MAMMOGRAPHY and BREAST THERMOGRAPHY*
Screening and Diagnosis of Breast Cancer
Screening and Diagnostic Mammograms
· A mammogram is a picture taken of the breast by radiation. It is an x-ray picture of the breast.
· Screening mammograms are used to check for breast cancer on women who have no signs or symptoms of the disease. This type of mammogram usually involves two x-ray pictures, or images, of each breast. The x-ray images are said to make it possible to detect tumours that cannot be felt, ie early diagnosis. They can also reveal micro-calcifications (tiny deposits of calcium) that sometimes indicate the presence of breast cancer.
· Diagnostic mammograms are used to check for breast cancer after a lump or other signs or symptoms of the disease have been found. Beside a lump, signs of breast cancer can include breast pain, thickening of the skin of the breast, nipple discharge, or a change in breast size and shape. These signs may also be signs of benign conditions such as fibrocystic disease, infection or a vascular disease.
Diagnostic mammography takes longer than screening mammography because more x-rays are needed to obtain views of the breast from several angles. The technician may magnify a suspicious area to produce a detailed picture that can help the doctor make an accurate diagnosis.
The Mammogram Procedure
The process requires the breasts, one at a time, to be compressed between the x-ray plates, and the appropriate x-rays taken. The radiographer will position and compress the breasts in turn between two flat plates for about 10 to 15 seconds while the x-ray in being taken. The x-ray is subsequently examined by a health professional. Compression of the breast is vital to give the best possible picture and to minimise the amount of radiation that is used. If not compressed adequately, the x-ray picture is likely to be blurred.
The procedure is said to be safe "as there is minimal exposure to radiation during a mammogram because modern mammography machines use the smallest amount of radiation possible while still achieving high quality x-rays". However it should be noted that the body is still being exposed to x-rays and that x-rays may cause cancer.
The purpose of breast screening is to reduce mortality from breast cancer by early detection. To reduce mortality, screening must detect life-threatening disease at an earlier, more curable stage. Effective cancer screening programs therefore both increase the incidence of cancer detected at an early stage and decrease the incidence of cancer presenting at a late stage.
Australian Recommendations for Breast Screening
The National Breast Screening Program is under the direction of BreastScreen Australia (www.cancerscreening.gov.au). The Federal Budget of the Australian Government, 2013-2014, planned to finance BreastScreen Australia, to enable them to finance an increase in the target age-range for breast screening by five years, from the present age-range for women of 50-69 years, to the age-range for women of 50-74 years.
Thus the recommendation is: mammography every two years for women 50 years of age and over until the age of 74 years.
"Participants in the BreastScreen Australia Program would result in around 8 deaths prevented for every 1,000 women screened every 2 years from age 50 to age 74".
"Over-diagnosis" for breast screening does not refer to error or misdiagnosis, but rather to breast cancer diagnosed by screening that would not otherwise have been diagnosed during a woman's lifetime. "Over-diagnosis" includes all instances where cancer detected through screening (ductal carcinoma in situ or invasive breast cancer) might never have progressed to become symptomatic during a woman's life, ie carcinoma that would not have been detected in the absence of screening.
Estimates of over-diagnosis vary widely. Based on UK and European reviews, it is estimated that for every 1,000 women in Australia who are screened every two years from the age of 50 to age 74, around 8 (between 2 and 21) breast cancers may be found and treated that would not have been found in a woman's lifetime.
What are the Benefits of Screening Mammograms?
Early detection of breast cancer with screening mammography means that treatment can be started earlier in the course of the disease, possibly before it has spread. Women over 50 years are routinely advised to have second yearly mammograms, and it is widely believed that doing this is beneficial to women's health. Some suggest that mammography should be commenced at age 40 and carried out yearly.
Although experts agree that diagnostic mammograms are beneficial (cases where there is a breast lump or other symptoms), there is much controversy about screening mammograms, which are performed in apparently healthy women who have no signs of breast cancer. Mammograms may detect breast cancer, although many people believe mistakenly that they prevent breast cancer.
What is relevant, and the real purpose of screening mammography, is to reduce mortality from breast cancer by early detection.
What are some of the Potential Drawbacks of Screening Mammograms?
· Finding cancer early does not always reduce a woman's chance of dying from breast cancer.
Even though mammograms can detect malignant tumours that cannot be felt, treating a small tumour does not always mean that the woman will not die from cancer. A fast-growing or aggressive cancer may have already spread to other parts of the body before it is detected. Women with such tumours live a longer period of time knowing that they are likely to have a fatal disease.
· Other life-threatening health conditions
Screening mammograms may not help prolong the life of a woman who is suffering from other more life-threatening conditions.
· False-negative results
False-negative results occur when mammograms appear normal, or are reported as normal, even though breast cancer is present. It is estimated that, overall, screening mammograms miss about 20% of breast cancers that are present at the time of screening.
The main cause of this is breast density. Breast consists of both dense tissue (glandular tissue and connective tissue, known as fibroglandular tissue) and fatty tissue. On a mammogram, fatty tissue appears dark, whereas fibroglandular tissue appears as white areas. Tumours have a similar density to fibroglandular tissue and are thus harder to detect in women with denser breasts.
False-negative results lead to a delay in treatment and a false sense of security for affected women.
· False-positive results
False-positive results occur when radiologists decide mammograms are abnormal but no cancer is actually present. It is recommended that all abnormal mammograms should be followed up by additional testing such as diagnostic mammograms, ultrasound and/or biopsy.
False-positive mammogram results can lead to anxiety and other forms of psychological distress in affected women. The additional testing required to rule out cancer can also be costly and time consuming and can cause physical discomfort.
· Over-diagnosis and Over-treatment
Over-diagnosis is discussed above. With over-diagnosis, the treatment of these cancers, that will never cause symptoms or threaten a woman's life, is not needed and leads to "over-treatment". Over-treatment exposes women unnecessarily to the adverse effects associated with cancer therapy.
· Radiation exposure
Modern mammogram equipment designed for breast x-ray use are said to use very low levels of radiation. The risk of harm from this radiation is said to be extremely low.
Repeated x-rays have the potential to cause cancer.
The benefits of mammography are said to nearly always outweigh the potential harm from radiation exposure.
We are exposed to approximately 3mSv (millisievert) of radiation from natural sources (mainly from Radom gas) in one year. One 10-hour flight exposes us to 0.030 mSV.
Using plain x-ray film the following are some comparative, average measures:
|Chest x-ray, 2 views||0.100mSv|
|Dental, 4 bite wings||0.005mSv|
|CT scan, abdomen||8,000mSv|
|CT scan, brain||2,000mSv|
Old terminology: RAD is Radiation Absorbed Dose. REM is Roentgen Equivalent (in) Man. Essentially, 1 RAD = 1 REM = 10mSv.
Treatment for breast cancer by radiation is in the order of 5,000 RADS or 50,000mSv or 50Sv. It can be as high as 80Sv. This is also referred to as 80Gy (Gray unit, used for high levels of radiation).
The sievert is the standard unit in the International system of Units:
1Sv (Sievert unit) = 1 joule/kilogram - a biological effect. This is equivalent to 1 Gray.
1Gy (Gray unit) = 1 joule/kilogram - a physical quantity.
How Effective is Screening Mammography?
To try to answer this all important question, the following summarises two recent studies published in respected peer-review journals.
Study 1 - Effect of Three Decades of Screening Mammography on Beast-Cancer Incidence.
This study was published in the New England journal of Medicine in November, 2012 (N Eng J Med 2012; 367: 1998-2005). The authors were Drs Archie Bleyer and H. Gilbert Welsh.
The background to the study: To reduce mortality, screening must detect life-threatening disease at an earlier, more curable stage. Effective cancer-screening programs therefore both increase the incidence of cancer detected at an early stage and decrease the incidence of cancer presenting at a late stage.
The authors used Surveillance, Epidemiology and End Results data to examine trends from 1976 through 2008 in incidence of early-stage breast cancer (ductal carcinoma in situ and localised disease) and late stage breast cancer (regional and distant disease) among women 40 years of age or older.
To quote Dr Gilbert Welsh, writing about the results:
"The study looks at the big picture, the effect of three decades of mammography screening in the United States. After correcting for underlying trends and the use of hormone replacement therapy, we found that the introduction of screening has been associated with about 1.5 million additional women receiving a diagnosis of early stage breast cancer.
"That would be a good thing if it meant that 1.5 million fewer women had gotten a diagnosis of late-stage breast cancer. Then we could say that screening had advanced the time of diagnosis and provided the opportunity of reduced mortality for 1.5 million women.
"But instead, we found that there were only around 0.1 million fewer women with a late-stage breast cancer. This discrepancy means that there was a lot of over-diagnosis: more than a million women who were told they had early stage cancer - most of whom underwent surgery, chemotherapy or radiation - for a "cancer" that was never going to make them sick. Although it's impossible to know which women there are, that's pretty serious harm.
"We found no change in the number of women with life-threatening metastatic breast cancer.
"Beast cancer is arguably the most important cancer for non-smoking women to care about. Diagnostic mammography - when a woman with a breast lump gets a mammogram to learn if its something to worry about - is an important tool. No one argues about this. Pre-emptive mammography screening, on the other hand, is, at best, a very mixed bag - it most likely causes more health problems than it solves."
The authors of the study conclude:
"Despite substantial increases in the number of cases of early-stage breast cancer detected, screening mammography has only marginally reduced the rate at which women present with advanced disease. Although it is not certain which women have been affected, the imbalance suggests that there is a substantial over-diagnosis, accounting for nearly a third * of all newly diagnosed breast cancers, and that screening is having, at best, only a small effect on the rate of death from beast cancer."
*The authors "estimated that in 2008, breast cancer was over-diagnosed in more than 70,000 women; this accounted for 31% of all breast cancers diagnoses."
The following comments were made in the National Cancer Institute's Cancer Bulletin for November 27, 2012:
"Women need to understand that screening has positive and negative consequences. This is one of many studies that is expanding the discussion about screening. It demonstrates that women need to make decisions based on their circumstances, not just on recommendations." (Dr Stephen Taplin)
Study 2 - Twenty five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomised screening trial.
This study was published in the British Medical Journal, February 2014 (BMJ 2014; 348:g366). The authors were Prof. Anthony B Miller and associates.
The objective of this prolonged study was to compare breast cancer incidence and mortality up to 25 years in women aged 40-59 who did or did not undergo mammography screening. It involved 15 screening centres in 6 Canadian provinces.
89,835 women, aged 40-59, were randomly assigned to 5 annual mammography screenings (44,925) or to control, no mammography (44,910).
Women aged 40-49 in the mammography group and all women aged 50-59 in both groups received annual physical breast examinations. Women aged 40-49 in the control group received a single examination followed by the normal care in the community.
The main outcome measure was: death from breast cancer.
During the 5 year screening period, 666 invasive breast cancers were diagnosed in the mammography group and 524 in the control group, and, of these, 180 women in the mammography group and 171 women in the control group died from breast cancer during the 25 year follow-up period. The findings for women aged 40-49 and 50-59 were almost identical.
During the entire study period, 3,250 women in the mammography group and 3,133 women in the control group had a diagnosis of breast cancer and 500 and 505 respectively died of breast cancer.
Thus the cumulative mortality from breast cancer was similar between women in the mammography group and in the control group.
After 15 years of follow-up, a residual excess of 106 cancers was observed in the mammography group, attributable to over-diagnosis.
"Annual mammography in women aged 40-59 years does not reduce mortality from breast cancer beyond that of physical examination or usual care when adjuvant therapy for breast cancer is freely available. Over all, 22% (106/484) of screen detected invasive breast cancers were over-diagnosed, representing one over-diagnosed breast cancer for every 424 women who received mammography screening in the trial."
In summary, this study, involving almost 90,000 women over a quarter of a century, showed that death rates from breast cancer were essentially the same in women who had mammograms and those who did not. And the screening had negative effects: one in five cancers found with mammography and treated was not a threat to woman's health and did not need treatment such as surgery, chemotherapy or radiation.
This study has reignited the debate about whether or not an annual or second-yearly screening mammogram is a wise choice for most women.
Mammography, like other detection/diagnostic tools, is imperfect. It misses about 20% of lumps due, for example, to dense breast and other factors and results in overdiagnosis in some 22% of cases, with unnecessary surgery, chemotherapy or radiation.
Women need to carefully consider these factors, and make informed decisions for themselves, as to what is best for them. It is likely that friends, caregivers and even commercial interests may tell them that having routine mammograms is the only rational choice. BreastScreen Australia is at the forefront in recommending screening mammography.
What really helps is knowledge and supportive counselling.
Is there an Alternative to Mammography?
Thermography, or thermal imaging, uses a thermal sensitive camera to take an image of the infrared radiation (heat) being emitted from the skin. It is thus based on infrared heat emissions by the body's tissues. As the body cells go about their usual metabolic processes, they give out heat. Cancerous tumours tend to give out or emit more infrared heat than their healthy counterparts, i.e. they are hotter. This is because they have an increased blood supply and cell growth. The image provided is made up of a range of colours with hotter areas appearing red and cooler areas appearing blue. Thus it is possible to produce images that provide insight into the functional status of the breast.
As compared to normal tissue, cancer growths are regulated to a much lesser extent by the autonomic nervous system. For example, when cool air is blown over the breast, the autonomic nervous system lowers the amount of blood flow to normal breast tissue as a means of temperature control or regulation. The blood and blood vessels in the tumour site, however, are not under autonomic control and do not become cooler - thermography would thus show the abnormal tissues up as 'hot spots'.
Breast Thermography Procedure
The woman to be screened stands bare-chested about 3 meters from the machine, and imaging lasts for a few minutes. The results are available instantaneously on the monitor, and the information can usually be interpreted quickly with the relevant software. There is no pain, there is no physical compression of the breasts and no radiation enters the body. It is a non-invasive procedure.
Thermography as a physiologic test demonstrates heat patterns that are strongly indicative of breast abnormality. The test can detect subtle changes in breast temperature that indicate a variety of breast diseases and abnormalities. Once abnormal heat patterns are detected in the breast, follow-up procedures, including mammography, are necessary to rule out or properly diagnose cancer and other beast diseases such as fibrocystic disease etc.
Thermography, being non-radiation, non-contact and low-cost, has been demonstrated to be a valuable and safe early risk marker of breast pathology, and an excellent case management tool for ongoing monitoring and treatment of breast disease when used under carefully controlled clinical protocols. There are Thermography Clinical locations throughout Australia.
It should be noted:
Cancer Australia does not recommend thermography for the early detection of breast cancer. It is claimed that there is no scientific evidence to support the use of thermography in the early detection of cancer and in the reduction of mortality. BreastScreen Australia is in agreement, as is the National Health and Medical Research Council.
Prevention of cancer, including breast cancer, is the ideal.
Many of my newsletters are devoted to this all important topic of Cancer Prevention. The most recent is my March 2014 newsletter Defence Against Cancer. This article also lists previous newsletters addressing this topic, and they are recommended reading in conjunction with this newsletter.
*Copyright 2014: The Huntly Centre.
Disclaimer: All material in the huntlycentre.com.au website is provided for informational or educational purposes only. Consult a health professional regarding the applicability of any opinions or recommendations expressed herein, with respect to your symptoms or medical condition.
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