Treating precancer of women’s breasts saves lives

Macquarie University’s Professor John Boyages is tackling head on recent claims doctors are over diagnosing and over treating a type of breast cancer called ductal cell carcinoma in situ (DCIS). This precancerous state, also known as cancer stage 0, occurs when abnormal cells are found in a woman’s breast ducts but haven’t yet escaped to become lethal breast cancer. In a new book “DCIS of the Breast Taking Control” Professor Boyages says around 40 women a day are diagnosed with breast cancer and another four women are diagnosed with DCIS.

All of these women with DCIS will have a lumpectomy or a mastectomy but follow up treatment including radiotherapy and hormone treatment varies. On study found around 38 per cent of women who miss out on this follow up treatment will go on to develop invasive breast cancer over the next 30 years and more than half those women will die. “In my opinion many of these deaths could have been prevented,” he says. The claims about over diagnosis of breast cancer have “caused a lot of confusion” so Professor Boyages reviewed the evidence during a four year sabbatical at Oxford University. The result is a book that talks women through their treatment options and provides the evidence they need to make a decision about what treatment to have.

Detected by a mammogram … DCIS is a precancer of the breast.. Source: News Corp Australia

A study of over 1,600 DCIS patients found the risk of further DCIS or breast cancer in the same breast was 26 per cent if women had surgery alone. The risk fell to 20 per cent if women with DCIS had surgery and used the hormone therapy tamoxifen. The risk of a further breast event was reduced to 9 per cent if surgery was followed by radiation and six per cent if radiation and tamoxifen were used. Professor Boyages says the beneficial effect of treating these precancerous abnormalities is reflected in cancer statistics. The mortality rates of Australian women from breast cancer plunged 35 per cent between 1989 and 2008 but have risen slightly, by two per cent since then. Deaths from breast cancer fell most in women aged over 70 years of age and Professor Boyages says this is because of the detection and treatment of DCIS after breast screening was introduced. Australia’s Health Ministers’ Advisory Council Standing Committee on Screening and key cancer groups have put out a position statement that acknowledges that some of the abnormalities detected in breast screening might never progress to become symptomatic in a woman’s lifetime. Based on the UK and European reviews it estimates that for every 1000 women in Australia who are screened every two years from age 50 to age 74, around 8 breast cancers are found and treated that would not have been found in a woman’s lifetime. However the statement notes it is not possible to precisely predict at diagnosis which abnormalities won’t progress. “Research is needed, including molecular and genomic research, to find means of identifying cancers that would be of minimal risk of progression and therefore could be managed more conservatively,” the statement says. Originally published as Breast cancer deaths preventable