Seeing Through the Medical Radiation Risk Story

Testicular cancer recurrence risk higher than later radiation induced cancer risks

December 21, 2012 / Author:  / Reviewed by: Joseph V. Madia, MD

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(dailyRx News) Imagine if you had a cancer that needed to be treated right away. The doctor orders CT scans. Would the fact that radiation exposure from the tests increases your lifetime cancer risks keep you from having the scans?

A new study found cancer risks caused by medical radiation exposure were many times lower than the risks of dying from untreated testicular cancer.

The study suggests both doctors and patients need to weigh the risks and benefits of imaging tests in making treatment decisions.

"Talk with your doctor about your medical tests."

Pari V. Pandharipande, MD, MPH, is an abdominal and genitourinary imaging specialist at Massachusetts General Hospital and Harvard Medical School in Boston. He is concerned that there has been a great deal of attention about the dangers of medical radiation – to the point that it can interfere with clinical decision making.

So he led a study to examine the benefit equation of medical radiation. Dr. Pandharipande and colleagues used computer models to project the outcomes of men with testicular cancer who were monitored with CT scans for 10 years following surgery to remove a diseased testicle. This procedure is known as an orchiectomy.

Surgery is the most common treatment for testicular cancer, which is followed by years of surveillance with CT scans.

Testicular cancer is the most common malignancy that develops in young men between the ages of 15-35. This year, about 8,600 men in the US learned that they had this cancer that can be cured if treated properly. Five years after diagnosis, 95 percent of patients are still alive.

The authors explained in the first years following treatment, a man’s risk of the disease remains somewhat elevated. As risk of return fades over time, the risk of latter cancers caused by radiation – what they call “radiation-induced cancers – starts to emerge.

The researchers contend that the way lifetime radiation exposure has been measured in the past – using what’s known as “lifetime risk metrics” – doesn’t take into account timing and the risks posed by an immediate health challenge.

Therefore, they used what they called “projections of life expectancy” that looked at the likelihood of dying from a current and pressing health concern – in this case, testicular cancer – compared to dying later from radiation exposure.

Dr. Pandharipande told dailyRx News, “Our study methods are based on a mathematical (Markov) modeling approach, and utilized hypothetical patient cohorts - as such, there are no study group numbers to report.” 

The researchers worked with three cohorts of men – aged 23, 33, and 43. Depending on the type of testicular cancer they had, the gentlemen were monitored with CT scans – several times a year in the beginning, which then dwindled to one a year or every two years.

They found that for the 33-year-old men, the risk of dying from testicular cancer was three times greater than dying from radiation-induced cancers.

dailyRx Contributing Expert and radiation oncologist, Benjamin Smith, MD, told dailyRx News, “This groundbreaking concept is imminently applicable and relevant to everyday medical decision making. For example, my son, at the age of 1, developed a urinary tract infection and required a medical imaging study called a voiding cystourethrogram to evaluate his genitourinary tract.

"I hated the idea of exposing my 1-year-old to ionizing radiation. But, on the flip side, he potentially had a life-threatening condition that required prompt evaluation to guide therapy. So, as much as I didn't want to expose him to radiation, I knew that the information gained from this test would be vitally important to his overall health, and we proceeded along with the test. The test results did indeed indicate a significant abnormality, and these results thus allowed him to receive appropriate therapy,” said Dr. Smith, who is assistant professor of radiation oncology at The University of Texas MD Anderson Cancer Center

Dr. Smith continued, “In use of medical imaging, the principal of ‘as low as reasonably achievable’ holds. This principal, abbreviated ALARA, indicates that exposure to ionizing radiation should be minimized, and that modalities that do not involve ionizing radiation, such as MRI or ultrasound, are generally preferred when reasonable.

Nevertheless, in many medical situations, exposure to low levels of ionizing radiation from diagnostic exams is vitally important and saves countless lives every year. This study helps to put the meaningful benefit of ionizing radiation in context with the small associated risks."

This research was published December 18 in the journal Radiology. No author disclosed financial relationships related to the topic of this study.