Worldwide, breast cancer is the most common cancer (other than skin cancers) and the second most common cause of cancer deaths among women.
Screening with mammography is recommended based on age, risk factors and overall benefit to the patient. Large Trials conducted in the Western population have shown about a 20% reduction in the likelihood of dying from breast cancer with annual screening mammography.
Typically, this is recommended starting at age 50, every other year for women at average risk. Between 40-50 years of age, the recommendations are individualized based on the risk factors for the patient. A baseline at age 40 and then every 2-3 years until age 50 may be a reasonable option. The age of cut off for mammography is not clear. It is not so much the numerical age as the physiologic age of the patient that matters. However, there is no clear-cut benefit beyond age 75.
This does not apply to high-risk patients such as patients with a gene e.g., BRCA mutation who may need MRI screening yearly along with mammography starting at earlier ages. Patents with 2-4 fold increase risk of breast cancer should also consider yearly mammogram between ages of 50-75 and every other year starting at age 40.
Risk factors typically include genetic mutations such as BRCA, early onset of menstrual cycles, late onset of menopause, late or no childbirths etc.
So, why the controversy regarding screening when studies have shown a decrease in mortality? Some of this comes from the potential complications with all screening, such as false positive mammogram possibly leading to anxiety, more frequent imaging, unnecessary biopsies etc. there is a small radiation exposure associated with mammography which in itself can lead to a small risk of breast cancer over a number of years
When routine mammographic screening was first introduced in the US, there was an increase in the incidence of breast cancer, more cancers were diagnosed which has led to the concept of “over diagnosis”. Are we diagnosing small cancers, which may never truly cause any problems during the life span of a woman? Currently, there are no methods available to determine which early cancers may progress to actually cause life-threatening problems in a woman.
This is of major concern as it may lead to treatments such as surgery, radiation etc which may result in harm.
Mortality from breast cancer has been declining over the last few years; some of this has been attributed to screening, but also to the major advances in treatment. The argument is made that patients diagnosed without screening will also likely survive breast cancer with modern day treatments.
However this generalization does not take into account that without awareness of screening and education as well as close relationship with a family physician or gynecologist many of these cancers may be diagnosed at a late stage leading to increased mortality once again from breast cancer. We have made too much progress to return to Ground zero. There should be a well thought out, individualized plan for each woman in conjunction with her Primary provider taking into account her risk and preferences. Mammography guidelines serve as a good template for such a tailored plan.