Drug Combination May Slow Male Breast Cancer Growth

Zeina Nahleh, MD, director of breast oncology in the University of Cincinnati’s (UC) division of hematology and oncology, is leading a national phase-2 clinical trial to test whether the drug anastrozole (Arimidex), currently approved by the Food and Drug Administration (FDA) for treating breast cancer in postmenopausal women, can effectively fight the same disease in men.

“If we’re going to make significant advances against the disease,” says Nahleh, “we need better male-specific treatment strategies.”

Previous research has shown that the female hormone estrogen promotes the growth of certain types of breast cancer. Anastrozole is one of a class of drugs, known as non-steroidal aromatase inhibitors, that block the tumor’s use of estrogen and slow its development.

By treating male breast cancer with a combination of anastrozole and a synthetic hormone called goserelin, Nahleh believes physicians may be able to stop the transition of the male hormone testosterone to the estrogen estradiol, significantly lowering the man’s overall estrogen levels and limiting breast tumor growth.

Goserelin is what is known as a gonadotropin-releasing hormone, which stops testosterone production in men and decreases estradiol in women. It already has FDA approval for the treatment of prostate cancer, endometriosis and advanced premenopausal and perimenopausal breast cancer.

“The biology of breast cancer is different in men and women, so identical treatment methods are not the best solution,” explains Nahleh. “We believe that anastrozole—when used in conjunction with a gonadotropin-releasing hormone injection—will lower the amount of male estrogen in the body, resulting in better control of the breast tumor.”

The trial, sponsored by the National Cancer Institute and Southwest Oncology Group, is the first to test this specific drug combination in men with advanced breast cancer.

“We’ve seen a 26 percent increase in the number of male breast cancer cases since 1973, but the disease is so rare that there’s been little research to determine the best ways to detect and treat the disease specifically in men,” explains Nahleh.

Current male breast cancer treatment methods are based on accepted approaches to the disease in women. Unlike female breast cancer, says Nahleh, the relationship between the estrogen receptor and overall survival in men is uncertain. In addition, mortality from the disease has not declined as it has in women.

Under Nahleh’s direction, researchers from 53 medical centers nationwide will test the drug combination on about 60 male patients—age 18 or older—who have recurrent or advanced breast cancer.

Patients will receive an anastrozole pill every day and a goserelin injection on the first day of 12, month-long cycles. Every two months researchers will collect serum samples to evaluate blood estrogen levels. They will also obtain CAT scan and X-ray images of the tumor to determine how the patient is responding.

After the treatment, Nahleh and her team will follow patients for three years to determine whether the approach is a sustainable option for managing male breast cancer.

The American Cancer Society estimates that more than 1,700 men will be diagnosed with breast cancer in 2006 and about 27 percent will die from the disease.