Mammograms never detect “early” breast cancer. By the time a cancer is visible to the human eye on a mammogram, it is already teeming with over a hundred billion cancer cells—which have been there for at least eight years—and it already has had ample time to spread to other parts of the body. In the majority of cases, the cancer has spread outside the breast, but the small groups of cells that have traveled to other parts of the body may be undetectable for years.
Most breast cancers found on mammograms, even the ones with negative lymph nodes that appear to be localized, will later be found to have metastasized. Lumpectomy for breast cancers that are thought to be localized only stop the cancer in a minority of cases, because in most cases microscopic cancerous cells already have left the breast. Women with larger tumors or with positive lymph nodes are treated with radiation and then chemotherapy in an attempt to destroy both the localized cancer cells and those that have migrated.
Mammograms enable us to treat more patients who are found to have breast cancer, but if the treatments are not very effective, what good is it to detect it earlier? Chemotherapy for breast cancer still should be considered experimental, because the chemotherapeutic agents used have a dismal track record in producing long-term survival of more than 15 years. Chemotherapy has been shown to offer some survival benefit in young (pre-menopausal) women with breast cancer, because the cancer is more aggressive in that age range, but not a significant increase in life expectancy in older women.1,2 More aggressive cancers are more sensitive to chemotherapy.
Mammograms done in the thirty-five to fifty age range—before menopause—are even more controversial. Many respected medical authorities are clearly against mammograms in this age group. First of all, the risk of having breast cancer before age fifty is about one in a thousand. The dense breast tissue, and the high incidence of benign disease of the breast in young women, leads to decreased accuracy of mammograms. The chance of having breast cancer in this age group may be exceptionally low, but the chance of having an abnormal finding, necessitating further views, ultrasounds, and repeated tests and biopsies, is quite high.
In 1995, a meta-analysis of thirteen studies found no evidence that mammograms before age fifty saved lives. That same study did show a benefit for women over the age of fifty. Researchers at the RAND Corporation, a think tank in California, performed a cost/benefit analysis and did not recommend women below age fifty receive mammograms because—at a cost of over 1.1 billion dollars annually—there was no evidence of benefit.3
In January 1997, a National Institute of Health consensus conference was conducted to consider whether or not screening mammography reduces breast cancer mortality among women aged forty to forty-nine. The twelve-member panel represented the fields of oncology, radiology, gynecology, geriatrics, and public health. Thirty-two experts presented scientific data to the panel. The panel, working with this data and with data in the scientific literature, concluded that mammography recommendation for women in their forties was not warranted.4
Since this time, most researchers reluctantly have been forced to accept the consensus that mammograms are not beneficial in this age group. Many greeted this conclusion with dismay and outrage. Other groups, most notably the American Cancer Society and the American Medical Association, reaffirmed their recommendations that even these younger women should get annual mammograms. By contrast, the Canadian Task Force on Preventive Health Care, the American Academy of Family Physicians, and the American College of Physicians do not recommend routine mammograms in the age range of thirty-five to fifty.
For more on The Mammogram Debate check out these posts:
- On the Ship of False Hope
- Multibillion Dollar Industry
- A Campaign of Fear
- Facts vs. Vested Interests
- Cause or Cure?