BOSTON -- Fighting breast cancer has become a family's mission after four of five sisters were diagnosed with the disease.

Paula was the youngest of the five Swanson sisters and the first to be diagnosed with breast cancer.

"I got the brunt of it. I thought it was because I could handle it better than my sisters. Then they were diagnosed and that blows that idea," she said.

Paula was first diagnosed in 2002. The cancer returned five years later and spread to other parts of her body. Then the sisters say the cancer metastized through their family.

Trish Swanson was diagnosed in November 2007. Paula and Trish called themselves the "Cancer Twins," until Debbie's diagnosis a month later.

"I had to tell my sisters on Christmas," Debbie Ryan said.

Then Lisa Swanson got the grim news on April Fool's Day.

Tests showed four of the sisters tested positive for a mutation in a gene known as BRCA 2, putting them at high risk for both breast and ovarian cancer. Their mother died of ovarian cancer at the age of 67.

Only the oldest sister, Gail Molla, tested negative.

"I felt guilty wondering why I was spared. Being the oldest sister and the caregiver, I thought somebody needs to take care of everybody," she said.

The sisters said they want to share their story in the hopes they can push for better testing and treatments for their seven daughters.