Serrated polyps of the colon and rectum: Remove or not?

Table 1 Probability of narrow-band imaging international colorectal endoscopic or Japan narrow-band imaging expert team type 1 lesions being sessile serrated lesions, % (95%CI)

Size	Right colon	Left colorectum	Total
≤ 5 mm	1.8 (0.2-6.2)	0.5 (0.1-1.4)	0.7 (0.2-1.5)
6-9 mm	43.8 (19.8-70.1)	13.3 (1.7-40.5)	29.0b (14.2-48.0)
≥ 10 mm	85.7 (42.1-99.6)	33.3 (0.8-90.6)	70ab (34.8-93.3)
Total	10.9d (6.3-17.4)	0.9 (0.3-2.0)	2.7 (1.7-4.0)

We histopathologically analyzed 792 narrow-band imaging international colorectal endoscopic or Japan narrow-band imaging expert team type 1 lesions. The overall probability of narrow-band imaging international colorectal endoscopic or Japan narrow-band imaging expert team type 1 lesions being sessile serrated lesions was 2.7% (21/792). This probability significantly increased as the lesion size also increased (≤ 5 mm: 0.7%; 6-9 mm: 29.0%; ≥ 10 mm: 70%) and was significantly higher in the right colon than in the left colorectum (10.9% vs 0.9%).

^aP < 0.05 vs 6-9 mm,

^bP < 0.01 vs ≤ 5 mm, and

^dP < 0.01 vs left colorectum, the χ² test or Fisher’s exact test.

Table 2 Rate of dysplasia within sessile serrated lesions, % (95%CI)

Size	Right colon	Left colorectum	Total
≤ 5 mm	0 (0-5.0)	0 (0-25.9)	0 (0-4.2)
6-9 mm	5.9 (2.2-12.5)	6.3 (0.2-30.2)	6.0a (2.4-11.9)
≥ 10 mm	14.1 (8.6-21.3)	8.3 (0.2-38.5)	13.6bc (8.4-20.4)
Total	8.3 (5.4-12.1)	5.3 (0.6-17.7)	8.0 (5.3-11.5)

We histopathologically analyzed 326 sessile serrated lesions. The overall rate of dysplasia (conventional adenoma-like dysplasia and/or serrated dysplasia) within sessile serrated lesions was 8.0% (26/326). This rate significantly increased as the lesion size increased (≤ 5 mm: 0%; 6-9 mm: 6.0%; ≥ 10 mm: 13.6%) but exhibited no significant difference between the right colon and left colorectum.

^aP < 0.05 vs ≤ 5 mm,

^bP < 0.01 vs ≤ 5 mm, and

^cP < 0.05 vs 6-9 mm, the χ² test or Fisher’s exact test.