The characters: Dr. Emens and her patients

Sun Special Report: The Trial of Their Lives

The doctor

Dr. Leisha Emens, 46, an oncologist and researcher at Johns Hopkins University, where she has worked for nearly a decade. She is the principal investigator on two small clinical trials of an experimental breast cancer vaccine she developed.

The patients

Annie Siple, 43, near Orlando, Fla. Entered Emens' second trial after her breast cancer spread to her liver and received her first shots in February. She lives with her husband and younger son and works as a waitress at a Disney World restaurant. The vaccine, to her, is as close to alternative medicine as she could find. She chose it to avoid what she considers the "poison" of chemotherapy.

Peggy Murphy, 57, near Lancaster, Pa. Entered Emens' first trial in October 2007. She complained of pain in her hip for years before doctors finally diagnosed it as a recurrence of the breast cancer she thought she had kicked. Her disease appears to be spreading. She lives with her daughter and grandchildren.

Darby Steadman, 38, Severna Park. Enrolled in Emens' second trial in April. She is scheduled for a fourth and final round of vaccine this month. The mother of two young children and the daughter of a breast cancer survivor, Steadman took the most aggressive approach to her breast cancer diagnosis: double mastectomy. She was told there was a less than 1 percent chance of recurrence, but the cancer came back.

Susan Marangi, 60, Parkville. Enrolled in Emens' first trial in December 2006, getting her last vaccination more than a year ago. It has been nearly 20 years since her first breast cancer diagnosis. She was cancer free for 11 years before she was told two years ago that her cancer had spread to her hip. Marangi is the unofficial leader of a loose-knit group of women in the trials who compare notes.