Source: Graefes Arch Clin Exp Ophthalmol  |  Posted 6 years ago

By Ed Susman

HOLLYWOOD, FL -- March 18, 2005 -- The tamoxifen era is over.

The newest breast cancer guidelines of the National Comprehensive Cancer Network suggest that for adjuvant hormonal therapy for postmenopausal women, the use of aromatase inhibition is preferred as a long-term prevention strategy over tamoxifen as a single agent.

"Tamoxifen is a terrific drug," said Robert Carlson, MD, professor of medicine, Stanford University Medical School, Stanford, California, United States, "but recent clinical trials have shown that the aromatase inhibitors improve disease-free survival.

"Tamoxifen alone in postmenopausal women has fallen off the radar screen," he said here March 16[^]th[] at the NCCN's 10[^]th[] Annual Conference on Clinical Practice Guidelines and Data Outcomes Research.

The changes in guidelines was based on several clinical trials that established the role of the aromatase inhibitors in preventing recurrence of cancer in the adjuvant setting: ATAC (Anastrozole, Tamoxifen, Alone or in Combination); and MA-17, which showed a benefits with letrozole; and Intergroup Exemestane Study, Dr. Carlson said.

According to the new guidelines for adjuvant hormonal therapy, premenopausal women are treated with tamoxifen for 2 to 3 years with or without ovarian supplementation or ablation. If they remain premenopausal after the first round of treatment they complete 5 years of tamoxifen. If at that point they are postmenopausal they receive letrozole for 5 year. If they are still premenopausal no further treatment is performed.

Women who are postmenopausal at the start of adjuvant therapy are treated with anastrozole for 5 years, or tamoxifen for 2 to 3 years, followed by exemestane or anastrozole to complete a 5-year adjuvant hormonal therapy course, or tamoxifen for 4.5 to 6 years, and then by letrozole for 5 years.

"The panel believes the three selective aromatase inhibitors -- anastrozole, letrozole and exemestane -- have similar anti-tumor efficacy and similar toxicity profiles," Dr. Carlson said. Physicians should try to judge how well their patient fits into the criteria and scenario of the various clinical trials and treat them with drugs that best fit that situation, he said.

The lack of an overall survival benefit seen with the aromatase inhibitors may be partly due to the effectiveness of tamoxifen in treatment of patients; competing causes of death as the women in the studies age, or the fact that separation of the curves that express differences in mortality might do not occur until several years following treatment -- much the way the mortality benefit with tamoxifen did not become apparent until long-term results were examined.

[Presentation title: Update: Breast Cancer Guidelines.]