Wanda Willis was just 41 when she was diagnosed with breast cancer in 2003. To Wanda and her sister, Tina Hall, it was a frightening time. Both their mother and grandmother had had the disease and both died from its complications before age 50.

"The only thing we knew about cancer in our family was that it was a death sentence," remembers Tina, a special education teacher in Winston-Salem, North Carolina.

Fortunately, Wanda’s experience was different. Although her treatment was difficult – surgery, six months of chemotherapy, and six weeks of daily radiation treatment – Wanda bounced back and now feels better than ever. She walks six miles several days a week, has just finished her master's degree, and is starting a therapeutic massage organization for cancer patients called Touch Therapy.

"I feel great," she says. "My hair has come back. I feel stronger and more youthful than before. It's wonderful."

Among Wanda’s many activities is her participation in the Sisters Network, Inc., a national organization for African American breast cancer survivors. At one particular meeting, she learned of a project called the Sister Study, a 10-year clinical trial aimed at finding the causes of breast cancer through the study of women who do not have breast cancer, but have sisters who have had it.

The study looks at thousands of women across the United States and Puerto Rico, focusing on genetic and environmental factors that might be linked to breast cancer. Wanda immediately recognized the importance of this study and enlisted her sister, Tina, who saw the same value and more. “Because it was my way to support her [Wanda], I didn't have any reservations about it," Tina says of signing up.

Women who take part must answer detailed questions about their diet, jobs, hobbies, and other things. They also give samples of blood, urine, toenail clippings, and household dust.

“Giving samples was easy,” Tina says. Remembering details about her past – what she ate as a teenager, what products she used – proved harder. Now that she's completed those parts, though, all she has to do is a periodic telephone interview with researchers. The study does not require participants to take any medications or undergo other physical exams, and they are not asked to change their diets or daily habits.

So far, the study has enrolled 27,000 women, but researchers need another 23,000 to sign up. They're especially interested in recruiting ethnic and racial minorities – African Americans, Hispanics/Latinas, Native Americans, Asian/Pacific Islanders – because less is known about breast cancer in these groups than in Caucasian women.

That point is important to Wanda Willis. "If there's a clue linked to what we do culturally, then we need to be represented in the study as well," she says. “Breast cancer survivors of all races need to encourage their sisters to join the study,” she adds, “even if cancer is a difficult subject to broach. We can't just sweep it under the rug once we feel like we're well."

For her part, Tina discusses her participation in the study every chance she gets and distributes informational materials when possible. She takes pride in knowing she's doing her part to fight breast cancer. And hopes the study helps researchers find a cure for breast cancer – or even better, a way to prevent the disease.