A new research study has concluded that annual mammograms in middle-age women have no impact on breast cancer death rate. The researchers suggest that physical examination, in isolation, is just as effective as mammography. The study was published in the Feb. 11 issue of the British Medical Journal (BMJ), entitled Twenty Five Year Follow-Up for Breast Cancer Incidence and Mortality of the Canadian National Breast Screening Study: Randomised Screening Trial.
Mammography screening is regularly performed to reduce the breast cancer mortality rate, with the principal ambition of achieving an early diagnosis. The authors of the paper explain that a direct relationship cannot be drawn between a patient’s survival and diagnosis using mammography. The group indicate that mammogram screening is prone to over-diagnosis, which refers to the possibility that a screen-detected cancer might not manifest as a “clinically apparent” medical issue, during a woman’s lifetime. The role of mammography in over-diagnosis and, therefore, over-treatment remains a source of considerable debate; some, however, consider the potential benefits to outweigh the harm done through over-diagnosis.
During a 25-year study, the researchers set about trying to evaluate the role of mammography in breast cancer screening. The study incorporated around 90,000 females, aged between 40 and 59, who had not received a mammogram in the 12 months prior to participation in the research, and had no history of breast cancer.
The participants had a physical breast exam and were tutored on appropriate breast self examination, by trained physicians. Women between the ages of 40 and 49 were randomly assigned to two groups – those who would receive mammography, and those who would not receive mammography. Participants allocated to the mammography group were scanned over a five-year period and also received physical examination. Meanwhile, those assigned to “no mammography” simply received physical examinations and the usual care in the community. Women aged between 50 and 59 were also divided into the afore-mentioned groups and investigated in the same manner.
Ultimately, the researchers found that the breast cancer death rates were similar in women who underwent regular mammography, relative to those women who simply received physical examination. After 20 years, 3,133 females in the “no mammography” control group had been diagnosed with breast cancer, while 3,250 female subjects from the “mammography” group had been diagnosed with the pathology. 500 women from the mammography group had died from breast cancer, compared to 505 women from the control group.
Furthermore, the study found that one in five cancers detected using mammography – which were subsequently treated – posed no threat to health, and did not need treatment with conventional techniques, such as surgery, chemotherapy or radiation.
In concluding, the researchers call into question the role of mammogram screening and suggest there is a need for policymakers to reevaluate its clinical use. Although the group accept their study’s findings may not be applicable to every country, they suggest the most technically advanced nations should have their screening practices “urgently reassessed.” Nonetheless, they encourage continued efforts to improve early diagnosis of breast cancer and the quality of clinical care provided to sufferers.
According to The New York Times, Dr. Richard C. Wender, the chief of cancer control for the American Cancer Society, has indicated that an expert panel is currently involved in reviewing all research into mammography, including the latest Canadian study; according to Wender, any resultant policy changes would likely be issued later on in the year. However, in looking at all of the accrued data from clinical trials of mammography, he points out that the breast cancer death rate is reduced by 15 percent for females in their 40s, and by 20 percent in older women.
On the other hand, a number of researchers have suggested it is less important to find these cancers early, due to the introduction of enhanced treatments, including tamoxifen. Researchers have also now found that certain cancers grow much slower than initially suspected and, thus, many may not require treatment. For example, ductal carcinoma in situ (D.C.I.S.) – a noninvasive condition, found during mammogram screening – is restricted to the milk duct. However, D.C.I.S. can, potentially, progress to become an invasive cancer. Regardless of size and location, however, most detected breast cancers are treated.
Currently, screening guidelines for breast cancer differs, from country to country. Thus far, only Switzerland has considered suspending mammogram screening practices, with the Swiss Medical Board suggesting no additional mammography screening programs be implemented.
The American Cancer Society recommends annual breast cancer screening, commencing at the age of 40. However, the organization suggests females over the age of 30, that are “at high risk” of developing breast cancer, should have yearly MRI and mammogram scans.
By James Fenner