Non-polypoid colorectal neoplasms (NP-CRNs) may be linked to a higher risk of colon cancer than the more commonly sought after colorectal polyps. Current cancer screening focuses mainly on identification of polypoid growths, however recent evidence suggests that flat NP-CRNs may develop cancer as well.

Group of researchers at the Veterans Affairs Palo Alto Health Care System led by Roy M. Soetikno, M.D., M.S. have studied 1,819 patients who underwent colonoscopy to evaluate the prevalence of NP-CRNs and their association with colorectal cancer. NP-CRNs were found in 9.35% of the population studied. When broken down into subgroups, NP-CRNs were found in 5.84% of the screening group, 15.44% of the surveillance group, and 6.01% of the population with symptoms. Prevalence of NP-CRNs with localized cancer or cancer that has spread only beneath the mucous membrane was 0.82% of the entire population studied. NP-CRNs were 10 times as likely to present with cancerous growth than polypoid lesions. Furthermore, cancerous NP-CRNs appeared to be smaller than the cancerous lesions of polypoid origin.

“In conclusion, in this population of patients at a single Veterans Affairs hospital, NP-CRNs were a relatively common finding during colonoscopy. They were more likely to contain carcinoma compared with polypoid neoplasms, independent of lesion size. Recent studies have pointed out differences in the genetic mechanisms underlying nonpolypoid and polypoid colorectal neoplasms. Future studies on NP-CRNs should further evaluate whether the diagnosis and removal of NP-CRNs has any effect on the prevention and mortality of colorectal cancer and particularly focus on their genetic and protein abnormalities,” the authors said.

Source: JAMA

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