By CLARK ROGERS, MD
A mammogram is the only breast cancer screening method proven to save lives. Despite recent controversy in screening mammogram guidelines, the American College of Radiology - the professional organization most responsible for regulating the production and interpretation of mammograms - continues to recommend annual screening mammograms beginning at age 40 for the average risk woman. Annual mammograms should continue for as long as she remains in good health.
I am an advocate for screening mammograms. I encourage my family and friends to follow the guidelines of the American College of Radiology. I recommend that my patients to do the same. Approximately 25% of women who die from breast cancer are diagnosed in their 40s according to the American Cancer Society. Studies indicate that the most lives are saved when screenings begin at age 40 rather than a later age. This is agreed upon by the professional organizations in the United States that provide screening mammogram guidelines including the American College of Radiology, the US Preventative Services Task Force and the American Cancer Society. If the organizations agree, why the controversy on when to begin screening and how frequently to screen? Why do the American Cancer Society and the US Preventive Services Task Force recommend beginning screening at a later age with decreased screening interval frequency? Over the next few paragraphs, I will discuss the screening controversy and why I believe the American College of Radiology recommendations are best for patients. The goal is to provide potential guidance to clinicians, particularly those in primary care, who frequently deal with these questions from patients.
Breast cancer screening guidelines vary due to different weight given the potential harms versus the benefits of screening mammograms. While the main benefit of mammography is well known - reduced mortality due to early detection of breast cancer - like any medical test, there are potential risks. Two concerns are overdiagnosis and patient anxiety.
Overdiagnosis is the idea that some cancers detected in the breast may never result in the death of the patient. If left alone, these cancers would not pose any threat. Current thought is that many but not all low-grade cancers such as ductal carcinoma in situ progress to invasive malignancy and can potentially metastasize; however, it is difficult to determine which cancers would never progress to threaten the life of the patient. Most estimates of overdiagnosis due to screening mammography are between 2-10%.
From a practical standpoint, delaying the age of initial screening from 40 to 45 or even 50 and decreasing the frequency of screening mammograms, as suggested by the American Cancer Society and the USPSTF, is a poor way to combat overdiagnosis. While it is true that fewer nonlethal cancers would be detected, the tradeoff is decreased detection of lethal cancers or detection at a later stage when treatment may be less effective and surgery more invasive. I submit that underdiagnosis of cancers that could result in a woman's death should be the major concern! Until we can distinguish which cancers will progress from those that will never harm a patient, I believe it is in the best interest of our patients to err on the side of not missing the lethal cancers.
A second potential harm of mammography cited by the US Preventative Services Task Force as reason to decrease screening frequency is the anxiety associated with false positives from screening recalls and biopsies. It is true that most breast biopsies do not result in the diagnosis of breast cancer; most biopsies yield benign results. However, in a study from 2004 reported in the Journal of the American Medical Association, 98% of patients who experienced a false positive in a screening test did not regret having the test performed. Another study revealed that the majority of women felt that one life saved was worth 500 false positive results.
As a radiologist, I have regular discussions with patients about biopsies and the potential false positives associated with mammography. In my experience, most women would choose the anxiety associated with a false positive and a possible biopsy over leaving a breast cancer undetected.
Mammography saves lives. The advent of screening mammography coupled with improved treatment has resulted in marked decrease in breast cancer related death over the last several decades. On the other hand, the potential harms of overdiagnosis and anxiety associated with mammography is much more difficult to quantify. I advocate for annual screening mammography beginning at age 40 because I believe underdiagnosis of lethal cancers should be the primary concern. In my experience, most patients agree.
Clark Rogers, MD, is a board certified diagnostic radiologist, sub-specialized in breast imaging for Radiology Specialists of Florida at Florida Hospital. He earned his medical degree at the University of Kansas School of Medicine and following graduation completed his residency and fellowship in breast imaging at Indiana University.