Are cardiac patients at higher risk for cancer from their imaging?

[Hello_80]

A presentation was made at the 2010 AHA (American Hospital Association) meeting  that concluded: "For every 10-mSv increase in Low Dose Ionizing Radiation (LDIR), the risk for cancer increased by 4.4% in women and 2.1% in men."
This was a Canadian respective study* that did not consider cohort cancer risk vs control risk (i.e., patients referred for cardiac studies might also be at higher than average cancer risk).

Do you think this is true or have any comment?

Is it not time to properly do the extremely difficult task of long-term prospective studies and are you calling for studies to be done? You guys seems to be fair-minded.

(1) Do you agree with the conclusions of a reported study regarding the quantitative risk of LDIR at 10 mSv, (2) do you think it is time to launch on a long-term prospective human epidemiological study to look for risk from low dose ionizing radiation, and (3) are you calling for such studies?

v/r
Yonas

[CCFHeartMD10]

This issue has generated a lot of debate in the medical community. The study you quote had a number of important limitations, the chief one being that the patients they studied seemed to have a higher risk of cancer at baseline than the general population, thus the results may over-estimate the risk of these scans. In addition, the length of follow-up in that study was not sufficiently long to pick up a signal of increased risk of cancer from exposure to radiation - most estimates of the interval between radiation exposure and cancer development are longer than the 5 or so years of follow-up in that study. The patients studied were sick, and older, meaning they were at more risk for cancer regardless of radiation exposure.
Much of the study of cancer risk from radiation comes from data on survivors of the atomic bombs in 1945. While this area has been studied, it is extremely difficult to study due to 1) the long follow-up required; 2) the multiple sources of everyday radiation exposure, such as radon gas, and even flying; and 3) the competing risks such as dietary, genetic and other environmental factors (such as smoking).
Nevertheless, the medical community (for instance the AHA - Gerber et al, Circulation 2009; 119: 1056-1065) has called for such studies to help better understand these risks.

[curmudgen]

Without seeming to be argumentative what's the alternative for patients that need imaging studies for diagnosis of disease and treatment protocols?  With every pill and procedure we expose ourselves to the benefits as well as the risks.  Each of us, in consultation with physicians, have to decide where that line falls.  Putting this into perspective there are many life style choices being made that raises the cancer risk levels by 2-5%.  Certainly that's not a large number in the grand scheme of things, just to the person or persons affected.  ---commentary from an aging Biology Professor.....