Granular Laterally Spreading Tumors With Nodule: Rectal Location and at Least 4-cm Size Warrant en Bloc Resection

Granular laterally spreading tumors (G-LST) in the colorectum are more common than nongranular lesions, less likely to have cancer, and in general, easier to remove because of a lower prevalence of submucosal fibrosis. However, within the granular group, lesions with a discrete large nodule, often called “mixed nodular” or “GM-LST,” have a higher risk of cancer. In any LST with a substantial risk of submucosal invasive cancer (SMIC), the rationale for en bloc resection increases because patients with only superficial invasion (<1000 microns) and no other unfavorable histologic features may be able to avoid surgery after en bloc resection. 

In a multicenter Italian study, 693 lesions with GM-LST morphology were prospectively assessed. The overall risk of covert SMIC was 9.5%. Two-thirds of the lesions with covert SMIC were in the rectum, and two-thirds were ≥4 cm in size. The overall risk of covert SMIC in rectal lesions ≥4 cm in size was 22%. Thus, the number needed to treat (NNT) to remove one lesion with SMIC in that group was 5. For lesions either above the rectum or <4 cm in size, the NNT to remove one lesion with covert SMIC ranged from 13 to 20.