Adenoma of colorectal laterally spreading tumor non-granular type with biological phenotypic features similar to cancer.

Background and AimColorectal laterally spreading tumors (LSTs) are morphologically subdivided into granular (LST-G) and nongranular (LST-NG) categories. We aimed to elucidate the differences in oncogenic characteristics between the two types. MethodsLaterally spreading tumors resected by endoscopic submucosal dissection and surgery from March 2009 to May 2017 were examined for p53 positivity, Ki-67 labeling index (LI), microvessel density, degree of fibrosis, intensities of inducible nitric oxide synthase (iNOS) and nitrotyrosine (NT), and expression of acid mucins. We compared these factors between adenomas, noninvasive cancers, and invasive cancers, both LST-G and LST-NG. ResultsNinety-three LST-G (53 adenomas [LST-GA] and 40 cancers [LST-GC]) and 55 LST-NG (24 adenomas [LST-NGA] and 31 cancers [LST-NGC]) were evaluated. Although p53 positivity was lower in LST-GA than in LST-NGA (P<0.001), there was no difference between LST-GC and LST-NGC. Ki-67 LI was higher in LST-NGA than in LST-GA (P<0.001) and higher in LST-NGC than in LST-GC of noninvasive cancers (P<0.001). Microvessel density and degree of fibrosis were higher in LST-NGA than in LST-GA (P<0.001), and intensities of iNOS and NT were also higher in LST-NGA than in LST-GA (P<0.001). Expression of acid mucins was lower in LST-NGA than in LST-GA (P<0.001). Although there were significant differences in p53 positivity, Ki-67 LI, microvessel density, degree of fibrosis, intensities of iNOS and NT, and expression of acid mucins between LST-GA and LST-NGA, these factors were only slightly different between LST-GC and LST-NGC of invasive cancers. ConclusionsUnlike LST-GA, LST-NGA possessed phenotypic features similar to cancer.