This post is based on my recent news report in Digital Journal
Results of a new study from Norway show that 15 to 25 percent – or about one in four – cases of breast cancer found through routine screening mammography is over diagnosed and would never have posed a health risk for the women had they never been found. Results of a long term study published in the April 3 issue of Annals of Internal Medicine, found that number of cases of invasive breast cancer in women aged 50 to 69 was the same in Norwegian counties that introduced screening programs and those that had not. This study adds more fuel to to ongoing debate about the benefits of screening mammography versus the risk of false positives – including additional exposure to radiation, unneeded surgery, and chemotherapy, as well as the mental trauma experienced.
Nearly 40,000 women were tracked for a decade, starting in 1996. About a quarter of the women were diagnosed with benign tumors or very slow-growing tumors that would never cause symptoms, spread, or cause death. That worked out to 6 in 10 women being over diagnosed for every 2,500 screened. Without surgery, it is currently impossible to tell which tumors are benign and which pose a risk.
However, many of these women chose to undergo mastectomies, which ultimately proved to be unnecessary. This directly contradicts messages from government and non profit organizations that screening reduces mastectomy rates This study is in line with several earlier European studies that also reached similar conclusions about over-diagnosis of cancer with mammography screening. Women diagnosed with ductal carcinoma in situ, a different form of cancer, were excluded from this study.
So what’s a woman to do? For decades, we have been getting messages about getting annual mammograms. But with each new study, more doubts are raised about risk vs. reward. The American College of Radiologists, a group that certainly has a strong interest in promoting screenings, said that women at elevated risk should also add ultrasound to their annual exams. For some women, this makes sense — for example, women with very dense breast tissue or those with at least one other risk factor such as family history. But what about the majority of the 40+ population?
Even breast cancer advocacy groups are divided. Perhaps Breast Cancer Action, which accepts no funding from pharmaceutical or other corporations that might profit from cancer diagnoses, had the best advice: there is no one “right” answer — women need to weight the risks, consider their own medical history, and look at other options, such as clinical breast exams. There are many ways to manipulate the numbers, and to spin the clinical results.
If your life, or your sister’s or mother’s, is the one saved by a screening mammography, there’s no question that it was the right option. However, the majority of women are not in a high risk category – so risks, benefits, chance of false positives or negatives, as well as other detection options, need to be part of a conversation with their physicians — and ultimately has to be a woman’s personal decision.