Click B, et al. - Researchers assessed if there is a significant difference in subsequent colorectal cancer (CRC) incidence between individuals with either advanced or nonadvanced adenomas compared with those with no adenomas. Outcomes suggested an increased risk for subsequent CRC incidence in association with an identification of advanced adenoma. Nonadvanced adenoma might not have an association with increased risk.

Methods

• Researchers undertook a multicenter, prospective cohort study of participants in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer randomized clinical trial of flexible sigmoidoscopy (FSG) beginning in 1993 with follow-up for CRC incidence to 2013 across the United States.
• Participants included 154,900 men and women aged 55 to 74 years enrolled in PLCO; following their first positive FSG screening result, 15,935/154,900 underwent colonoscopy.
• December 31, 2013 was the final day of follow-up.
• They randomized enrolled participants to FSG or usual care.
• Follow-up was advised to participants who underwent FSG and had abnormal findings.
• Categorization of subsequent colonoscopy findings was performed as follows: advanced adenoma (≥1 cm, high-grade dysplasia, or tubulovillous or villous histology), nonadvanced adenoma (<1 cm without advanced histology), or no adenoma.
• CRC incidence within 15 years of the baseline colonoscopy was assessed as the primary outcome.
• CRC mortality was assessed as the secondary outcome.

Results

• Colonoscopy was performed on 15,935 participants (men, 59.7%; white, 90.7%; median age, 64 y [IQR, 61-68]).
• Initial colonoscopy revealed an advanced adenoma in 2,882 participants (18.1%), a nonadvanced adenoma in 5,068 participants (31.8%), and no adenoma in 7,985 participants (50.1%); median follow-up for CRC incidence was 12.9 years.
• Observations suggested that CRC incidence rates per 10,000 person-years of observation were 20.0 (95% CI, 15.3-24.7; n=70) for advanced adenoma, 9.1 (95% CI, 6.7-11.5; n=55) for nonadvanced adenoma, and 7.5 (95% CI, 5.8-9.7; n=71) for no adenoma.
• Significantly higher risk for developing CRC was noted in participants with advanced adenoma compared with participants with no adenoma (rate ratio [RR], 2.7 [95% CI, 1.9-3.7]; P < .001).
• No significant difference in CRC risk was noted between participants with nonadvanced adenoma compared with no adenoma (RR, 1.2 [95% CI, 0.8-1.7]; P=.30).
• Compared with participants with no adenoma, those with advanced adenoma were at markedly higher risk of CRC death (RR, 2.6 [95% CI, 1.2-5.7], P=.01); however, mortality risk in participants with nonadvanced adenoma was not significantly different (RR, 1.2 [95% CI, 0.5-2.7], P=.68).