Case Study by Dr. LeRoySerial infrared thermography in the identification of invasive breast cancer in a 55 year-old woman.
Nicholas R. LeRoy, DC, MS
AbstractObjective: The purpose of this case study was to demonstrate the clinical use of infrared breast thermography in a serial, diagnostic fashion. Thermographic interpretation guidelines have been developed that do not account for serial imaging changes, but rather attempt to provide guidance in the interpretation of stand-alone infrared breast images. This case study also demonstrates the use of thermography in identifying a thermovascular abnormality in a 55 year old patient that resulted in the diagnosis of invasive intraductal carcinoma of the breast. Design: A 55 year old woman was screened with infrared thermography on two occasions: a baseline and a 7-month follow-up. Location: A private, holistic medical clinic. Subject: A healthy, 55 year old woman with no history of cancer. Results: A 1.02 degree centigrade increase in temperature was identified in the right superior breast when serial thermographic interpretation was performed. This isolated thermovascular findings prompted additional testing that yielded a diagnosis of invasive intraductal carcinoma. Conclusion: Serial infrared breast screening may provide a useful tool in the detection of breast cancer.
IntroductionInfrared breast thermography is based upon the observation that malignant breast tumors emit greater heat than healthy breast tissue. Hippocrates was one of the first to make this observation, immersing patients in mud to observe the pattern of drying, declaring that the area which dried first was diseased.1 Twenty-five hundred years later the first medical breast thermogram was published in 1956 by Ray Lawson, initiating a significant amount of interest in infrared breast thermography in the decades that followed.2-4
Although the finding that breast tumors give off more heat was initially thought to be caused by an increase in the metabolism of malignant cells, it is now known that premalignant and malignant cells secrete vasoactive substances that increase blood perfusion by causing vasodilation and angiogenesis.5,6 Nitric oxide and vascular endothelial growth factor are two substances secreted by tumors to accomplish this effect.7,8 Infrared thermography identifies and characterizes these vascular alterations.
All objects with a temperature above absolute zero emit infrared radiation that is proportional to their temperature. Capturing the emissions within the proper wavelengths given off by humans, allows for a quantitative measure of the temperature. It is this quantification of infrared emissions from the breast that allows a thermographer to determine whether a thermogram is abnormal and the likelihood that malignancy is present. In attempt to achieve consistency in thermal interpretation, as well as to maximize inter-examiner reliability, interpretation guidelines for breast thermography have been created.
Gautherie was one of the first thermographic researchers to develop such guidelines. In the early 1980s he devised a two-part assessment protocol relying on qualitative and quantitative criteria.9 Each part consists of ten thermal evaluations with a corresponding numerical risk associated with each. Qualitatively, a thermographer characterizes the vasculature present, looking for a departure from normal curvilinear vessels, symmetry, as well as larger areas of hyperthermia and/or hypothermia. An "anarchic", or highly disorganized vascular pattern carries a higher risk than a simple network of vessels. Likewise, a hyperthermic area carries higher risk, and thus score, than a hypothermic area. Quantitative assessment depends upon the ability to determine the temperature of a vessel or area as compared to a cooler area of the ipsilateral and contralateral breast. The selection of an area to be evaluated is accomplished with interpretation software. The temperature difference between two selected points, or "delta T", is calculated and a numerical score relating to the likelihood of pathology being present is assigned. The overall score is then summated from all twenty criteria and a "Thermal Class" (Th Class) ranging from I (low risk of pathology) to V (high risk of pathology) is defined for each breast. Under this risk classification system a clinician can then, by taking into account historical, physical, and other completed diagnostic studies, make a recommendation to the patient that may include additional diagnostic studies.
Aside from not exposing a woman to potentially cancer causing ionizing radiation, the identification of vascular phenomena that are a hallmark of malignancy is perhaps the greatest value of infrared studies of the breast. These vascular changes associated with cancer are thought to occur very early in malignancy, possibly occurring while still in a pre-malignancy state. In 1980, Gros and his associates screened over 55,000 women, following 1,527 patients with initially healthy breasts and abnormal thermograms for 12 years. Forty percent of these women developed breast cancer within 5 years. The authors concluded that "an abnormal thermogram is the single most important marker of high risk for the future development of breast cancer".10 Although researchers have found that a persistently abnormal thermogram is strongly correlated with the development of breast cancer, there are substantially more studies that support a role of thermography in breast cancer detection.
Spitalier and associates used thermography to screen 61,000 women over a 10 year period. They found that 91% of non-palpable cancers were detected by infrared imaging and that of all the patients with cancer, thermography was the first indicator of the disease in 60% of the cases.11 Thomassin et al. studied 130 confirmed breast cancers that ranged from 3-5 mm. Of these cancers, 10% were detected by mammography alone, 50% by thermography alone, and 40% by both techniques. Thus, there was a thermal abnormality in 90% of the patients and the only sign of cancer in 50% of the cases.12
In a simple review of over 15 large-scale studies from 1967 to 1998, infrared imaging of the breast has demonstrated an average sensitivity and specificity of 90%.13
With the amount of research supporting the use of infrared thermography, it seems odd that mainstream medicine hasn't embraced this innovative technology. Most clinicians have not heard of it, and those who have dismiss it, claiming thermography is inaccurate. This misconception is the result of the Breast Cancer Detection and Demonstration Project (BCDDP), the most frequently quoted reason for the limited use of thermography. The BCDDP was an ACS- and NCI-funded study that ran from 1973 to 1979 and collected data from many centers in the U.S. Its goal was to evaluate physical examination, mammography and infrared thermography.14
From the BCDDP's inception, there were significant flaws in the study design with respect to thermography. While the mammographic protocol was extensive and described in great detail, the entire protocol for thermography was outlined in one paragraph. The study required all mammographic centers to be trained and have expertise in mammography. The opposite was true for the thermography guidelines, where no training was required. In fact, only 5 out of 27 demonstration project centers had any expertise in infrared imaging and interpretation.15
Due to the numerous flaws in study design and quality control, the initial thermographic results were disappointing and thermography was dropped from further evaluation by the BCDDP. Consequently, mammography was found to be a useful screening tool and became the standard-of-care in breast cancer screening. Thermographic research continued into the early 1980s; however, as radiology centers implemented mammographic equipment and technicians and radiologists became trained in mammography, interest in thermography waned. In the late 1980s, holistic and alternative practitioners, searching for safe alternatives to ionizing radiation as well as tests that provided information regarding physiologic function as opposed to anatomy, embraced thermographic technology. This phenomenon, however, was likely to the detriment of thermography in general, alienating the medical community from using this useful tool that became seen as an "alternative medicine" test that lacked accuracy.
The purpose of this case study is not to attempt to reproduce the numerous studies that have identified breast thermography as a safe, effective adjunct to screening mammography, but to demonstrate its use in a small, holistic private practice. The majority of infrared research relating to the breast was performed in the 1970s and early 1980s. There has been very little research published since, probably owing to the adoption of mammography as the gold standard in breast cancer screening in the 1980s. It is this author's hope that interest in this useful breast cancer screening tool will be rekindled.
Materials and MethodsThis case study consisted of using serial digital infrared breast thermography on a healthy 55 year old woman who lacked previous infrared breast screening. A screening mammogram had last been performed approximately 4 years prior to the initial infrared screening and was unremarkable. She had not had any mammograms since because of her worry that mammography could cause breast cancer. She had two biopsies performed five and seven years prior in the right and left breast, respectively, that were assessed as benign. At the time of the initial screening, examination revealed a right breast mass measuring 3 cm by 5 cm at the 11 o'clock position in the right breast, and a left breast mass measuring 1 cm by 2 cm at the 4 o'clock position. At the time of the follow-up screening, approximately seven months later, both masses remained unchanged.
On both screening occasions the patient was allowed to equilibrate to the ambient room temperature of 72 degrees Fahrenheit for twenty minutes, disrobed from the waist upward. Her arms were positioned away from the lateral breasts to minimize artifact.
Digital images using an Infrared Solutions Flex Cam T infrared camera were obtained. Anteroposterior images and right and left oblique images were performed and imported to Infrasoft clinical infrared interpretive software for analysis.
Results:Initial infrared screening revealed a hyperthermic area in the right breast, superomedial and superolateral to the areolar complex that also included the areolar complex (see figure 1). This hyperthermic area (arrow 1) was 2.04 degrees centigrade higher than the coldest area in the lower, medial left breast (arrow 2). The left breast was unremarkable with limited thermovascular findings. The resulting thermal class was Th2 and Th1 for the right and left breasts, respectively, indicating low risk of breast disease.
Figure 1Arrow 1 demonstrates a hyperthermic area in the right breast superior to the areola. Arrow 2 identifies the coldest area in the left breast. The Delta T (the temperature difference between arrows one and two) is 2.04 degrees centigrade. The follow-up thermal imaging performed seven months later revealed a similar thermovascular pattern in both breasts. However, the hyperthermic area in the right breast appeared slightly larger and more distinct (see figure 2).
Figure 2This hyperthermic area (arrow 1) was now 3.06 degrees centigrade higher than the coldest area in the lower, medial left breast (arrow 2). There was, therefore, a 1.02 degree centigrade increase in the hyperthermic area of the upper right breast when the second screening was compared to the initial screening. Despite the changes noted, the resulting thermal class was unchanged for both breasts, indicating low risk of breast disease. Based on the relative increase in the temperature of the hyperthermic area in the right upper breast, a diagnostic mammogram was performed that identified two suspicious lesions in the right breast, one anteriorly at the 11 to 12:00 position and the second, posteriorly at the 11 to 12:00 position. Ultrasound core biopsies were performed, which identified moderately differentiated infiltrating ductal carcinoma in both lesions of the right breast. The patient underwent a right mastectomy and lymph node dissection. All six lymph nodes sampled were negative for metastatic tumor.
Discussion:This case study demonstrated the use of screening breast thermography in a clinical setting. The patient, a 55 year-old woman with no prior history of malignancy, opted to forego screening mammography due to her concerns with the risk of ionizing radiation. She instead chose to use thermography based on information she had obtained, primarily via the internet. Her initial thermogram was interpreted as low risk for breast pathology using existing interpretive guidelines. Although the patient's follow-up imaging performed seven months later was likewise assessed as low risk, there was nonetheless an isolated thermal change that created a sufficient level of clinical suspicion to warrant additional testing. In this case, further testing did in fact result in the diagnosis of invasive ductal cancer in the area of suspicion.
It would seem reasonable to question the validity of the interpretation guidelines described in this case. The patient very likely had invasive ductal carcinoma at the time of the first screening, and yet scored low in the thermal risk classification (Th2). However, research performed on thousands of women in the 1980s utilizing the described classification system has demonstrated its usefulness in describing thermovascular findings that correlated well with breast cancer. But like any screening tool, including mammography, false-negatives do occur. This case study may have fallen into the false-negative category, underscoring the need to base clinical judgment not entirely on a single set of diagnostic criteria.
Thermovascular findings in the breast should not change over time; they are, in effect, fingerprints of the breast. Although increases and decreases in the temperature of specific vessels and areas are not unusual, they should be global in nature. The increased temperature on serial imaging of a single hyperthermic area in the patient's right breast was the key finding that led to additional testing. This author's search of thermographic literature was unable to locate any research that described the use of serial monitoring in this fashion.
Although mammography has been the gold-standard in breast cancer screening for over two decades, the patient's apprehension regarding mammography is not without merit. It is outside the scope of this study to attempt an indictment of mammography on the grounds that it is hazardous; but a discussion of the patients concern is apropos and serves to highlight possible advantages to the use of thermography over mammography.
It is common knowledge that ionizing radiation contributes to cancer. Despite this fact, proponents of screening mammography downplay the risk, claiming that the total radiation exposure is low. However, for decades research has clarified the risk and continues to do so. A 2009 study in the Journal of the National Cancer Institute estimated the risk of radiation-induced breast cancer from mammographic screening for young BRCA mutation carriers. The researchers found "that there would be no net benefit from annual mammographic screening of BRCA mutation carriers at age 25-29 years; the net benefit would be zero or small at age 30-34 years".16 To put it simply, in women under the age of 35 years with the BRCA mutation, the risk of radiation-induced breast cancer from annual mammography would exceed the benefit of early diagnosis. A study by Frankenberg-Schwager et al. tested the mutagenicity of mammography x-rays and were likewise concerned, stating that "one should be cautious and avoid early and frequent mammography exposure of predisposed women".17
With regard to the concept of a "safe, low dose" of radiation, Brenner et al. cited that "the very low energy x-rays used in screening mammography (26-30 kVp) are expected to be more hazardous, per unit dose, than high-energy x- or gamma-rays, such as those to which A-bomb survivors (from which radiation risk estimates are derived) were exposed. Based on in vitro studies using oncogenic transformation and chromosome aberration end-points, as well as theoretical estimates, it seems likely that low doses of low-energy x-rays produce an increased risk per unit dose (compared with high energy photons) of about a factor of 2".18
A comprehensive review of the risk of breast cancer due to screening mammograms exceeds the scope of this case study. Suffice it to say that there appears to be legitimate concern regarding the risk of mammography. The patient, however, may be representative of a population of women avoiding mammograms because of these concerns. As clinicians we are responsible for educating our patients, including proper informed consent, as well as for performing appropriate diagnostic testing. To tell a woman to get a screening mammogram, if she is not inclined to do so, does not benefit the patient. Infrared breast thermography may offer a viable breast cancer screening option for these women. It may also prove useful for those women who are not ideal screening mammography candidates, such as those under the age of 40, where the risk of mammography exceeds the benefit. Screening thermography can be safely performed on women of any age. For women at high-risk, thermal imaging at a young age (between 20 and 30) can provide a thermovascular baseline that may prove useful when applied in a serial fashion, thereby minimizing radiation exposure that is currently being cautioned. For women not at high-risk for breast cancer, it must also be noted that the combined use of thermography and mammography has been shown to improve survival rates by 61%--likely owing to earlier diagnosis than either screening tool individually.19
Future research should focus on clarifying these issues, including whether early thermographic screening in women with the BRCA mutation performed in a serial fashion can assist in earlier diagnosis. Additionally, the development of infrared assessment guidelines that take into account isolated serial changes, such as elucidated in this study, seem warranted.
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