Breast Cancer Screening AlternativesNovember 2014
By Michael Smith, MD
Q: Are there any other options for breast cancer screening besides mammography? I am concerned about radiation exposure and I’d like to explore alternative imaging techniques.
A: Yes, there are. But doctors are still trying to figure out how to best use alternative breast imaging. So let’s take a look at your options.
More and more women are asking about mammography and radiation exposure. It turns out this is a good question to ask. Studies have shown that one mammogram exposes a woman to 0.4 mSv of radiation, the equivalent of seven weeks of background radiation from the earth and space. Let’s compare this to other imaging tests.
A chest X-ray, for instance, exposes you to 0.1 mSv of radiation. That’s the equivalent of 10 days of background radiation. A CT scan of your chest is 7 mSv, or two years of background radiation.
A CT of your abdomen is 10 mSv, or the equivalent of three years of background radiation. A CT image of your brain produces 2 mSv of radiation, or eight months outside. As you can see, a mammogram falls in the lower range of radiation exposure.1,2
But here’s the problem: A woman will get anywhere from 25 to 50 mammograms in her lifetime, whereas she’ll only get a few chest X-rays and one or two CT scans. This is important because radiation exposure is accumulative. The more radiation you’re exposed to over time, the greater the chance for DNA damage—the hallmark of all cancers.
So a lifetime of mammograms, designed to detect breast cancer, could in fact increase the risk of breast cancer later in life. Personally, I don’t like when a screening tool raises the risk of the disease that it’s trying to detect.
To date, no trial has clearly shown a link between mammography and breast cancer risk,3 however, understanding the risk of ionizing radiation tells me it’s something we should continue to investigate.
MRI—A Mammography Alternative
Let’s take a look at the first alternative—magnetic resonance imaging. MRI uses magnetic fields rather than ionizing radiation to create an image of the breast. It helps detect malignancies since it provides excellent soft tissue contrast.
Only in the last few years have clinical trial results suggested that MRI may have a role as a first-line technology for detecting breast tumors. These preliminary studies show that MRI is more sensitive at detecting invasive breast cancers than mammography.4 However, mammography is still the only imaging method that is proven to decrease mortality from breast cancer.5
Although MRI is generally considered more sensitive than mammography, it can produce false-positives. This is when MRI detects a “suspicious mass,” which often results in a biopsy that turns out not to be cancer. To be fair, this also happens with mammography.
Mammography + MRI
Currently, breast MRI is not recommended as a routine screening tool for all women. However, it is recommended for screening women who are at high risk for breast cancer, usually due to a strong family history and/or a mutation in genes such as BRCA1 or BRCA2.
Yearly mammograms plus breast MRI screening are typically recommended for women who are at higher-than-average risk of developing breast cancer—greater than the average 13% lifetime risk for all women. According to the American Cancer Society, a woman is considered high risk if she has a:
- BRCA1 or BRCA2 gene mutation,
- First-degree relative with a BRCA1 or BRCA2 gene mutation,
- Lifetime risk of breast cancer of 20% or greater, according to clinical history,
- History of radiation therapy,
- Genetic disease such as Li-Fraumeni syndrome, Cowden syndrome, or Bannayan-Riley-Ruvalcaba syndrome, or has a first-degree relative with one of them.6
If you fall into a high-risk category, there’s plenty of support for using MRI. In a study published in the New England Journal of Medicine in 2004, Dutch researchers followed 1,900 women with a risk of breast cancer greater than 15% due to genetic mutations or family history. For nearly three years, the women received yearly MRIs as well as semiannual clinical breast exams and yearly mammograms. Mammography detected 18 cancers but missed 22 that were found on MRI. MRI found 32 cancers and missed only eight that showed up on mammograms.7
An Italian study showed similar results for a comparable group of high-risk women. In that study, 278 women were given annual clinical breast exams, mammograms, MRIs, and ultrasounds. In the first two years, 18 cancers were found—17 showed up on MRI, including six that all other methods had missed.8
A third study, completed at six US medical centers, compared MRI, mammography, and ultrasound in 171 women over age 25 whose lifetime risk of developing breast cancer was very high (20% or more).
Sixteen biopsies were performed and six cancers were diagnosed; MRI detected all six, mammography only two, and ultrasound only one. Neither mammography nor ultrasound found any tumors that MRI missed.9
So here’s what we know: MRI does not use ionizing radiation; it’s established as an effective screening tool for high-risk patients; and it’s more sensitive at detecting breast cancer than mammography. So why isn’t it considered for first-line screening?
One answer goes back to those “false positives.” Breast MRI is sensitive for detecting cancers but not specific for cancers. This means that it can’t always tell the difference between a benign and malignant mass. The biggest impediment, however, may be that an MRI costs much more than a mammogram. We checked prices locally in South Florida and found the average out-of-pocket expense for a mammogram is $125, whereas the average price for a breast MRI is $760. Some insurance companies pay for mammograms, but not for an MRI when used as a primary screening tool.
Ultrasound And More
A second option is breast ultrasound. Unlike mammography, which has low sensitivity in detecting breast cancer in young women,9 ultrasound is primarily used in younger women with dense breast tissue.10 However, it hasn’t been shown to be sensitive enough as a stand-alone screening tool.
Gaining in popularity is a third option called thermography. It detects changes in surface temperatures associated with breast abnormalities. Unfortunately, it has a low sensitivity for detecting breast cancer.11
Standard mammograms use two beams of radiation to identify suspicious lesions. These are called 2D mammograms.
Newer mammograms are using three beams of radiation and pick up more lesions while reducing the “false positive” rate. Performed with digital mammography using the same scanner, 3D mammography (breast tomosynthesis) takes multiple images and reconstructs them to create a 3D view of the entire breast. These 3D devices may emit more radiation and they cost an average of $200 compared to the standard 2D price of $125.
What I Suggest
So what does all of this mean? We definitely want to minimize our exposure to ionizing radiation. Yet, breast cancer screening is still the best-known preventative strategy we can offer.
It’s clear that women at high risk of breast cancer should utilize a combination of mammography and MRI. This will provide the highest sensitivity for detecting suspicious masses and the highest specificity for avoiding false positives.
Young women with dense breast tissue should be screened using ultrasound, with MRI as a secondary screening tool if suspicious masses are identified. Mammography is a poor screening tool for dense breasts, leaving ultrasound and MRI as the best weapons for early detection in this population of women.
But what about women at average risk who have breast tissue that’s normal density? Well, the verdict is still out. More sensitivity and specificity research is needed utilizing MRI.
Interestingly, preliminary reports using dynamic MRI imaging (a method that allows analysis of blood vessels generated by a tumor) show promise for improving MRI as an initial screening tool for all women. But we can’t draw any definite conclusions at this time.
So here’s what I suggest for women concerned about radiation exposure: If you’re at average risk for breast cancer and your breast tissue is normal density, use MRI as an initial screening tool. If a suspicious mass is identified, then use mammography to verify the mass. This way you’ll only exposure yourself to ionizing radiation if it’s absolutely necessary.
Is what I am suggesting feasible? Clinically speaking, yes it is. But is what I suggest cost effective enough to be covered by insurance companies? Well, that’s something for you to discuss with your insurance carrier.
Dr. Smith, a graduate of the University of Texas Southwestern Medical School, is senior health scientist and online personality for Life Extension®. Often described as “the country doctor with a city education,” Dr. Smith is an author, blogger, and lecturer who has created and conducted numerous health-related webinars, as well as scripted and hosted a variety of informative online videos.
If you have any questions on the scientific content of this article, please call a Life Extension®Health Advisor at 1-866-864-3027.
- Available at: http://www.radiologyinfo.org/en/safety/?pg=sfty_xray. Accessed August 17, 2014.
- Available at: http://www.ans.org/pi/resources/dosechart/. Accessed August 19, 2014.
- Giannakeas V, Lubinski J, Gronwald J, et al. Mammography screening and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers: a prospective study. Breast Cancer Res Treat. 2014 Aug;147(1):113-8.
- Heywang-Köbrunner SH, Hacker A, Sedlacek S. Magnetic resonance imaging: the evolution of breast imaging. Breast. 2013 Aug;22 Suppl 2:S77-82.
- Morrow M, Waters J, Morris E. MRI for breast cancer screening, diagnosis, and treatment. Lancet. 2011;378:1804-11.
- Available at: http://www.cancer.org/cancer/breastcancer/moreinformation/breastcancerearlydetection/breast-cancer-early-detection-acs-recs . Accessed August 19, 2014.
- Kriege M, Brekelmans CT, Boetes C, et al. Efficacy of MRI and mammography for breast-cancer screening in women with a familial or genetic predisposition. N Engl J Med. 2004 Jul 29;351(5):427-37.
- Sardanelli F, Podo F, D’Agnolo G, et al. Multicenter comparative multimodality surveillance of women at genetic-familial high risk for breast cancer (HIBCRIT study): interim results. Radiology. 2007 Mar;242(3):698-715.
- Lehman CD, Isaacs C, Schnall MD, et al. Cancer yield of mammography, MR, and US in high-risk women: prospective multi-institution breast cancer screening study. Radiology. 2007 Aug;244(2):381-8.
- Devolli-Disha E, Manxhuka-Kërliu S, Ymeri H, Kutllovci A. Comparative accuracy of mammography and ultrasound in women with breast symptoms according to age and breast density. Bosn J Basic Med Sci. 2009 May;9(2):131-6.
- Kontos M, Wilson R, Fentiman I. Digital infrared thermal imaging (DITI) of breast lesions: sensitivity and specificity of detection of primary breast cancers. Clin Radiol. 2011 Jun;66(6):536-9.