From thermography to ultrasounds and mammography, many women are clueless as to which option is best, or if all three are required for optimal results
What’s the difference between a mammogram and a thermal scan?” Frequently asked this question by women, many who wrongly believe one method can replace another. Nothing could be further from the truth. Whereas mammograms and ultrasounds are structural imaging methods, with the ability to locate the exact area of suspicious tissue, thermography is a functional test which detects physiological changes within the breast. All of these tests can indicate that a problem exists or is developing and they all have their pros and cons, but none of them can diagnose cancer. These tools can alert the doctor that further screening or a biopsy may be necessary. The only test that can determine of the tissue is cancerous is a biopsy, which entails removal of a sample of suspicious tissue for examination under a microscope.
During a mammogram, the breast is firmly compressed between a plastic plate and an X-ray cassette that contains special X-ray film. An image of the breast tissue is obtained using ionising radiation, where the area of concern must have greater density to stand out against regular tissue to be detected.
Since the 1960s, mammograms have been considered the gold standard for early detect of breast cancer. They remain the preferred method to detect potentially invasive breast tumours as they can identify both breast cancers too small to feel during physical examination as well as non-invasive tumours which generally don’t spread outside of the breast tissue. However, researchers have recently been questioning the value of mammograms, maintaining that regular mammographic screening causes more harm than good, leading to a 30% overdiagnosis and overtreatment rate. This means that for every 2,000 women undergoing screening over a 10 year period, one will have her life prolonged and 10 healthy women, who would not have been diagnosed if there had not been screening, will be treated unnecessarily with no ultimate benefit. Furthermore, 200 women will suffer significant psychological distress for many months as a result of false positive findings.
Factors such as younger age, dense breasts, breast implants and hormone replacement therapy significantly reduce the ability of a mammogram to detect suspicious lesions. Since younger women tend to have more dense breasts (though this can occur in women of any age, and tends to increase in women on hormone replacement therapy), the younger the patient, the less effective mammography is likely to be. Mammography also increases the risk of rupture of breast implants.
The overall sensitivity of mammograms is approximately 80% (20% of cancers are missed) in women over 50. Sensitivity drops by between 10% and 30% (between 30% and 50% of cancers of missed) in younger women and in women with denser breasts, regardless of age.
Incidentally, mammography also increase the risk of radiation-induced breast cancer, particularly in younger women, as their breast tissue is more susceptible to the effects of radiation compared to older women. Research shows that a decade of annual screening may cause more deaths than it prevents if started at the age of 20 or 30. As a result, researchers have suggested starting mammographic screening at 50 as it is most effective at older ages and the associated radiation risks are lower.
Like mammography, ultrasound is a structural imaging technique, but it is safe and painless, and produces images of the inside of the body using high-frequency sound waves.
The primary use of breast ultrasound today is adjunctive; either as a follow-up assessment to help evaluate masses detected by a doctor during a physical examination, to detect abnormalities that may have been missed by mammography, or to evaluate abnormalities seen on a mammogram. Ultrasounds are beneficial at distinguishing solid masses form fluid filled cysts. As ultrasound don’t use ionising radiation, it’s the method of choice to evaluate breast abnormalities in women under 30 and pregnant women. In women between the ages of 30 and 39, ultrasound more effective at detecting palpable tumours (those that can be touched) compared to mammograms, but since ultrasounds are unable to see fine detail, they’re not sensitive enough to detect non-palpable tumours such as microcalcifications (calcium deposits in the breast cancer that sometimes point to cancer), whereas mammograms are.
A review of the literature and expert opinion by the European Group for Breast cancer screening concluded that there’s little evidence to support the use of ultrasound in mass screening of women with no symptoms at any age as it is associated with unacceptably high rates of both false positive and false negative outcomes.
Breast thermography is a non-invasive procedure that doesn’t involve compression of the breast tissue or exposure to radiation. Unlike mammograms and ultrasounds, which are structural imaging tests, thermography assesses physiological function through high-resolution temperature measurements. This involves an infrared camera picking up areas of high heat in the breast tissue, which potentially indicate a problem. The technology can detect focal areas of physiologic change caused by increased blood circulation and metabolic activity, but, because it can’t locate the exact area of suspicion inside the breast or features such as microcalcifications, it doesn’t compete with mammography, but rather than complements it.
One of the first studies to document the value of infrared thermography in the identification of breast cancer was by Gautherie and Gros in 1980. They reviewed thermograms performed on thousands of patients and found that patients with an obviously suspicious thermogram had a 90% chance of having cancer at time of the study. More interestingly, 30% of 1,245 patients who had been diagnosed with normal or benign breast conditions by conventional means (using methods including physical examination, ultrasounds, mammography, biopsy and fine needle aspiration) but with suspicious, inconclusive thermograms, develop cancer within one to four years. More rapidly growing tumours showed preogressive thermal changes consistent with increased metabolic heat generated by such tumours. This early research highlighted thermography’s value not only in predicting a woman’s risk for developing cancer in years to come, but also in differentiating more aggressive tumours.
By tracking areas of high heat over time, proponents of thermography assert that it can detect precancerous inflammatory changes and cancerous tumours up to 10 years earlier than mammography. Annual screening is recommended, starting at age 25. More frequent follow-ups may be recommended depending on the thermal findings detected. Modern research has confirmed thermography’s sensitivity as being high (97%) with an ability to reliably differentiate benign from malignant lesions. In another recent trial, modern digital thermography was also able to detect 97% of biopsy-confirmed breast malignancies. The same trial highlighted the benefit of thermography in people whose diagnosis of breast cancer can be difficult due to limitations in mammography, including younger women, men, women with dense breasts, or women with surgically altered breasts (implants, breast reduction).
Thermography is limited by the fact that thermal recordings are only a physiologic measure and therefore must be used as an adjunct to another structural test such as mammography or ultrasound. Infection or inflammation of breast tissue can also alter temperature recordings and lead to false positive findings. In addition, morbidly obese women and those with a breast size greater than DD prevent accurate recording of temperature from the undersurface of the breasts, so they may not be ideal candidates for thermography. Thermography is not currently recommended or approved as a substitute for screening mammography, and further investigation of findings should be made with alternative imaging techniques.
Early detection of invasive breast cancer is important, as patient survival is high when cancer is 2cm or smaller. If treated in the earliest stages, breast cancer survival rates of 95% are possible. Proper use of a combination of breast self-exams, physician exams, thermography (starting from the age of 25), ultrasound and mammography provide the earliest detection system available to date. The early alarm offered by thermograph allows you to implement lifestyle changes that can improve the health of your breasts proactively instead of waiting for a cancer diagnosis later.