By Kirsten West ND, LAc
The utility of Mammography continues to be a hotly debated subject. In fact, many women are opting out of its use as a breast screening tool and employing alternative testing such as thermography, ultrasounds and/or MRIs, when possible.
The touted issue with mammograms is this: while their sensitivity is high their specificity remains questionable. This is likely confusing for most. Sensitivity describes how well the screening test elucidates who truly has disease. Specificity, is the opposite, it demonstrates who truly does not have the disease. Therefore, mammograms are able to accurately predict about 84% of those women who have cancer which leads to a high “sensitivity” rating.[i] However, because the specificity is low, mammograms often lead to several false positives. [ii] The latter is an issue.
False positives lead to not only the need for follow-up testing, continued exposure to radiation, biopsies (for those areas most suspicious) but also, and in many cases, unnecessary fear and worry. More often than not, once a woman has a mammogram that is “normal” but with findings that require follow-up, she will end up on the mammogram “bandwagon” – continued screening is typically recommended every 6 months. This is due to the fact that the more mammograms a woman has the more tendency there will be for a false positive result. (Again, mammogram results are sensitive but NOT specific.) Most women with a false positive result, do not have breast cancer. Not only is this continued radiation exposure but also compression and smashing of breast tissue. If false positive appears suspicious enough, a biopsy may be taken.[iii] These repeat mammograms and biopsies may actually place women at a greater risk for developing cancer.
The utility of screening mammograms is further compounded by those women with dense breasts. Fibrocystic, fibrous and cystic breasts make this specificity even lower.[iv] In fact, it is can be recommended that women with fibrocystic breast tissue avoid mammograms all together. If there is a family history of cancer or reason to suspect concern, MRIs are typically the best way to go in these situations. The issue here, insurance oftentimes, does not cover as mammograms are the standard of screening practice.
The current guidelines by the American Cancer Society do continue to strongly recommend that women with an average risk of breast cancer undergo regular screening with mammography starting at the age of 45yo. In addition, it is recommended that screening should occur annually from the ages of 45 to 54yo. At the age of 55yo it is recommended that women transition to biennial screening however, should they elect to pursue annual screening, this remains a possibility. [v]
Recently, these guidelines have been questioned. In fact, a meta-analysis (a study that seeks to compare multiple studies and gather data on given subject) sought out to determine just how affective breast cancer screening is with the use of mammography.[vi] This study concluded that although breast cancer mortality is generally reduced with mammography screening, the results were not statistically significant for all ages. In fact, screening seemed to make the greatest difference for those women aged 50 years or older. It is also notable that women who are 50 years or older tend to have less fibrous/dense breasts. These findings seem to question the current ACS guidelines.
Unfortunately, most insurance plans will not cover alternate diagnostic screening for breast cancer. The gold standard, in regards to sensitivity and specificity, is a MRI. A MRI is of great utility for young women with fibrous and dense breasts. Thermograms are also an option, however, these do require a baseline followed by continued imaging anywhere from 3 to 6 months or annually depending on the findings. An ultrasound may also be utilized and is helpful in detecting cystic and fluid filled irregularities but it cannot determine if a mass is cancerous. Obviously, more options and specifically, one that could take the place of screening mammograms, is needed.
Recently and importantly, a new screening technology has gained attention. In fact, this is a diagnostic screening method which has worked well for the screening of prostate cancer. The method is called: Dynamic Contrast Specific Ultrasound Tomography (DCSU/T). The way in which this testing works is pretty phenomenal and also makes sense from a physiological point of view.
It is well known that blood vessels within cancers tend to be chaotic. Researchers have discovered that by injecting microbubbles into the blood stream, these bubbles can be detected with an echoscanner, making chaotic blood vessel formations discernible. This has worked well for prostate cancer detection. However, this method had not been suitable for breast cancer because the breast itself has its own excessive movement and therefore, localization of the bubbles has not been possible.
Scientists have now discovered that by using the sound emitted from the echoscanner, the vibration of the microbubbles can be detected. Additionally, by using a phenomenon known as the “second harmonic” they now understand that the more bubbles that are encountered by the sound in their route- the bigger vibrational delay compared to the original sound. This difference in vibration can only be captured on the opposite side of the medium being tested (in this case the breast) which makes this technology perfect for breast screening.
While this method is not currently available, preclinical studies are beginning. It has also been postulated that this technology will not act as a stand-alone treatment but one that with be used in a combination with other innovative technologies- all without the use of radiation. For more information on this technology please check out this article; Breast-Friendly, Radiation-Free Alternative to Mammogram in the Making.
And if you want to stay abreast (literally and figuratively) regarding implementation of DCSU/T, follow the Eindhoven University of Technology website.
Belgium is proving a frontrunner in this advanced screening technology. Perhaps this is a Nordic tradition we should all adopt.
References:
[i] Breast Cancer Surveillance Consortium (BCSC). Performance measures for 1,838,372 screening mammography examinations from 2004 to 2008 by age — based on BCSC data through 2009. National Cancer Institute. http://breastscreening.cancer.gov/data/performance/screening/2009/perf_age.html, 2013.
[ii] Elmore JG, Barton MB, Moceri VM, et al. Ten-year risk of false positive screening mammograms and clinical breast examinations. N Engl J Med. 338: 1089-96, 1998.
Hubbard RA, Kerlikowske K, Flowers CI, Yankaskas BC, Zhu W, Miglioretti DL. Cumulative probability of false-positive recall or biopsy recommendation after 10 years of screening mammography: a cohort study. Ann Intern Med. 155(8):481-92, 2011.
Independent UK Panel on Breast Cancer Screening. The benefits and harms of breast cancer screening: an independent review. Lancet. 380(9855):1778-86, 2012.
[iii] Raftery J, Chorozoglou M. Possible net harms of breast cancer screening: updated modelling of Forrest report. BMJ. 2011; 343: d7627.
[iv] Siu AL on behalf of the U.S. Preventive Services Task Force. Screening for breast cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 164(4):279-96, 2016.
[v] National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Breast cancer screening and diagnosis, Version 1.2015. http://www.nccn.org, 2015.
[vi] Nelson H, Fu R, Cantor A, Pappas M, Daeges M, and Humphrey L. Effectiveness of Breast Cancer Screening: Systemic Review and Meta-analysis to Update the 2009 U.S. Preventative Services Task Force Recommendation. Annals of Internal Medicine. Ann Intern Med. 2016 Feb 16;164(4):244-55. doi: 10.7326/M15-0969. Epub 2016 Jan 12.
