I've written before about how bad human beings are at assessing risk (see http://www.novamedgroup.com/measles-outbreak) and lately several conversations with patients have highlighted for me just how important it is for family physicians to engage their patients in a dialogue about risk.
I keep hearing from my patients who refuse mammograms that the reason they are not getting routine  breast cancer screening is that they are concerned about the effects of radiation. They are especially worried about the cumulative effects of the radiation on their overall cancer risk.
Radiation is certainly something we should all be thinking about and aware of when we order imaging tests but I would like to put the concern over mammograms into perspective.
A single mammogram gives about a 0.8 mSv dose of radiation which raises cancer risk by 0.004%.
If a 50 year old woman follows the USPSTF guidelines and gets a mammogram every other year until she is 75, her additional overall cancer risk will be 0.05%. The average woman has a 12% chance of getting breast cancer.
On the other hand, I get asked all the time if I can order whole body CT scans to screen for disease in healthy patients. The dose of radiation you get from a whole body CT scan? 12 mSv! If you got this yearly as a sort of "virtual checkup" like some centers are advertising, there is a 1 in 50 chance you will die of a radiation related cancer. (Not to mention all of the things that would be found that I would have to chase up and in the end would likely not be anything dangerous. In my opinion, a whole body CT scan in an asymptomatic patient is like opening up Pandora's box).
To sum up, there is definitely a time and place to worry about how much radiation you are getting, but routine mammography is not it and no one should avoid a potentially life saving test over a fear of radiation.
For CT scans and other high dose imaging tests it is a good idea to keep track of your own radiation risk.
http://www.xrayrisk.com is a fantastic site that lets you put in all your tests and it will calculate your cumulative risk.

Breast Cancer Awareness Month and BRCA mutations

In honor of breast cancer awareness month, I thought I'd write about 2 highly pertinent topics: BRCA testing and automated whole breast ultrasound.
You may be familiar with BRCA gene mutations. Angelina Jolie famously had a preventive double mastectomy in 2013 after she was found to be a carrier for one of these mutations. There are 2 known genes, BRCA-1 and BRCA-2. Mutations in these genes significantly increase a woman's risk of both breast and ovarian cancer.
BRCA has been back in the news lately thanks to a study from Mary-Claire King, the researcher who first identified BRCA-1.
The study found that even women who have no family history of breast cancer can carry a BRCA gene mutation and that it increases their risk by the same amount as women who do have a family history.
Here's the problem: the study was done in a particular ethnic group known as Ashkenazi Jews who have a much higher rate of BRCA gene mutations than the general population.
Dr. King has called for universal screening for ALL women regardless of ethnicity  based on these findings even though the prevalence in the general population is much lower. Most non-Ashkenazi Jewish women with breast cancer do not have a BRCA mutation. Screening everyone may lead to an increased number of false positives as well as increased false sense of security. I worry that women will get tested, get a negative result and then neglect routine breast cancer screening as a result. After all, 1 in 8 women will get breast cancer in their lifetime and most of these do not carry a BRCA mutation. Screening may also lead to women having unnecessary radical surgeries like mastectomies and oophorectomies. On the plus side, some women may be more proactive about their screening and may get additional tests like breast MRI or may take a medication to reduce their risk, however we already have a well established risk predictor model called the Gail Breast Cancer Risk Model as well as criteria for who should get BRCA testing. Instead of universally testing all women for a mutation that they are unlikely to have, I would like to see primary care doctors using these risk models and talking to women about their personal risk and what the screening options are.
Which leads me to a new screening tool for breast cancer. Some of you may have noticed that you now get a notification from you breast radiologist that you have "dense breasts". Your breasts are considered dense if you have a lot of fibrous or glandular tissue but not much fat.Dense tissue appears white on a mammogram. Lumps, both benign and cancerous also appear white so dense breasts make it more difficult for doctors to spot cancer on mammograms.
A JAMA study published in 2008 shows that when adding ultrasound to mammographic screening, researchers found an additional 1.1 to 7.2 cancers per 1,000 in women with dense breasts.
So if you have a history of dense breasts, ask your doctor if additional breast ultrasound would be right for you.