Breast cancer screening not linked to life expectancy

Washington: According to a recent study, fewer and fewer women died from breast cancer in recent years, but surprisingly, the decline has been just as large in the age groups that are not screened. The decline is, therefore, due to better treatment and not screening for breast cancer.

As part of the study, the researchers followed all Norwegian women aged 30-89 and identified those who developed breast cancer in the period 1987-2010, before subsequently comparing the number of deaths before and after the screening programme was introduced.

According to Henrik Stovring, one of the researchers, the result didn't favour the breast cancer screening programme. The Danish screening programme was progressively introduced from the early 1990s and was offered nationally to everyone from 2007, three years after the Norwegians, who supplied data for the Danish-Norwegian research project.

"The important result is that we do not find a beneficial effect of breast cancer screening any longer. The original randomised trials examining breast cancer screening were conducted way back in the 1980s, and they showed an effect, but the fact is that the better the treatment methods become, the less benefit screening has," said Henrik Stovring.

Here, he pointed towards one of the paradoxes of screening, the popular but erroneous belief that if breast cancer patients who have been screened to 'live longer' than other breast cancer patients, then screening works. The problem was that with screening, medical doctors detected cancerous tumours earlier than they would otherwise have done. But even if someone who has been screened lives longer as a patient, it is not certain that their life as a whole will be longer. It was important to account for this fact, and the new study showed that screening does not lead to women living longer overall - and this is the study's most important finding.

"The women who were invited to screening live longer because all breast cancer patients live longer, and they do so because we now have better drugs and more effective chemotherapy, and because we have cancer care pathways, which means the healthcare system reacts faster than it did a decade ago. But it does not appear that fewer women die of breast cancer as a result of mammography screening," said Henrik Stovring.

He also pointed out that it is not always beneficial for a woman to be diagnosed with a tiny cancerous growth of e.g. a millimeter in diameter at a mammography. Some of these small nodules are so slow-growing that the woman would have died a so-called natural death with undiagnosed cancer if she had not been screened.

"Now what happens is these women are instead given a diagnosis which isn't going to make anyone happier. Such a breast cancer diagnosis both makes life more difficult and costs a lot of money, but does not ultimately make a difference. The problem is that we were not able to tell the difference between the small cancer tumours that will kill you and those that will not," said Henrik Stovring.

Here he addressed the issue of overdiagnosis which is a growing problem in all Western countries where the approach to medicine and examinations is extensive and where national screening programmes are prevalent.

"It's certainly not my task to decide how the research results should be used, but my suggestion would nonetheless be that we should get together and begin to investigate whether it would beneficial to do something other than screening and whether this could have a better effect. If a doctor could instead examine women's breasts with his or her hands, what is known as palpation, at regular intervals, then we would avoid much of the overdiagnosis," says Henrik Støvring.

The findings are present in the Journal International Journal of Cancer.