Is There a Connection Between the Incidence of Brain Cancer Among Interventional Cardiologists and Their Radiation Exposure?

Researchers have reported cases of brain tumors among cardiologists and radiologists that work in cardiac catheterization laboratories. In addition to support from the literature, documenting 5 cases of brain tumors, a new study reports 4 new cases of brain malignancies, all in the left hemisphere of the brain.[1]

Of the previously reported cases, 2 cases are also left-sided malignancies and 3 cases are unconfirmed in terms of tumor location. All of the malignancies are reported in long-term interventional clinicians, from 14 to 32 years on the job-2 of the cases were in Toronto, Canada; 2 in Haifa, Israel; 2 in Paris, France; and 3 in Sweden.

MRI shows areas where brain cancer has metastasized in the occipital lobe (bright blue).

Interventional cardiologists work extensively in cardiac catheterization laboratories, or "cath labs," where they are exposed to low doses of ionizing radiation, a potential health risk. In their EuroIntervention report, Dr. Ariel Roguin and colleagues state that the left side of the head is known to be more exposed to radiation during procedures and that the "connection between occupational radiation exposure is biologically plausible." While chance occurrences cannot be ruled out, the authors believe that raising awareness about the potential risk and gathering more data points will help to elucidate the actual risk.

Chronic low-dose ionizing radiation can cause the accumulation of somatic DNA damage in cells, resulting in chromosomal aberrations or mutations that can contribute to cancer. This is the reasonable biological link between radiation exposure and cancer incidence.

Cardiologists who work in cath labs have the highest radiation exposure among health care professionals, according to the author. Therefore, increased awareness of radiation safety and training in self-protection is essential. While radiation shields are used, there are no general precautions for head protection. "Most cardiologists wear lead on many parts of the body-but the head is usually not covered," commented Manesh Patel, MD, an assistant professor at the Duke University School of Medicine.

Dr. Jeffrey Schwartz, a practicing cardiologist in Morristown, New Jersey, says it's not surprising. "The cardiologist stands right next to the patient and the x-ray tube for the entire procedure. It's a risk we take in order to take care of our patients, though few people appreciate the fact," said Dr. Schwartz. "I believe there is more leukemia among cardiologists as well, though that is anecdotal."

Lead author Ariel Roguin, MD, PhD, told CancerNetwork in an email correspondence that he started looking into this topic after a senior attending died of glioblastoma multiforme. "He performed thousand of procedures over the past years and was exposed to x-ray radiation, almost on a daily basis, for approximately 32 years," said Roguin. "He underwent radical surgery followed by radiotherapy and chemotherapy. He died several months after diagnosis, at the age of 63."

The next step, according to Roguin, is to get more accurate incidence numbers of brain cancer. "We have to understand the magnitude of this finding. The next step is trying to get an accurate measure of the risk by having the cardiology community report the actual incidence numbers!"

What is the average dose of radiation that cardiologists are exposed to regularly? According to Dr. Patel, this in not known and likely varies by center and the type of procedure.

"Cath and EP doctors do wear dosimeters and these are routinely checked by local radiation committees. Fifty mSieverts is the US maximum for radiation plant workers for one year and many institutions use this numbers," he added. Whether cardiologists consistently and properly wear dosimeters, whether readings analyses are enforced, and what the level of compliance is are all questionable and likely vary by institution and country.

Training, understanding the exposure risk, and implementing head protection are all precautions that should be better implemented and perhaps enforced. Hopefully, exposed clinicians will adhere to the maximal protection levels as long as the link of brain cancer and radiation exposure is uncertain.

Dr. Patel is concerned and surprised by the findings and noted that "many other vital tissues may be exposed." He believes that education and increased awareness are important and that national professional groups should harmonize data collection and standards.

"I think research in radiation exposure for the health care field is important and the case series highlights the need for continued precaution," added Dr. Patel.

Reference

1. Roguin A, Goldstein J, Bar O. Brain tumours among interventional cardiologists: a cause for alarm? Report of four new cases from two cities and a review of the literature. EuroIntervention. 2012;7:1081-1086.