The sa国际传媒 Cancer Agency鈥檚 decision to reduce mammogram screening has taken many women aback. That鈥檚 hardly a surprise. Cancer specialists have spent decades emphasizing the importance of early detection. Now they appear to be reversing themselves.
According to the agency鈥檚 new guidelines, women aged 40 to 74 with no family history of breast cancer should receive mammograms every two years instead of one.
For women 75 and over, the agency advises having the test every two to three years, or discontinuing it entirely if a physician agrees.
This was bound to be controversial. Cancer has replaced heart disease as the leading cause of death in sa国际传媒. Any relaxing of our vigilance, no matter the reason, takes a lot of explaining.
Perhaps it was thought there was nothing revolutionary about the decision. A federal task force in 2011 made similar recommendations.
And medical science is constantly evolving, as better treatments are found.
But there is one aspect of this course correction that sets it aside from others. It flies in the face of everything we鈥檝e been told about cancer.
There are growth charts scattered across the Internet that detail the grades and stages that tumours progress through. They correspond inexorably with ascending mortality rates. The message is simple 鈥� or appears to be: Catch it quickly or else.
So what happened to bring about this slow-walking of mammograms?
In part, the new guidelines reflect some welcome advances in clinical treatment.
The development of targeted anti-cancer drugs such as Herceptin and tamoxifen has made it possible to treat large tumours more successfully.
There is also the reality that screening programs such as mammograms inevitably produce 鈥渇alse positives.鈥� These are test results that look suspicious, but on further examination turn out to be innocent.
And that further examination comes with a cost. It exposes thousands of patients to follow-up procedures, such as a needle biopsy, that cause discomfort and needless anxiety.
Yet it is difficult to be confident that the science is entirely settled. The medical director of the screening program, Dr. Christine Wilson, said she did not expect more deaths, bigger tumours upon detection or more aggressive treatment because of the changes.
But a radiologist who was consulted about the new guidelines, Dr. Paula Gordon, was clearly uncomfortable. Gordon believed 鈥渢here will be women for whom two years is too long to wait between mammograms.鈥�
And she feared that if tumours are detected later, 鈥渨e may start to see more mastectomies 鈥� instead of lumpectomies.鈥�
That would seem to imply that some tumours might indeed be larger upon detection, and require more aggressive treatment.
Meanwhile, a British study found that while mammography does result in tumours being treated that posed no threat, for every one such case, two lives were saved. (Some cancers grow so slowly, they never endanger the patient鈥檚 health.)
Differing views and duelling statistics, of course, are common in science. The preponderance of evidence might very well support the Cancer Agency鈥檚 decision.
And the annual misery of undergoing a mammogram is a weight many women would happily see lightened.
Yet this is a difficult equation to balance, and all the more so because some of the factors are subjective. Anxiety is not easily reduced to hard numbers. The value of an individual life can be lost in mass statistics.
Fortunately, there is at least a partial solution. The cancer agency will continue to provide an annual mammogram to women in the test age group who wish it. sa国际传媒 is one of just three provinces to offer this option.
With opposing voices still speaking out, this has the feel of an experiment, and a rather large one at that.
