Clues to Why Breast Cancer More Fatal in Blacks Thu Feb 7, By Faith Reidenbach NEW YORK (Reuters Health) Since the mid-1990s, it's been known that African-American women's high breast cancer death rate--which is triple the rate in other ethnic groups--is partly due to biological differences in how fast breast tumors grow. Now, researchers at Howard University have uncovered a clue to why tumor cell growth and spread is so aggressive in African-American women, and what might be done about it. The difference between African-American women and those in other ethnic groups lies in the composition of estrogen receptors, according to a team led by Dr. Indra Poola, a biochemist and molecular biologist at the Washington, DC university. Estrogen receptors are proteins on cell surfaces that bind to the estrogen in a woman's body. All normal breast cells have estrogen receptors, and in some cases cancer cells have them too. If they do, estrogen will feed the growth of the tumor. Tamoxifen is given to some women with breast cancer to block the interaction between estrogen and estrogen receptors, thus shrinking the tumor. Four subtypes of receptors, called isoforms, are known to be active in regulating the amount of estrogen that reaches a cell. Scientists are beginning to think that the growth of a breast tumor may depend in part on which of these isoforms are present on a cell, and in what quantity. "In normal tissue, let's say there are 100 copies of one isoform and 200 copies of another and 300 copies of another, so there is a balance for normal function," Poola explained during an interview with Reuters Health. "In cancer, this balance is changed." In breast tumor samples from 24 African-American women, Poola and her colleagues observed that the number of copies of one particular isoform was significantly lower than in normal tissue from the same patients. That isoform, called the beta-estrogen receptor, is thought to have a protective effect against cancer development if it is present in normal amounts. Tumor samples also had a significantly greater number of copies of two other isoforms, compared with normal tissue. Increases in the quantities of these isoforms may contribute to the aggressive proliferation of cancer cells in African-American women, the researchers speculate in the February 15th issue of the journal Cancer. In this study, the research team did not examine tumor samples from white women, but Poola told Reuters Health, "Based on my research experience, my results on unpublished Caucasian patients, the composition of isoforms seems different in African-American tumors." The research findings "could have a lot of implications for drug therapy," Poola continued. She suggests that "in addition to treating African-American patients with tamoxifen, maybe we should also (develop drugs that will) block these two other isoforms, which have gone up in the tumors in African-American women." SOURCE: Cancer 2002;94:615-623. Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.