What does the test involve?
Having a breast thermogram involves sitting topless in front of an infrared camera (operated by a female technician) and changing position every so often so that different areas of the breasts can be imaged. The technician does not touch the woman’s breast (or any other body parts.) Some thermography providers ask their clients to place their hands in a bowl of icy cold water for a one minute so that differences in blood flow within breast tissue can be observed before and after this “cold challenge” test. The cold water can be uncomfortable.
Since thermography measures heat being emitted from breast tissue, it is important to avoid activities that may influence the heat of the breasts prior to the thermogram. Such activities include vigorous exercise within four hours of the thermogram, and no hot drinks within an hour of the thermogram. Women are also advised not to shave their armpits on the day of the thermogram, nor wear tight fitting clothing such as a bra on the day of their appointment.
(Thermography providers give their clients a list of written instructions of activities to avoid prior to the thermogram.)
Younger women are advised to schedule their appointment for the first half of their menstrual cycle. For post menopausal women, thermography can be performed at any time.
What does the test cost?
In NZ, thermography does not receive any sort of government funding, so clients pay the entire cost of the test. The cost of the test varies between providers but is generally around $200.
What are the potential benefits of the test?
Thermography is a test that measures heat emitted from the breasts. In healthy breasts the pattern of infrared radiation emitted from each breast will be very similar.
Variations in breast temperature detected by thermography can indicate potential problems with breast health. Significantly elevated temperature readings may indicate the likely presence of a cancerous breast tumour. Most breast cancers develop a dense network of blood vessels around them as they grow. It is the heat signature created by the additional blood vessels surrounding most breast cancers that can be detected by thermography.
Women who have a significantly abnormal thermogram are advised to consult their doctor about appropriate follow up testing so that the possibility of breast cancer can be confirmed or excluded.
Thermography potentially offers the chance to detect breast cancers while they at a very early stage of development as cancerous breast tumours begin to develop an enhanced network of blood vessels while they are still so small that they cannot be detected by mammography.
Thermograms that are mildly abnormal may indicate a need to take steps to improve breast health. Persistently abnormal thermograms are associated with an increased risk of breast cancer.
What are the risks associated with thermography?
1) The risks that apply to breast screening in general also apply to thermography [link to this page here]
2) Thermography does not involve exposure to radiation so is risk-free in this respect.
(See: NZBTA Thermogaphy Synopsis 2010.pdf, which can be downloaded from http://nzbta.org.nz/index.php?page=research)
3) There have not yet been large scale studies that prove that modern thermography screening does actually reduce mortality from breast cancer and the studies that have shown benefits from thermography have been relatively small compared to the studies of mammography. To the best of my knowledge there have not been any large scale studies to assess the benefits of making lifestyle changes after a thermogram has detected an abnormality. (There are case histories that show improvement in serial thermograms after lifestyle interventions have been instituted but no organised research in this area.)
How accurate is the test?
When breast thermography is conducted by a trained operator in an appropriate setting (i.e. a room that is at a constant temperature and free from drafts etc) and the results are analysed by computer and reviewed by a doctor with appropriate training, it offers a high degree of accuracy in detecting the variations in breast temperature associated with most breast cancers.
The American Journal of Surgery (Vol 196, No. 4, October 2008) discusses a study in 1980 in which the researchers found that patients with a thermogram rate stage Th IV or V “had a 90% chance of having cancer at the time of the study and more interestingly 38% of the patients of the 1,245 patients with Thermogram Th III (suspicious but not conclusive) developed cancer within 1-4 years of follow up.” The conclusion to their own study stated that “a modernized DITI system can be a useful adjunct test in detecting breast cancer with 97% sensitivity in this prospective trial of 92 patients.” (Sensitivity refers to the ability of a test to correctly identify that a patient is suffering from a certain condition.)
According to the International Journal of Thermal Sciences 48 (2009) 849-859:
“International research about thermography shows that the new thermography cameras, combined with analytical software and personnel can offer useful information about breast health.”… “For the last 1.5 decades of complying with the strict standardized thermogram interpretation protocols by proper infrared trained personnel as documented in the literature, breast thermography has achieved an average sensitivity and specificity of 90%. An abnormal thermogram is reported as the significant biological risk marker for the existence of or continued development of breast tumor.” (Specificity refers to the ability of a test to correctly identify that healthy people do not have the condition for which they are being tested.)
This means that the false positive rate and false negative rates for modern thermography are similar to that of mammography. In fact, for younger women thermography may be more accurate since breast tissue density does not affect the accuracy of thermography.
Thermography does have limitations as a test. It is less accurate for women who have very large breasts since the thermal signature of a tumour that is located deep in breast tissue may not be detected. Diffuse cancers that cause oedema or skin thickening may not be detected by thermography. Some breast cancers do not produce an abnormal heat signature and can also be missed by thermography. For this reason, thermography providers generally recommend that thermography is used in addition to mammography, rather than as a sole breast screening option.
Sources of additional information on thermography
This medical journal article discusses both mammography and thermography.
This is the website of the NZ Breast Thermography Association, an industry association established in 2010 to regulate the breast thermography in NZ. A summary of the findings of recent medical literature pertaining to breast thermography may be downloaded from the site and a copy of the full research review is available on request.
This is the website of Clinical Thermography Ltd, a company that offers breast thermography at various locations around NZ. The site includes a considerable amount of information about thermography.
This is the website of Safe2Scan Diagnostic Thermography which offers breast thermography in Nelson.