High polyp rate seen in young cancer survivors after abdominal radiation

Last Updated: 2016-07-27

By Anne Harding

NEW YORK (Reuters Health) - Young cancer survivors treated with abdominal radiation have a polyp prevalence similar to that seen in the general population of people 50 and older, according to new research.

"The polyp rate that we found is comparable to that in other groups for whom screening is widely accepted," Dr. David Hodgson of Princess Margaret Cancer Center in Toronto, one of the study's authors, told Reuters Health by phone.

Writing online July 13 in Gut, Dr. Hodgson and colleagues note that while young cancer survivors who have received abdominal radiation therapy (ART) are known to be at increased risk of colorectal cancer (CRC), guidance on screening for these individuals is inconsistent.

"The guidelines that recommend screening are not being fully implemented," the researcher said. "It's certain that when we look at childhood cancer survivors in their 30s and 40s that had received abdominal radiation therapy, the majority of them are not getting early initiation of colorectal cancer screening."

One reason for this, he added, is that there is no evidence showing that ART-associated CRC passes through a preclinical, screen-detectable phase.

To investigate, Dr. Hodgson and his colleagues performed early colonoscopic screening in 54 cancer survivors aged 35 to 49 who had received ART at least 10 years previously. The median age was 45, and the median time since ART was 19 years.

The study was designed to compare the rate of potentially precancerous polyps to that seen in the general population aged 40 to 50 for whom screening is not recommended (i.e., 10% or less) and people 50 and older, who generally should be screened (i.e., about 20%).

The researchers found 49 polyps in 24 patients, and 15 patients (27.8%) had polyps that were potentially precancerous. Just over half of the polyps were within or on the edge of the radiation treatment field.

Dr. Hodgson and his team note that not only was the polyp prevalence among the survivors similar to older patients for whom screening is recommended, it was also similar to the 24% seen in a study of individuals at risk for hereditary non-polyposis colon cancer who had undergone their first screening colonoscopy.

"This study provides the only prospectively gathered data lending indirect support to guideline-recommended early colorectal cancer screening initiation among survivors treated with ART," Dr. Hodgson and his colleagues write.

"Given the improbability of a randomized trial addressing this specific intervention, longitudinal studies comparing the subsequent risks of CRC among screened versus unscreened survivors may elucidate whether early removal of polyps reduces the subsequent risk of CRC, as it does in other populations with similar detection rates," they add.

SOURCE: http://bit.ly/2aaWRMT

Gut 2016.