Colorectal Cancer Survivors Face Increased Risk of Developing Subsequent Cancers of Different Types
According to a new study, colorectal cancer survivors face an increased risk of developing subsequent primary cancers, particularly second colorectal cancers and small intestinal cancers. These findings, published online in Cancer, may help in the development of screening guidelines for patients with a history of colorectal cancer.
Studies have found that colorectal cancer survivors have a greater risk of developing another cancer compared with the general population. Amanda Phipps, PhD, MPH, of the University of Washington and Fred Hutchinson Cancer Research Center in Seattle, and colleagues looked to see whether that increased risk differed for people depending on where their past cancer was located within the colon or rectum. “To our knowledge, this is the first study to look at risk of second cancer according to the specific anatomic subsite of a prior colorectal cancer,” said Dr. Phipps. The research team also looked at whether there were certain kinds of cancer for which colorectal cancer survivors had a particularly increased risk.
Study Details
The investigators analyzed information from 12 Surveillance, Epidemiology, and End Results (SEER) cancer registries on people diagnosed with colorectal cancer between 1992 and 2009. The majority of patients with first primary colorectal cancer were male (54%), age 60 to 79 (67%), and non-Hispanic white (69%). The proportion of cases with these attributes was greater among those patients who subsequently developed a second primary cancer.
Individuals with a history of colorectal cancer had a 15% higher risk of developing a second cancer of any type than people in the general population, with a standardized incidence ratio of 1.15 (95% confidence interval = 1.13–1.16). Those whose past cancers were located in the transverse to descending regions of the colon experienced the greatest increased risk for cancer overall (about a 30% increased risk) and for a second colorectal cancer (a two- to threefold increased risk).
Elevated Risk of Noncolorectal Cancer
Colorectal cancer survivors’ risk of small intestinal cancer was particularly elevated—with a more than fourfold increased risk compared to the general population—regardless of where in the colon or rectum the cancer was located. There was also a significantly elevated risk of second primary cancer of the lung, bladder, kidney, stomach, and endometrium.
According to the study authors, it is possible that the increased risk of second primary small intestinal, stomach, bladder, and lung cancer could be a result of the shared origin of the endoderm-derived epithelia at these sites—a hypothesis that could also explain why the investigators observed no increased risk of leukemia or lymphoma after colorectal cancer.
“In the long term, these findings may be useful in guiding strategies for cancer screening and surveillance after a first colorectal cancer diagnosis,” said Dr. Phipps.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
