But the tragedy of the Woods sisters, two of whom died, led to scientists discovering the genetic reasons underlying breast cancer, according to a consultant who treated them.

The surviving three sisters had mastectomies, and now the next generation of the family is being monitored for a gene mutation that leaves women with up to an 85% chance of getting breast cancer.

Research by Peter Daly, a consultant at St James’s hospital, helped identify BRCA2 as the cause of the sisters contracting the disease. Scientists have identified two mutations in the BRCA1 and BRCA2 genes that increase cancer risk. Daly estimates that 5% of the 1,500 new cases each year are because of a genetic predisposition.

“Before the Woods case came along we knew of the existence of BRCA1, but it was mainly through them that BRCA2 was discovered,” he said. “The family seems to carry a particularly aggressive form, and it strikes young.”

The professor said screening has been made available for Woods family members who want to check if they are carrying the gene. But lack of funding means other families who have a high incidence of cancer are not being offered proper screening services, he claims.

A daughter of Marian Woods, one of the women who died, has already opted to have her breasts removed after being informed she carries the gene.

In 1982 Ann Woods, then aged 33 and a mother of twin daughters, was the first of the sisters to discover she had breast cancer.

“I had lost a lot of hair and decided to go to my GP to tell him that I thought I had a lump on my breast. I was examined and he said yes, it was the size of a large egg,” she said. “That was on a Tuesday. On the Thursday I went to see a consultant and almost immediately had a mastectomy. After that I had a year’s chemotherapy.”

Just as Ann Woods started to recover, her sister Alice was diagnosed with the same disease. Then a third sister, Marian, realised that she had a lump. She had one breast removed, and was tested again, only to learn that her other breast was affected.

Doctors asked the other two sisters to have tests. While Breda was given the all clear, her eldest sister Betty, 46, tested positive.

She recalled: “The doctor said, ‘you have a lump’. I didn’t believe him. But he got my finger and showed me where. He said it is coming out, whether it is malignant or not. It was Christmas and we were all trying to make it as good as possible while looking after Marian’s children and realising Alice was terminally ill.”

Daly began genetically screening the sisters. DNA tests eventually confirmed that the family had inherited a rare breast-cancer gene.

Alice died in August 1987. By 1990, when Breda was told she too had breast cancer, Marian, the youngest, was seriously ill. She died the following year.

Marian’s eldest daughter Jessica was 13 at the time. She and her siblings were placed in an orphanage in Dun Laoghaire so they could be kept together.

Ann’s daughter Tanya, 30, a mother of three, was one of the first of the next generation to be found positive. “Sometimes you are struck with fear and other times you get on with life,” she said.

Marian’s daughter Jessica, now 26, didn’t hesitate to have surgery when she tested positive. “When I found out, there wasn’t really much of a waiting period because I didn’t want to know if I had cancer or not. All I wanted to know was if I had the gene. There were no guarantees that I was safe and I wasn’t willing to take my time making a decision that I knew I would have to make eventually.”

Daly says Ireland is behind Europe in terms of cancer- detecting genetics. “Medical genetics was seen as a dirty word for a long time because people associated it with abortion. We have a lot of catching up to do.

“We hopefully will screen all women every year from the age of 50, which is the maximum risk time for breast cancer. But for women like those in the Woods family, this is no good. They need to be singled out and given attention.”

The Woods will tell their story on RTE’s Would You Believe programme next Sunday at 10.25pm.

Explore Health News

• Swine flu

Times Recommends

• Family cuts its waste to one binful a year
• Cameron can learn from Thatcher in 1979
• VAT is back ... and it's confusing