Dr. Ron’s Research Review – June 22, 2011

This week’s research review focuses on thermography.

Systematic reviews have shown that for every 2000 women invited for mammography screening throughout 10 years, only 1 will have her life prolonged; 10 healthy women will be over-diagnosed with breast cancer and will be treated unnecessarily; and more than 200 women will experience substantial psychosocial distress for months because of false-positive findings. Regular breast self-examination does not reduce breast cancer mortality, but doubles the number of biopsies, and it therefore cannot be recommended. (Brodersen, Jorgensen et al. 2010)

Overall, 14.6% of women in the intervention arm and 18.1% of women attending at least one routine screen experienced one or more false-positive screen during the trial. The rates of false-positive mammography at first and subsequent routine screens were 4.9% and 3.2%, respectively. The cumulative false-positive rate over seven screens was 20.5%. (Johns and Moss 2010)

For every breast cancer death averted, even in the age group for which screening is least controversial (ages 50 to 70 years), 838 women must undergo screening for six years, generating thousands of screens, hundreds of biopsies, and many cancers treated as if they were life-threatening when they are not. (Esserman, Shieh et al. 2009)

Of 9747 screening mammograms, 6.5% were false-positive; 23.8% of women experienced at least one false-positive result. After nine mammograms, the risk of a false-positive mammogram was 43.1%. (Christiansen, Wang et al. 2000)

Thermography

No single tool provides excellent predictability; however, a combination that incorporates thermography may boost both sensitivity and specificity. (Kennedy, Lee et al. 2009)

Thermography had 90 true-negative, 16 false-positive, 15 false-negative and 5 true-positive results. The sensitivity was 25%, specificity 85%, positive predictive value 24%, and negative predictive value 86%. (Kontos, Wilson et al. 2011)

Dr. Ron

Articles

Amalu 2002 - A Review of Breast Thermography

         International Academy of Clinical Thermography

         Download

The benefits and harms of screening for cancer with a focus on breast screening

            (Brodersen, Jorgensen et al. 2010) Download

The balance between benefits and harms is delicate for cancer screening programs. By attending screening with mammography some women will avoid dying from breast cancer or receive less aggressive treatment. But many more women will be overdiagnosed, receive needless treatment, have a false-positive result, or live more years as a patient with breast cancer. Systematic reviews of the randomized trials have shown that for every 2000 women invited for mammography screening throughout 10 years, only 1 will have her life prolonged. In addition, 10 healthy women will be overdiagnosed with breast cancer and will be treated unnecessarily. Furthermore, more than 200 women will experience substantial psychosocial distress for months because of false-positive findings. Regular breast self-examination does not reduce breast cancer mortality, but doubles the number of biopsies, and it therefore cannot be recommended. The effects of routine clinical breast examination are unknown, but considering the results of the breast self-examination trials, it is likely that it is harmful. The effects of screening for breast cancer with thermography, ultrasound or magnetic resonance imaging are unknown. It is not clear whether screening with mammography does more good than harm. Women invited to screening should be informed according to the best available evidence, data should be reported in absolute numbers, and benefits and harms should be reported using the same denominator so that they can be readily compared.

Predicting the cumulative risk of false-positive mammograms

            (Christiansen, Wang et al. 2000) Download

BACKGROUND: The cumulative risk of a false-positive mammogram can be substantial. We studied which variables affect the chance of a false-positive mammogram and estimated cumulative risks over nine sequential mammograms. METHODS: We used medical records of 2227 randomly selected women who were 40-69 years of age on July 1, 1983, and had at least one screening mammogram. We used a Bayesian discrete hazard regression model developed for this study to test the effect of patient and radiologic variables on a first false-positive screening and to calculate cumulative risks of a false-positive mammogram. RESULTS: Of 9747 screening mammograms, 6. 5% were false-positive; 23.8% of women experienced at least one false-positive result. After nine mammograms, the risk of a false-positive mammogram was 43.1% (95% confidence interval [CI] = 36.6%-53.6%). Risk ratios decreased with increasing age and increased with number of breast biopsies, family history of breast cancer, estrogen use, time between screenings, no comparison with previous mammograms, and the radiologist's tendency to call mammograms abnormal. For a woman with highest-risk variables, the estimated risk for a false-positive mammogram at the first and by the ninth mammogram was 98.1% (95% CI = 69.3%-100%) and 100% (95% CI = 99.9%-100%), respectively. A woman with lowest-risk variables had estimated risks of 0.7% (95% CI = 0.2%-1.9%) and 4.6% (95% CI = 1. 1%-12.5%), respectively. CONCLUSIONS: The cumulative risk of a false-positive mammogram over time varies substantially, depending on a woman's own risk profile and on several factors related to radiologic screening. By the ninth mammogram, the risk can be as low as 5% for women with low-risk variables and as high as 100% for women with multiple high-risk factors.

False-positive results in the randomized controlled trial of mammographic screening from age 40 ("Age" trial)

            (Johns and Moss 2010) Download

BACKGROUND: False-positive recall is a recognized disadvantage of mammographic breast screening, and the rate of such recalls may be higher in younger women, potentially limiting the value of screening below age 50. METHODS: Attendance and screening outcome data for 53,884 women in the intervention arm of the U.K. Age trial were analyzed to report observed false-positive recall rates during 13 years of trial fieldwork. The Age trial was a randomized controlled trial of the effect of mammographic screening from age 40 on breast cancer mortality, conducted in 23 National Health Service screening centers between 1991 and 2004. Women randomized to the intervention arm were offered annual invitation to mammography from age 40 or 41 to age 48. RESULTS: Overall, 7,893 women (14.6% of women the intervention arm and 18.1% of women attending at least one routine screen) experienced one or more false-positive screen during the trial. The rates of false-positive mammography at first and subsequent routine screens were 4.9% and 3.2%, respectively. The cumulative false-positive rate over seven screens was 20.5%. Eighty-nine percent of women who had a false-positive recall at their previous screen attended their next invitation to routine screening. CONCLUSIONS: The rates of false-positive recall in the Age trial were comparable with the national screening program; however, the positive predictive value of referral was lower. Experiencing a false-positive screen did not seem to lessen the likelihood of re-attendance in the trial. IMPACT: The question of greatly increased false-positive rates in this age group and of their compromising re-attendance is refuted by the findings of this study.

A comparative review of thermography as a breast cancer screening technique

            (Kennedy, Lee et al. 2009) Download

Breast cancer is the most frequently diagnosed cancer of women in North America. Despite advances in treatment that have reduced mortality, breast cancer remains the second leading cause of cancer induced death. Several well established tools are used to screen for breast cancer including clinical breast exams, mammograms, and ultrasound. Thermography was first introduced as a screening tool in 1956 and was initially well accepted. However, after a 1977 study found thermography to lag behind other screening tools, the medical community lost interest in this diagnostic approach. This review discusses each screening tool with a focus brought to thermography. No single tool provides excellent predictability; however, a combination that incorporates thermography may boost both sensitivity and specificity. In light of technological advances and maturation of the thermographic industry, additional research is required to confirm the potential of this technology to provide an effective non-invasive, low risk adjunctive tool for the early detection of breast cancer.

Digital infrared thermal imaging (DITI) of breast lesions: sensitivity and specificity of detection of primary breast cancers

            (Kontos, Wilson et al. 2011) Download

AIM: To determine the sensitivity and specificity of digital infrared thermal imaging (DITI) in a series of women who underwent surgical excision or core biopsy of benign and malignant breast lesions presenting through the symptomatic clinic. MATERIALS AND METHODS: DITI was evaluated in 63 symptomatic patients attending a one-stop diagnostic breast clinic. RESULTS: Thermography had 90 true-negative, 16 false-positive, 15 false-negative and 5 true-positive results. The sensitivity was 25%, specificity 85%, positive predictive value 24%, and negative predictive value 86%. CONCLUSION: Despite being non-invasive and painless, because of the low sensitivity for breast cancer, DITI is not indicated for the primary evaluation of symptomatic patients nor should it be used on a routine basis as a screening test for breast cancer.

Emerging controversies in breast imaging: is there a place for thermography?

            (Plotnikoff and Carolyn 2009) Download


References

Brodersen, J., K. J. Jorgensen, et al. (2010). "The benefits and harms of screening for cancer with a focus on breast screening." Pol Arch Med Wewn 120(3): 89-94.

Christiansen, C. L., F. Wang, et al. (2000). "Predicting the cumulative risk of false-positive mammograms." J Natl Cancer Inst 92(20): 1657-66.

Esserman, L., Y. Shieh, et al. (2009). "Rethinking screening for breast cancer and prostate cancer." JAMA 302(15): 1685-92.

Johns, L. E. and S. M. Moss (2010). "False-positive results in the randomized controlled trial of mammographic screening from age 40 ("Age" trial)." Cancer Epidemiol Biomarkers Prev 19(11): 2758-64.