No increased risk of colorectal cancer in older-onset IBD

Last Updated: 2016-08-17

By Marilynn Larkin

NEW YORK (Reuters Health) - A new diagnosis of inflammatory bowel disease (IBD) in individuals over age 60 does not increase the risk of developing colorectal cancer, although patients may be at increased risk for hematological cancers, say researchers based in France.

Cancer may result as a complication of IBD or its treatment (i.e., immunomodulators such as thiopurines), and the risk of malignancy "is of particular concern" in elderly-onset IBD, they note in the American Journal of Gastroenterology, online August 2.

To investigate the risks, the team reviewed French registry data from 1988 to 2006 on 844 patients who were diagnosed with IBD after age 60, including 370 with Crohn's disease (CD) and 474 with ulcerative colitis (UC). Patients were followed after diagnosis for an average of six years.

During followup, 42 CD and 56 UC patients, representing about 12% of those with IBD, developed a cancer, corresponding to an overall standardized incidence ratio (SIR) of 0.97. CD patients were about 77 years old at the time of cancer diagnosis and UC patients were approximately 75. The average time between an IBD diagnosis and a cancer diagnosis was about 6.5 years.

The team found no increased risk of colorectal cancer among the IBD patients overall (SIR=1.03), and no increased risk specifically among those with CD (SIR=1.20) or UC (SIR=0.91). Nor was there an increased risk for any other intestinal cancers, including small bowel carcinoma.

In contrast, IBD patients did have an increased risk of both malignant (SIR=2.49) and myeloproliferative disorders (SIR=2.18). CD but not UC patients were at increased risk of malignant disorders (SIR=3.09). Treatment with thiopurines was not associated with an increased risk of developing cancer (HR=0.90).

Dr. David Kelsen of Memorial Sloan Kettering Cancer Center in New York City told Reuters Health by email, "The clinical implication of this finding relates to surveillance for colorectal cancer, currently using colonoscopy as the standard of care. If there is no increased risk, then the recommended interval for colonoscopy might be the same as for the general population."

He observed, "The authors note that the median duration of IBD in the study population was relatively brief (6 years); in younger IBD patients, an increasing risk for colitis-associated bowel cancers has been noted after 8-10 years of active IBD."

"Recent studies have highlighted the difference in the spectrum of genomic alterations in colitis-associated cancers versus sporadic colorectal cancer," Dr. Kelsen continued. "It would be of interest if in a follow-up study, genomic alterations analysis could be performed on tumor samples from (this) or similar studies; the analysis might clarify whether the colorectal cancers in older IBD patients were colitis-associated cancers (CAC) or sporadic. Some current research efforts in the development in plasma-based assays for early detection of colorectal cancer may use different gene profiles in CAC versus sporadic colorectal cancers."

In an email to Reuters Health, Dr. Bincy P. Abraham, director of the Inflammatory Bowel Disease Program at Houston Methodist Hospital in Texas, also noted that the study "suggests that perhaps we don't need stringent rules in colon cancer surveillance in this (older) group of patients compared to the younger population with IBD. This could reduce the need to do more invasive monitoring such as colonoscopy every one-to-two years (for) eight years after an IBD diagnosis, which is in our recommendations for colon cancer surveillance in the general IBD population."

"However, because the group of patients in this study was protected from risk factors for intestinal cancers due to lower disease severity and lower rates of immunosuppressive medications, we would need more research in the elderly onset IBD population before suggesting lower vigilance requirements," she said.

Dr. Abraham added, "Since this study had very few patients on immunosuppressive medications, it is difficult to ascertain if there was enough power to make medication-related conclusions to the outcome. We would need additional studies of elderly IBD patients on immunomodulators and anti-TNFs to determine if medications truly did or did not play a role in cancer risk . . . . Elderly patients with IBD are generally at higher risk of developing lymphomas and other hematological cancers, and we should not necessarily blame immunosuppressive therapies for this risk."

The authors did not respond to requests for a comment.

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

Am J Gastroenterol 2016.