Technologies for Detecting Breast Cancer

Originally published in Boomers & Beyond, Janary 1, 2014.

Do I Have Breast Cancer or Not?

Only a biopsy can prove the existence of breast cancer. A woman’s first question should be whether she has symptoms that suggest she needs a biopsy. The second question is which technology can best identify those symptoms.

The most common technology for detecting symptoms is mammograms, which take X-rays of breast tissue. The second most common technology is the MRI. A third technology, thermography, is showing a lot of promise for early detection of breast cancer.

Analysis of Mammograms

Many women owe their lives to mammograms. According to the American Cancer Society (ACS), mammograms are not very accurate, but they have found signs of cancer for many women. A mammogram detects regions of hardened or dense tissue, which may be caused by cancer but also by cysts, hormonal changes, and non-cancerous tumors.

mammogram.cancer

According to the ACS, “A mammogram will miss some cancers, and it sometimes leads to follow up of findings that are not cancer, including biopsies.” Most abnormal results are false positives.

A false positive occurs when the mammogram incorrectly suggests the presence of cancer. It may cause fear and lead to unnecessary and sometimes risky biopsies. A false negative is a worse problem. The mammogram doesn’t seem abnormal but the woman has cancer.

One report published by the National Cancer Institute notes the false negative rate is 40% among women aged 40–49, and a study published by the National Institute of Health claims that mammograms miss 10% of malignant tumors in woman over age 50. “Overall, screening mammograms miss about 1 in 5 breast cancers” (ACS).

Mammograms are particularly ineffective for younger women with dense breast tissue. The ACS explains that “[mammograms] do not work as well in women with dense breasts, since dense breasts can hide a tumor. Dense breasts are more common in younger women, pregnant women and women who are breastfeeding, but any woman can have dense breasts.”

Mammograms are also a challenge for women with smaller breasts and cannot produce images of tissue that does not fit in the mammogram machine.

Inflammatory breast cancer (IBC), a common breast cancer, is also difficult to find. As the ACS explains, “Because of the way inflammatory breast cancer (IBC) grows and spreads, a distinct lump may not be noticeable during a clinical breast exam, breast self-exam, or even on a mammogram…Unfortunately, because IBC grows and spreads so fast, screening is not generally helpful for finding this disease early.”

On the other hand, mammograms do what they are designed to do: provide an X-ray image of a portion of the breast. And, as I said before, they have saved many lives.

Analysis of MRIs

Magnetic resonance imaging (MRIs) uses magnetic and radio waves to take images of breast tissue. The ACS does not recommend them as the first form of screening, but does recommend them in conjunction with mammograms, either as a follow-up or in addition to mammograms for some high-risk women.

They are good. In fact, they are too good.

Although MRI is more sensitive in detecting cancers than mammograms, it is more likely to find something that turns out not to be cancer…False-positive findings have to be checked out to know that cancer isn’t present, which means coming back for further tests and/or biopsies. This is why MRI is not recommended as a screening test for women at average risk of breast cancer, as it would result in unneeded biopsies and other tests in a large portion of these women. (ACS)

On the other hand, the ACS recommends that certain high-risk women start getting both mammograms and MRIs at age 30.

Here is a typical scenario. A mammogram shows a suspicious region of the breast tissue. The false positive and false negative rates are high, so she goes for an MRI for follow-up. The MRI also shows a problem, but MRIs have an even higher false positive rate than mammograms. However, because both technologies suggest cancer signs, she next goes for a biopsy. Fortunately for her, the biopsy doesn’t indicate cancer. 

MRIs don’t find cancer. What they do is confirm cancer symptoms and suggest the need for a biopsy. If the biopsy confirms cancer, treatment can begin.

Analysis of Thermography

Unlike mammograms and MRIs, which create images of breast tissue, thermography creates images of how the body is responding to conditions. Infrared cameras create images of heat produced by the body in response to distress, including breast cancer.

Thermographic image of breast cancer (white area)

Thermographic image of breast cancer (white area)

Thermography, which is fairly new to American medicine, is more common in the Far East, where medicine often focuses on the body’s processes.

The premise behind using thermography is based on how cancer grows. From their onset, cancerous cells emit a protein that promotes the growth of new arteries. With additional blood flow, the temperature rises. Cancerous cells also have a higher than typical metabolic rate, meaning they naturally produce higher temperatures. In both cases, infrared cameras detect the increased heat.

This is a different way of looking for breast cancer, but early studies of thermography had unflattering conclusions. The field was fairly new without established protocols for taking images. Thermographic images were also often compared to mammograms. When thermal images suggesting a response to breast cancer were not confirmed by a mammogram, researchers assumed thermography was faulty.

The ACS does not recommend thermography as a replacement to mammograms. The ACS notes that “Although [thermography] has been promoted as helping detect breast cancer early, a 2012 research review found that thermography detected only a quarter of the breast cancers found by mammography.” (A research review is an examination of previously published studies, not a research study.)

Other researchers’ studies are more positive. For example, Gautherie and Gros (2006) found that “The more rapidly growing lesions with shorter doubling times usually show progressive thermographic abnormalities consistent with the increased metabolic heat production associated with such cancers. Thermography is useful not only as a predictor of risk factor for cancer but also to assess the more rapidly growing neoplasms.”

As breast cancer remains the most prevalent cancer in women and thermography exhibited superior sensitivity [compared to mammography], we believe that thermography should immediately find its place in the screening programs for early detection of breast carcinoma, in order to reduce the sufferings from this devastating disease. (Kolarić et al., 2013)

Schaefera, Závišekb, and Nakashimac (2006) concluded that

Medical thermography has proved to be useful in various medical applications including the detection of breast cancer where it is able to identify the local temperature increase caused by the high metabolic activity of cancer cells. It has been shown to be particularly well suited for picking up tumours in their early stages or tumours in dense tissue and outperforms other modalities, such as mammography, for these cases.

Is thermography perfect? No. Research studies suggest accuracy is as high as 92%: higher than mammograms but not perfect. Can thermography show that a woman has breast cancer? No. Only a biopsy can do that. Can thermography replace mammograms? No. The FDA does not allow thermography practitioners to make that claim, although the FDA approved thermography as an adjunctive to mammograms.

What’s a Woman to Do?

The best advice is this: For the best possible detection of breast cancer, use a variety of imaging techniques. And if your mammogram has questionable findings, don’t panic. As the ACS states, most abnormal mammograms and even “most biopsy results are not cancer.”

Citations and Resources

http://www.cancer.org/cancer/breastcancer/

http://onlinelibrary.wiley.com/doi/10.1002/cncr.2820450110/full

http://www.sciencedirect.com/science/article/pii/S0031320308003270

http://www.ncbi.nlm.nih.gov/pubmed/23941007 

Summary of Mammography vs. Thermography

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