More Mammograms May Not Always Mean Fewer Cancer Deaths

The researchers found that when breast cancer screening increased by 10 percent, breast cancer was diagnosed 16 percent more often overall.

(Reuters Health) – Breast cancer screenings may not lead to fewer deaths but may lead to overdiagnosis, US researchers suggest. But this have not seem to be to be the occasion.

The group performed an environmental evaluation of 16 huge number of young women across 547 areas whom advised to Surveillance, Epidemiology and End Results cancer registries in 2000. Of these women, 53,207 were diagnosed with breast cancer that year and followed for the next 10 years.

The causes of the investigation, found in the notebook JAMA…

So what does all this mean for women concerned about breast cancer?

Routine screening for breast cancer was introduced in Britain 25 years ago, with the hope that catching symptoms early would enable the cancer to be treated before it had spread. “We feel that our study raises important questions about the benefits of mammography screening, but it certainly does not answer them”.

Other women might undergo gruelling chemotherapy to treat small, slow-growing tumours which might never have troubled them if they lived on in ignorance.

It is not only recommended that patients and doctors share decision making about screening, many states, including Pennsylvania, have laws requiring doctors to inform women about the density of their breast tissue.

Across US counties, there was a correlation between the extent of mammogram screening and breast cancer incidence – particularly small cancers – but not with breast cancer mortality, they say.

In the United Kingdom, women aged 50 to 70 are invited for a mammogram every three years.

Some experts are sceptical about the benefits – arguing that catching a tumour early pushes women into having potentially harmful treatment such as radiotherapy and chemotherapy – in some cases completely unnecessarily.

Just last month, researchers from the University of Copenhagen warned of the psychological strain of false-positive mammograms in a study in the journal Annals of Family Medicine.

The team looked at studies on screening for breast, colorectal, cervical, prostate and lung cancers that were started in Sweden in the 1960s and 70s. The x-ray tests have found mostly tumors that would have stayed harmless if untreated, yet have resulted in over-diagnosis, according to The Los Angeles Times.

But there was no reduction in the number of large tumours – which should have been seen if the cancers had been spotted before they grew. “The simplest explanation is widespread overdiagnosis, which increases the incidence of small cancers without changing mortality, and therefore matches every feature of the observed data”, the authors write. “As is the case with screening in general, the balance of benefits and harms is likely to be most favorable when screening is directed to those at high risk, provided neither too frequently or too rarely and sometimes followed by watchful waiting instead of immediate active treatment”.

Overcompensating for uncertainty in risk can result in additional screenings for women who may not actually have higher risk, and fewer screenings for women who are “falsely reassured” because they have lower breast density, according to authors Jennifer S. Hass, of Brigham and Women’s Hospital in Boston and Celia P. Kaplan of the University of California, San Francisco.

“However, our findings are quite tentative for mortality because the data are very noisy”, he added.

A 10-percentage point increase in screening also increased the occurrence of breast-conserving surgical procedures (RR = 1.24; 95% CI, 1.15-1.34).