Pregnancy Bliss | Reproductive Health Answers
In May 2010, the prestigious medical journal, the Lancet, published a report of the results of a German study comparing the efficacy of mammography and MRI scanning in detecting early breast cancer.
At a very basic level, the difference in the efficacy of the two methods looks stark. The University of Bonn researchers reported a detection rate of 56% for the mammogram and 92% for MRI.
A mammogram is the long-accepted screening tool for breast cancer. A mammogram is basically an x-ray of the breast.
In the UK, women aged 50 and above are given a free mammogram every three years. An invitation to have a mammogram is sent out once a woman reaches 50 and three yearly thereafter. This program is estimated to save over 1400 lives every year with an uptake of around 75% of those eligible.
In the US, things are rather different. Breast cancer screening is also offered to women of 50 and above. However, the mammography frequency is higher as it is recommended to be annual. There is no scientific evidence that the higher frequency is more effective
Recently, there was a media and political storm on the subject in America. An NIH Consensus Conference concluded that routine mammography was not indicated universally for women in their forties. The pressure was such that the advice was reversed. Now, the official line is that women in their 40s should have a mammogram every year or two.
It is the case that a quarter of all new breast cancer cases are diagnosed in women below the age of 50. In fact 1 in 20 will be under 40 years of age. It has been increasingly evident that breast cancer in these younger women is likely to be due to some form of genetic pre-disposition.
Many women would have heard of the genes called BRCA1 and 2. These are actually normal genes and are not a risk factor. Everybody has them. In some cases, however, these genes undergo mutation and it is that alteration that ratchet up the risk for breast cancer. The gene mutation can then be inherited through generations and this is where family history becomes important.
The lifetime risk of an average woman to get breast cancer is estimated to be 1 in 8. For a woman with BRCA1 or 2 gene mutations, the risk is increased dramatically to about 1 in 3, sometimes much higher. These are the individuals who need to be identified by the screening programs to enable them to get individualized surveillance.
Researchers have been busy trying to identify other rogue genes that might be responsible for individual women’s increased risk of breast cancer. In May 2007, the journals Nature and Nature Genetics published results of an international collaboration research which had identified 4 common genes which, when mutated, increased the risk of breast cancer to some degree (not as high as BRCA1 and BRCA2 mutations). It is believed there are many more yet to be discovered.
Techniques for identifying the gene mutations are getting increasingly refined and there is hope that in a decade or so, universal genetic screening might be possible. This will allow for targeted surveillance for those identified as being at increased risk of developing breast cancer. It will also allow a more accurate quantification of the degree of each individual’s risk
It is important for every woman to know that a mammogram will not detect every breast cancer lesion, particularly so for the very early ones. Other factors also come into play. Low Body Mass Index (BMI), previous breast surgery and use of HRT might reduce the sensitivity slightly.
The study quoted at the beginning of this article is not the first one to identify the potential superiority of MRI scanning in this area. It is, however, the first of its size and also showing such a dramatic difference. It is possible that as we go forward, MRI might be incorporated or even gradually replaces x-ray mammography as a standard tool for breast cancer screening. This might be particularly important for younger women who might be identified to be at moderate or high risk and who need surveillance.
Currently, experts are in agreement that young women below the age of 40 are not best served by routine mammography, partly because the sensitivity may not be as good, their overall risk is low and also because of the repeated exposure to radiation that this will entail. The risk-benefit sum just doesn’t add up. With MRI scanning (which does not involve radiation), all these obstacles are eliminated in one fell swoop. Of-course further studies will be required and in many countries, including the UK, logistical obstacles including easy accessibility to the service will need to be overcome.
Last update: May 31, 2012