recurrence, and to study whether it was more likely with one drug than the other.The researchers said that aromatase inhibitors such as anastrazole have been shown in other studies to be better than tamoxifen in postmenopausal women who have invasive cancers. The less-researched area, Cuzick explained, is DCIS.

“Our results show anastrozole to be slightly better, but it was not significant,” he said. However, the side effect profiles were slightly better with anastrozole, he added. “Tamoxifen has [potential] blood clot problems, and those don’t occur with anastrozole,” Cuzick said.

And while those on anastrozole reported more aches and pains, those on tamoxifen were more likely to have hot flashes. According to the findings, tamoxifen blocks estrogen receptors in the breast cells to hamper cancer growth. Anastrozole stops estrogen production in fat tissue, which makes small amounts of hormone.

The results of the new DCIS research “are exactly what we see in invasive breast cancer,” said Dr. Joanne Mortimer, director of the Women’s Cancer Programs and co-director of the Breast Cancer Program at the City of Hope Comprehensive Cancer Center, in Duarte, Calif. DCIS has been in the news recently, she said, “because it is not an invasive cancer, yet is treated as aggressively.”

Many have challenged the need to even treat DCIS, Mortimer said, suggesting doctors wait until invasive cancers develop. The new findings suggest that approach is not warranted, she added.”The fact that DCIS and invasive cancer both respond to endocrine therapy [tamoxifen and anastrozole] suggests that we should treat DCIS, so that invasive cancers don’t develop,” she said.