Breast check scan ‘is justified’ despite number of harmless tumours, says cancer expert

An Irish cancer expert insists there is still “clear justification” for breast screening, even though a study found that it resulted in one third of patients being treated for harmless tumours.

A Danish study of women aged 50 to 69, found that one in three tumours and early cancer cell clusters found in the milk ducts are over-diagnosed.

It suggests that the benefits of breast cancer screening have been overstated and it can lead to patients having unnecessary surgery and harmful treatment.

The Nordic Cochrane Centre study, published in the Annals of Internal Medicine, looked at women diagnosed with breast cancer from 1980 to 2010. Women in areas offered screening were compared to those in areas without it, and adjusted to take into account changing cancer rates over time.

The head of research at the Irish Cancer Society, Dr Robert O’Connor, said just over one in 10 women would develop an invasive breast cancer over their lifetime. He said it was quite common for an early pre-cancer to develop in the breast, particularly in the milk ducts.

However, it is “next to impossible” without surgery to know whether a “lump” is going to become an invasive cancer. He said breast mammography is a difficult and challenging technique to interpret, and it does pick up lumps that sometimes might not go on to form a cancer.

“It is only by picking those up that there is an opportunity to make that decision and make that call,” said Dr O’Connor.

However, he could not agree that the benefits of breast cancer screening have been overstated, or that it can lead to patients having unnecessary surgery and harmful treatment.

Dr O’Connor said it is not a black and white issue and that the study was making an academic argument against over-diagnosis.

He believed there was still “clear justification” for women availing of the free breast cancer screening service provided by BreastCheck: “In reality, if a woman has a lump in her breast, it absolutely needs to be investigated.”

Dr O’Connor said surgeons are increasingly only seeing small breast tumours because a lot of them are being picked up by the BreastCheck service before they become large and harder to treat life-threatening cancers.

“The majority of women are cured of their breast cancer, in many cases because it is caught early when it is treatable,” he said.

According to the Irish Cancer Society, more than 2,600 new cases of breast cancer are diagnosed in Ireland each year, and 74% of Irish women with breast cancer discover the lump themselves.

BreastCheck, the national breast screening programme, offers free mammograms to women aged 50-64. Eligible women are invited on an area by area basis, for free screening every two years. Women can register for BreastCheck by calling freephone 1800 45 45 55.