We Are Giving Ourselves Cancer

In yesterday’s New York Times, there was an editorial with the title above. The subject was the extensive use of CT scans and how we are “silently irradiating ourselves to death”.  The Op-Ed was written by two doctors at San Francisco Medical Center.  It generated a lot of comments, most of which were directed at the lack of clinical evidence regarding their theory. Nonetheless, this subject is near and dear to my heart as a cancer patient who undergoes a CT scan at least every 6 months.  Since my diagnosis in August 2010, I have had 8 CT scans!  My concern is that the radiation from CT scans can cause cancer.  My question is: What if you already have cancer?  I’m trying to understand the risk of missing something by not doing regular CT scans versus the risk of getting another type of cancer from all the radiation.  I’ve spoken with my oncologist about the frequency of my CT scans since I have been concerned about this for a while.  She said that if there were no cancer, we would not be doing CT scans but since I do have cancer, the CT scans are appropriate to monitor for changes.  I really do not know how to evaluate my risks; i.e., is the risk of radiation from the CT scan higher or lower than the risk of not catching cancer progression in time if we spaced the CTs farther apart?  Would an ultrasound or MRI be a better way to measure progression?  My doctor says an MRI would be better for liver tumors but not for other abdominal lesions.  Perhaps less frequent CT scans would be an appropriate approach?

The link to the NYT editorial is below:
http://www.nytimes.com/2014/01/31/opinion/we-are-giving-ourselves-cancer.html?_r=0

One of the ACOR list members posted an X-ray risk calculator that can give one an idea of their exposure to radiation and their additional cancer risk.  You can access the calculator at http://www.xrayrisk.com/.  I have no idea how credible this source is in evaluating radiation risk but it at least gives me a “radiology risk budget” and helps me to quantify the risk.   I put in my CT scans, 68-GA PET, mammograms and other radiological tests but not my dental x-rays and the small bowel x-ray series and came up with the results below.  My additional cancer risk from the tests I’ve already had is 1 in 84 or a 98.8% chance of having no effect from this exposure.  Again, I have no idea how accurate this calculator is but given this information, and my current stage 4 cancer diagnosis, I’d say it’s ok to keep doing CT’s. Perhaps the NYT editorial was overly alarmist?  Am I overthinking this whole subject?  I’d be interested in what others think about these risks.

Beth's Current X-Ray Risk Report

Study	Gender	Age	# of Exams	Dose (mSv)	Additional Cancer Risk
DEXA Scan (Bone Density)	Female	45	1	0.001	0.000000%
Chest, Abdomen and Pelvis CT	Female	51	2	42	0.274400%
Chest, Abdomen and Pelvis CT	Female	52	2	42	0.265227%
Whole Body PET	Female	53	1	14.1	0.086000%
Neck CT	Female	53	1	6	0.037000%
Chest, Abdomen and Pelvis CT	Female	53	2	42	0.256361%
Chest, Abdomen and Pelvis CT	Female	54	2	42	0.247791%
Mammogram (unilateral)(every other year)	Female	40-52	7	2.8	0.022000%
		Totals	18	190.901	1.188779%

An Additional Cancer Risk of 1.188779% is equal to 1 in 84 chances.

Or said another way, a 98.811221% chance of having no effect of the above studies.