Miami Herald - University of Miami medical researchers say they are close to solving a medical mystery: why Bahamian women tend to get breast cancer earlier in life, and in a more aggressive form, than other women. The breakthrough is a step toward new screening tests that could identify those at risk.

''We believe strongly we have found some bad genes in the Bahamas,'' says Dr. Judith Hurley, a UM breast-cancer specialist and lead author of the Bahamas study. ``And in such isolated island populations, the genes are passed on. They go round and round within extended families on small islands and stay in the population.''

The researchers have looked at 18 Bahamian families living in South Florida, and are launching a wider study, seeking 200 volunteers with breast cancer in Freeport, Nassau and the Out Islands.

The early study already is providing valuable information. Corlette Floyd, a Bahamian woman living in South Florida, learned she had the mutant gene. And while she died of breast cancer earlier this year, her daughter, Kimberly, 20, discovered she has the mutation, and is considering having both breasts removed to prevent it.

''Because I'm so young, they say I have time to think it through and still decide in time,'' she says.

Tracy Moss, of Freeport, volunteered for the study in the Bahamas. She was diagnosed with breast cancer this year at 43; her mother was diagnosed at 34, her sister at 33.

''I hope this study can say why this is happening,'' she says. ``Too many young girls in the Bahamas are getting breast cancer.''

A Canadian medical researcher who has studied breast cancer gene mutations around the world says that, if the UM team can narrow breast cancer in the Bahamas to a few culprit gene mutations, he can devise a screen to test every Bahamian woman for $50 each.

''We could do it once, for all time. It's genetic, so if your parents don't have it, you won't either,'' said Dr. Steven Narod, director of the Familial Breast Cancer Research Unit at the University of Toronto. Those found at risk could take preventive steps -- from surgically removing their breasts or ovaries to taking anti-cancer drugs such as Tamoxifen.

The UM researchers have joined the Bahamas Breast Cancer Initiative, which is trying to get women to be tested and set up a cancer registry to track the number of cancer cases in the islands.

In Freeport, the Cancer Association of Grand Bahama is recruiting volunteers for the new study. ''Women are very eager,'' says association director Norma Headley. ``They want information.''

STARTED IN 2002

The UM Bahamas breast cancer studies began in 2002, after Hurley and Bahamian medical colleagues noticed that women there were being diagnosed with cancer at earlier ages than other women.

Puzzled, Hurley and Nassau's Dr. Theodore Turnquest did a quick scan of breast cancer patients' charts from Princess Margaret Hospital and confirmed their suspicion -- 48 percent of the patients were diagnosed before age 50. In the U.S., less than one-third of patients are diagnosed that early.

''In the U.S., breast cancer is for older ladies -- 62 years old at diagnosis on average. That's a big difference,'' said Hurley, whose work is funded through the Braman Family Breast Cancer Institute at UM's Sylvester Cancer Center.

So they launched a study of 18 Bahamian breast cancer patients living in South Florida. In eight of them, researchers found one or more of three gene mutations that can predispose women to breast cancer.

Floyd, the Miami Gardens woman, discovered her risk through the UM study. Her mother, part of the study, carried the mutant gene, was diagnosed at 29 and died earlier this year at 47. Floyd, now 20, knows she, too, carries the mutation. Her sister, Stacey, 25, does not.

''I was a little depressed for a while when they told me,'' Floyd says. ``But with a lot of prayer I got through it.''

She still faces the decision of whether to have her breasts removed. ``I take it very seriously. If I decide, it will be in a timely manner.''

Since the 1990s scientists have known that mutations in two genes -- called BRCA1 and BRCA2 -- sharply increase a woman's risk of breast and ovarian cancer. Women who have the mutations have up to an 85 percent chance of breast cancer and up to a 60 percent chance of ovarian cancer.

`FOUNDER GENES'

Gene mutations vary widely. Across the U.S., only one in 100 people has a BRCA mutation. But in Ashkenazi Jews -- those of Eastern European ancestry -- it's one in 40. Three mutations found among Ashkenazi Jews are called ''founder genes,'' because they are believed to have arisen -- perhaps hundreds of years ago -- from a single common ancestor.

In the U.S., black women are less likely than white women to get breast cancer. But those who do get it die at an earlier age. At least 32 percent of black breast cancer patients are diagnosed before 50; among white women, it's 23 percent.

The Bahamas has no official cancer registry, so its overall cancer rates are unknown. Based on researching the 18 Bahamian families, Hurley and her team say they believe they are dealing with similar founder gene mutations that could go back hundreds of years.

''The mutation in the Bahamas probably came from West Africa as early as the 1500s,'' said Hurley. ``Some poor slave -- male or female -- had a spontaneous gene mutation in an egg or sperm cell. They happen all the time.''

But when they happen in groups that are isolated for geographical reasons (such as the Bahamians) or cultural reasons (such as the Ashkenazi Jews) they get passed around to a greater percentage of the population.

''Basically, the whole Bahamas is made up of 20 extended families -- super families -- that are tightly related,'' Hurley said. ``They've been there for centuries. A lot of them are related. You can recognize names from certain islands.''

Her hope: If a few founder genes can be shown to be responsible for most Bahamian breast cancer, doctors can develop an inexpensive test just for those genes, rather than screening for every known gene mutation, which could cost thousands of dollars per woman.

BETTER TESTING

''The benefit of finding founder genes is that you can offer more-targeted testing,'' said Talia Donenberg, a board-certified genetic counselor at UM/Sylvester Comprehensive Center and a member of the study.

Kay Capron understands. The Freeport resident, now 41, was diagnosed with breast cancer at 37, and was a volunteer in the first UM study. She can trace 11 family members with cancer on her father's side. His people came from Andros Island, named Donaldson.

''I did the gene testing and learned that the cancer was hereditary. I want to share my data so others can be informed,'' she said.