Breast Cancer Detection: An Expanding Array of Approaches
October is Breast Cancer Awareness Month. Fortunately for us we have all become more aware of breast cancer partly because each and every one of us is personally affected by this disease that affects one in eight American women. Whether it be our sisters, neighbors, mothers, friends or colleagues we have all seen the impact breast cancer has on the individual and their family. However, we have all also seen the triumphs of breast cancer.
It is important to remember that with early detection, breast cancer is truly a curable disease with an ever improving rate of survival. This improvement in survival is due to both early detection and improved individualized therapy.
Today we are moving into an era of individualized imaging to optimally diagnose breast cancer in women of different ages, risk factors and breast densities. Just as everyone with breast cancer is not treated with one medicinal regimen, we are rapidly moving into a phase of individualized early detection to answer the needs of different women. Once again, there is certainly not a case of “one size fits all” and the result of this rapidly advancing field of individualized screening and imaging will likely result in further improvements in survival as a consequence of earlier, more curable detection of breast cancer.
Mammography unquestionably remains the mainstay for breast cancer detection and definitely results in a reduction in death rate from breast cancer of up to 44%. Yet mammography is an imperfect examination. Fifteen percent of breast cancer is not visible on mammograms and in women with dense breasts up to 35% of breast cancer cannot be seen on a mammogram. This is a particularly difficult quandary since increased breast density is a strong independent risk factor for developing breast cancer. Although mammography has significantly impacted mortality from breast cancer, we certainly need additional approaches to breast cancer detection to allow for the detection of more, earlier, curable breast cancers.
Mammography, and the second most common approach to imaging breast cancer, ultrasound, are based on anatomic appearance of disease versus normal breast tissue and asks the question, “How does breast cancer look?” However, our arsenal of imaging modalities now extends far beyond mammography and ultrasound. For women who are at significantly increased risk, such as women who have the BRCA1 or 2 genes, new approaches asking fundamentally different questions are implemented. The question of how breast cancer functions differently from the surrounding normal breast tissue is asked. Magnetic Resonance Imaging (MRI) has been used for over 10 years and has resulted in improved breast cancer detection in this population of women. We now know that MRI can detect additional areas of breast cancer in 10% of women with newly diagnosed breast cancer. This significantly changes how they are treated and detects unsuspected breast cancer in women at increased risk who have normal mammograms and physical examination.
There are limitations to MRI as well, most notably false positives; areas which are in fact normal healthy breast tissue, may appear similar to cancer, and may result in additional biopsies or follow up with the accompanying anxiety. Furthermore, an ever increasing number of women cannot undergo MRI for various reasons including pacemakers, physique or kidney problems. We now have an exciting new molecular imaging approach to detecting breast cancer called Breast Specific Gamma Imaging or BSGI. BSGI is comparable to MRI in detecting breast cancer with fewer false positives and all women can undergo BSGI. Although associated with a small dose of radiation, which MRI does not have, BSGI has been shown to be a very effective and exciting modality to diagnose breast cancer in women at increased risk for cancer as well as additional areas of breast cancer in women with newly diagnosed cancer. It is also a far easier test for the patient as it is performed comfortably seated while the patient can read or watch a video without the issues of being in an enclosed space. In fact, data suggests that with the rather infrequent, but difficult to detect, invasive lobular cancer, BSGI may have advantages in detection as compared to MRI. Although younger and with less data in the literature, BSGI is increasingly being integrated into breast imaging practices for the benefit of the patient.
What about the situation of women with dense breasts, where mammography is more limited, but who are not at sufficiently increased risk to be screened with MRI or BSGI? There is an ongoing trial looking at exactly this population of women with automated whole breast ultrasound to see how many additional cancers will be detected with the use of a technology that is painless, quick, and cost effective and uses no ionizing radiation. Although the study is currently ongoing and will ultimately accrue more than 20,000 women, preliminary data is very exciting and demonstrates a significant increase in breast cancer detection in this population of women.
As you can see, we have an ever expanding array of approaches to optimally detect breast cancer using different approaches for women with different breast densities and with varying individual risk factors of breast cancer. With time, and additional research, we will undoubtedly continue to move towards more individualized imaging and diagnosis of breast cancer for the goal of diagnosing all breast cancer in their early curable stages.
Editor’s Note: The Prevent Cancer Foundation’s October guest blogger Rachel F. Brem, M.D. is the Director, Breast Imaging and Interventional Center, Professor of Radiology and Vice Chair, Research and Faculty Development at the George Washington University Medical Center.