Can 3D Imaging Save You From Breast Cancer?
By Karen Tran-Harding, MD
Breast cancer the most commonly diagnosed cancer in the world and is the second leading cause of cancer death in females(behind lung cancer). One out of every eight women will be diagnosed with breast cancer at some point in their lives. Unfortunately, there’s a high chance that you or someone you love will be inflicted with this illness.
That’s why it is important that we can identify cancer and treat it before it can lead to death – by preventing spread of tumor cells (metastases) throughout the body and other organs. Studies have shown that screening mammography has played a key role in reducing breast cancer deaths. When you can identify a tiny breast cancer early on, expeditious intervention will result in longer survival time.
What does a standard screening mammogram consist of?
The standard screening mammogram is a digital radiograph (or better known as an x-ray image) performed from two different angles. The issue with a standard mammogram is that it is in fact a “summation image". Think of it as converting a 3D image (your breasts) into a 2D image (your X-ray image) or turning a globe into a flat circle. There will be lots of overlap of structures. Your normal denser breast tissue or harmless calcifications can potentially “hide” or “cover up” your abnormal or cancerous tissue. Even in two different views, searching for very small lesions can be a challenge. Some younger women have very dense breasts naturally, which can make a diagnosis even more problematic.
Breast cancer screening mammograms have also been criticized for the very opposite reason. It has been argued that screening can lead to overcalling of breast cancers leading to undue stress and anxiety for the patient and excessive costs of further imaging and unnecessary biopsies.
So, an inexpensive, efficient, and simple way to screen for breast cancers was needed. Other proposed methods for screening included magnetic resonance imaging (MRI) and nuclear medicine imaging scans but these studies were cost prohibitive and time consuming to perform.
What is tomosynthesis?
Tomosynthesis is a breast imaging technology that has emerged in recent years to aid in breast cancer detection and has been gaining in popularity throughout breast imaging centers throughout the nation.
In 2011, the Food and Drug Administration (FDA) approved tomosynthesis to be used in combination with standard screening mammograms. Where mammograms are constructed from only two angles: side to side and top to bottom, tomosynthesis takes multiple x-rays in an arc and from many different angles. The result is a 3D reconstruction of your
breast rather than a 2D reconstruction – a chance to look at each layer of your breast rather than try to see through a block of it. Your real-life 3D breasts essentially can be viewed as 3D by the doctor.
It is a relatively inexpensive study as it uses an X-ray machine just like in mammography. Positioning of the breasts is also the same as it is for a mammogram and it just takes a few seconds longer to perform the 3D imaging.
Why is adding tomosynthesis to standard screening mammograms useful?
Studies have shown that tomosynthesis along with digital mammography is associated with a decrease in recall rate or, calling the patient back to the clinic for further imaging of a suspicious lesion. This is because 3D imaging offers the doctor a chance to really scrutinize the lesion and gauge if the lesion is malignant (harmful) or benign (nonthreatening) from the get go. Evidence has also shown an increase in cancer detection rate and the discovery of multiple tumors due to the decreased burden of overlapping structures. It is believed that with time, tomosynthesis will aid in decreasing breast cancer deaths as well.
What are the drawbacks to tomosynthesis?
One downside can occur when a radiologist is learning how to interpret the new imaging study – they may discover other, nonharmful lesions in the process. Just like how 3D imaging allows physicians to find more cancers, they will also be able to find more noncancerous lesions also known as “incidental findings”. However, with tomosynthesis training and experience, the radiologist will be able to differentiate between a malignant and benign lesion. Another negative is the greater time it takes for a radiologist to interpret an additional study. Tomosynthesis also costs more and increases radiation dose to the breasts than having a mammogram done alone. Although there is increased radiation, studies have demonstrated that adding tomosynthesis only increases the total radiation dose 2 times the typical mammogram dose (which is pretty low to begin with) and is still well below the limits set by the FDA.
As with every new innovation, studies are still being performed to further prove that the benefits of 3D breast imaging outweigh the risks. For now, it appears that tomosynthesis has the potential to be a great ally in the detection and fight against breast cancer. See your doctor to determine the best schedule for breast cancer screening. This will be determined by a number of considerations, including your age and risk factors.
Friedewald SM, Rafferty EA, Rose SL, Durand MA, Plecha DM, Greenberg JS, Hayes MK, Copit DS, Carlson KL, Cink TM, Barke LD, Greer LN, Miller DP, Conant EF. Breast Cancer Screening Using Tomosynthesis in Combination With Digital Mammography. JAMA. 2014;311(24):2499-2507. doi:10.1001/jama.2014.6095
Kopans DB. Digital Breast Tomosynthesis From Concept to Clinical Care. American Journal of Roentgenology 2014 202(2): 299-308
Originally from Orange County, California, Karen Tran-Harding is a radiology resident physician that found love, education, life lessons, and two corgis in the heart of the bluegrass. She has interest in medical media and education. She is a regular contributor to StantonMD and Everyday Medicine.