Study suggests new options for treating breast cancer

Close to half the women in the world diagnosed with breast cancer each year stand to gain from a combined additional treatment begun at the time of breast cancer surgery.

Oophorectomy (removal of both ovaries) plus tamoxifen tablets taken for five years reduce the chance of cancer recurrence by almost 20 percent and increases the likelihood of survival by 11 percent in premenopausal Vietnamese and Chinese women.

Richard R. Love, Medical School professor and medical oncologist at the Comprehensive Cancer Center, presented the study results May 15 at the American Society of Clinical Oncology annual meeting in San Francisco.

Love led the research with co-investigators from seven hospitals – six in Vietnam and one in China. The study enrolled 709 premenopausal patients, all of whom had operable breast cancer. The study took place from 1993-99.

Half the women underwent removal of their ovaries as part of their initial breast cancer treatment and soon after began five years of therapy with tamoxifen. The second group of women received breast cancer surgery (but kept their ovaries) and was not given additional treatment unless cancer returned. Those patients with recurrent breast cancer were offered the choice of oophorectomy plus tamoxifen or tamoxifen alone.

After five years, 73 percent of the first or “adjuvant” group and just more than half (54 percent) of the second group remained free of cancer recurrence.

“The revolution in understanding of the biology of breast cancer is beginning to give real hope for better treatments and longer lives,” Love says.

Analysis of the cancerous tumors removed from the closely related cancer-free survival to the tumors’ measured ability to react with female hormones.

Only those patients whose tumors tested positive for receptors to estrogen (ER) and progesterone (PR) benefited from the adjuvant treatment. Surprisingly, 62 percent of the tissue samples were ER-receptor positive and 62 percent were positive for PR receptors. These findings are similar to those found in American and European breast cancers. Other studies had suggested Asian women were far less likely to develop hormone-sensitive breast cancers.

Bruce E. Hillner of Virginia Commonwealth University analyzed the cost-effectiveness of this adjuvant treatment and found that the cost of gaining a year of life in this setting was $350, an astonishingly low figure.

Because of the major implications for public health policy in countries with limited economic resources, Hillner is further analyzing different treatment strategies based on these study results.

In discussing different standards of care in poorer and richer countries, Love and Nguyen Ba Duc, director of the National Cancer Institute in Hanoi, Vietnam, noted that the risks and benefits of different treatment programs for breast cancer are much different in Vietnam and the United States.

“To date, drug hormone receptor tests on a regular basis are not yet possible in Vietnam,” Duc says. “There has been considerable concern about the increased toxicities associated with chemotherapy in smaller Vietnamese people, and there are no specific data about benefits of adjuvant chemotherapy in Vietnamese women.”

Making available potential new cancer treatments to the majority of patients needing them in poorer countries is a moral requirement and practical necessity, Love adds.

In recent studies of American and European women – who were offered adjuvant treatment at first diagnosis as well as those treated for advanced (metastatic) breast cancer – it appears combined hormonal therapy (oophorectomy and tamoxifen) is more effective than hormonal treatment alone. What’s more, in hormone-receptor positive patients, the combined approach may be better than usual chemotherapy treatments.

But for now, Love stresses the public health impact in the developing world.

“For many poorer women, these study results are very important,” he says. “If this combined hormone treatment was given to 450,000 premenopausal women, mostly in Asia, who now get no (combined) treatment … 50,000 of these young women could be saved each year.”

More information: http://www.cancer.wisc.edu or http://www.ibcrf.org.