Hanna Saadeh - Screening Mammograms and Breast Cancer Deaths
Since many of our traditional medical beliefs are based on insufficient evidence, new discoveries continue to challenge and change the way we think and act. Many examinations and tests, which were once considered good and thorough medicine, have fallen out of favor because they have been shown to be more harmful than helpful.
The idea that a test or an examination can be harmful is relatively new. As an example, let’s take a woman who has a suspicious mammogram and is recalled for further testing. She has a breast biopsy, is found to have a contained cancer and has to undergo surgery. She subsequently develops an abscess, ends up with deformed breasts and has breast reconstruction. This leads to her hemorrhaging, thus requiring blood transfusions, and she suffers a reaction to the transfusions. She is discharged after spending a week in the intensive care unit. One must take into consideration the anxiety, fear, disillusionment, expense, and disruption of life, all of which could have been avoided because the contained cancer was but a microscopic diagnosis of no clinical significance. The woman could have lived a normal life and died from another cause, with the benign microscopic cancer still in her breast.
Since similar stories abound, it should be remembered the ultimate goal of any screening test is to save or improve lives. If screening tests detect abnormalities, which when treated, do not save or improve life, then such screening tests should be abandoned because their harms outweigh their benefits. Currently, the annual mammogram is accused of causing more harm than good because of the high recall rates for further testing and because of the frequent over diagnosis, both of which increase anxiety, expense, and harm, but do not seem to reduce the mortality from breast cancer. This new accusation has sparked a heated debate because the evidence remains inconclusive. Nevertheless, since the aim of debate is progress, I shall relate both sides of the argument, leaving it for women themselves to decide which side to choose.
The primary goal of mammograms is to reduce the huge burden of suffering that breast cancer wields on society. The Canadian National Breast Screening Study, which began in 1980, attempted to settle two questions:
A) Will intensive screening with annual mammography and breast examination for five years reduce the death from breastcancer in women 40-49 years old? The study found that after 25 years of follow-up, the death rate was not reduced.
B) Will mammography, added to careful breast examination, reduce breast cancer death in women 50-59 years old? Again, it was found that after 25 years of follow-up, the death rate was not reduced.
Moreover, about 22% of detected cases were over diagnosed and treated for cancers that were benign and would not have caused death. This contrasts with the trials done in the 1970s, which showed a 15% reduction in death rate. This discrepancy could have resulted because modern treatments are so much better, which renders earlier detection less important.
For women 60-69 years old, however, screening every two years may do more good than harm and is still recommended by most authorities. The Swiss Medical Board takes exception to that and no longer recommends mammography screening regardless of age.
A new X-ray method, known as tomosynthesis, when added to mammography, improves cancer detection, reduces recall rates and false positive results, and may reduce breast cancer deaths, but the benefit/harm ration still awaits the publication of outcome studies.
In contrast to the Canadian Study, fourteen relatively modern studies (2001-2010), done on women 40-74 years old, have shown a 25%-50% reduction from breast cancer deaths. Based on such studies, the American Cancer Society and other organizations continue to recommend annual mammograms for women 40 years or older.
To have a mammogram or not is a current controversy that can only be resolved by modern studies that may or may not show a significant reduction in breast cancer deaths. Until the time when such definitive studies become available, the decisions to recommend and to undergo mammograms will have to be individualized both by doctor and patient.
Meanwhile, obesity and physical inactivity, the two commonest risk factors that increase breast cancer, should continue to be targeted preventively. Such preventive measures are vital in the fight against beast cancer and have to be aggressively implemented regardless of the screening preferences of both the doctor and the woman.
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