Women do not like to have their breasts squeezed by equipment to get a routine mammogram. So they welcome other options like thermography. "It's just like having your picture taken," one woman explained. Using near-infrared sensitive film and computer enhancement, advocates say it is as good as x-rays and may even be better because women won't avoid having it done. So it could be useful for screening. But does it really find early breast cancer, when it can be most easily cured?
No, according to a recent study. Women who had biopsy proven early cancer then had breast thermograms done just for the study. Only half the cancers were found by thermography. And when the thermogram interpretation was "no lesions" (no abnormalities), it was correct only 77% of the time (negative predicative value).
Investigators turned up the sensitivity in the system. They could then improve the sensitivity (ability to detect lesions)—87% of the known lesions were spotted by thermography—but at the cost of generating too many "false positives." The specificity fell to less than 50%, meaning that about half the women who would have been told they had no lesions actually did.
These results were presented at a conference of breast specialists. One doctor in the audience disputed the findings, saying results in his office had a sensitivity of over 90%. But he had never published his results. He was invited to submit his data for scientific review.
Not the First Negative Study
This study was not the first to rain on thermography. Looking at five published studies that were scientifically reasonable, investigators in New Zealand found sensitivity of screening thermography to be 25% compared to routine mammography. Specificity was 74%, meaning only about three of four woman declared without lesions (normal) were without lesions.
Expert Warning
The (US) Food and Drug Administration "warned women not to substitute breast thermography for mammography to screen for breast cancer." (June 2, 2011)
Because thermography is advertised directly to women, an editorial in the December, 2011, National Review of Cancer called for regulatory action to curtail companies from misleading the public.
Expert Advice about Screening
After careful analysis of all reputable data, the United States Preventive Services Task Force states, "The USPSTF recommends biennial screening mammography [by x-ray] for women aged 50 to 74 years. ['Biennial' means every two years.]....The decision to start regular, biennial screening mammography before [emphasis added] the age of 50 years should be an individual one and take patient context into account, including the patient's values regarding specific benefits and harms. "
Mammographic screening from age 40 to 50 is controversial. The USPSTF does not recommend it because they believe the data do not support a life-saving benefit. One suggestion is to screen only women who are at high risk due to family history, or who have dense breasts. (Ravenstock et al, 2012) (However, it may take a mammogram to determine who has dense breasts).
Sources
Guilfoyle CM et al. Does infrared thermography predict the presence of malignancy in patients with suspicious radiologic breast abnormalities? American Society of Breast Surgeons 2012; Abstract 92. reported by Charles Bankhead in MedPage Today, May 7, 2012
Fitzgerald A, Berenstson-Shaw J: Thermography as a screening and diagnostic tool: a systematic review. New Zealand Medical Journal. 2012 Mar 9;125(1351):80-91.
Lovett KM, Liang BA: Risks of online advertisement of direct-to-consumer thermography for breast cancer screening. Nat Review Cancer 2011 Dec; 11 (12): 827-8
US Food and Drug Adminsitration
US Preventive Services Task Force
Van Ravesteyn NT et al. Tipping the balance of benefits and harms to favor screening mammography starting at age 40 years: A comparative modeling study of risk. Ann Intern Med 2012 May 1; 156:609.
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