Breast cancer continues to be the second most common cancer among women and is the second leading cause of cancer death for women. One out of eight women will be diagnosed with breast cancer in their lifetime. It has been proven that earlier detection of breast cancer saves lives. When tumors are detected at an early stage, patients have more options for treatment.
With the clear advantages of early breast cancer detection, why is there controversy over screening methods and recommendations for detecting breast cancer? There are several reasons, and it also depends on whom you ask.
In 2009, the United States Preventive Services Task Force (USPSTF) released new recommendations for breast cancer screening. The panel recommended that screening mammography should begin at age 50 and continue every two years. They also recommended that clinicians stop teaching women to do self-breast exams. This was a marked change from the previous guidelines of the American Cancer Society, American Medical Association and numerous other groups that had recommended annual screening at age 40. The panel cited numerous reasons for its recommendations, including “anxiety” from needless biopsies, radiation exposure and overutilization of expensive resources. It is interesting that they did not deny the fact that screening mammography saves lives. It is also interesting to note that no breast imagers, breast surgeons or breast oncologists were on the USPSTF panel.
The questions raised by the USPSTF highlighted the challenges that any national screening program faces. To be effective, a screening program needs to be sensitive, affordable, accessible and safe. However, not all breasts are the same, and what works well for some does not for others. With that in mind, Moffitt is developing a “personalized” screening program tailored to meet the individual needs of every patient. We are examining the factors that limit evaluation and hinder our ability to diagnose breast cancer. These are multifactorial and include breast size and density, family history, genetic factors, environmental exposure and medical history.
Not All Breasts Are the Same
The sensitivity of mammography ranges from approximately 40 percent to 90 percent. This wide range is primarily due to differences in breast tissue density. There are four categories of breast density, ranging from completely fatty to extremely dense. Mammographic sensitivity for detecting breast cancer is in the 90 percent to 95 percent range in the low density (fatty) category of breast tissue. Conversely, in women at the other end of the spectrum with extremely dense breast tissue, the sensitivity of mammography is in the 40 percent to 50 percent range. This issue has prompted changes in some state laws, requiring radiologists to notify women with extremely dense or heterogeneously dense breast tissue that they face increased risk of breast cancer and that additional, more sensitive modalities such as ultrasound and MRI should be considered to evaluate them. Some states are even requiring insurance companies to pay for these more expensive screening exams.
At Moffitt, we are researching automated breast density evaluation for digital mammography. All of our units are digital, which offers greater flexibility during the exam and provides a more detailed image of the entire breast. Digital images allow for excellent visualization of cancer and findings suggestive of cancer, allowing us to make a diagnosis at an earlier stage. When a screening exam results in the need for a diagnostic exam, we utilize the appropriate digital mammography unit best suited for that woman’s individual breast size and density. By tailoring the exam, we reduce unnecessary extra views and limit exposure to radiation.
Recently, the safety of mammography has come under question. The public is becoming “radiation” conscious. Currently the dose of a four-view screening mammogram is approximately 4.0 mGy. To put that in perspective, the amount is slightly higher than yearly background cosmic radiation that you absorb by being alive. Digital mammography has an even lower dose. This is becoming especially important in cases where the patient requires mammographic imaging prior to the age of 40. If a patient has a strong family history of breast cancer, we begin annual screening 10 years before the diagnosis was made in the patient’s nearest first-degree relative. For example, if a mother is diagnosed with breast cancer at 45, her daughters should begin annual screening at 35. As breast cancer awareness increases, we are seeing increased numbers of young women with breast cancer.
To summarize, screening mammography saves lives, and the amount of radiation from a high-quality digital machine is very low. Screening should begin at age 40, or sooner if you have a strong family history of breast cancer or a genetic condition that predisposes you to breast cancer. Self-breast exam is important, as are yearly visits to a gynecologist. Mammographic screening should be performed at an American College of Radiology-accredited facility that utilizes digital mammography.
Dr. Mooney is Director of Breast Imaging and the Moffitt Cancer Center/University of South Florida Breast Imaging Fellowship Program. Moffitt provides screening and diagnostic mammography at our McKinley Outpatient Center and Moffitt at International Plaza. We offer a team approach. Our subspecialty trained radiologists work closely with our breast surgeons, oncologists, radiation oncologists, genetics counselors, nurses and other allied health professionals to offer state-of-the-art breast cancer screening and treatment.
Adapted from Florida MD, October 2012