(HealthDay News) — The location of index colorectal cancer (CRC) affects the incidence of second cancer after CRC, according to a study published online July 15 in Cancer.

Amanda I. Phipps, Ph.D., M.P.H., from the Fred Hutchinson Cancer Research Center in Seattle, and colleagues utilized 12 Surveillance, Epidemiology, and End Results cancer registries to identify patients diagnosed with a first primary CRC between 1992 and 2009. Standardized incidence ratios (SIRs) were calculated by comparing the incidence of subsequent cancers in these patients versus the incidence in the general population.

The researchers found that, compared with the general population, the cancer incidence rates were significantly higher in individuals who had a previous CRC (SIR, 1.15). The greatest increased risk overall (SIR, 1.29 to 1.33) and with respect to the risk of a second CRC (SIR, 2.53 to 3.35) was seen in individuals with an index CRC located between the transverse and descending colon.

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Regardless of the index CRC subsite, the incidence of small intestinal cancer was significantly increased (SIR, 4.31). For those with an index CRC in the proximal colon, the incidence of endometrial cancer was significantly elevated (SIR, 1.37 to 1.79).

“The results presented here confirm previous reports of an elevated cancer risk in CRC survivors relative to the general population and provide added evidence that this elevated risk differs by location of the index CRC,” the authors write.