Spread of tumor microenvironment contributes to colonic obstruction through subperitoneal fibroblast activation in colon cancer

Pathology and Prognosis of Colonic Adenocarcinomas With Intermediate Primary Tumor Stage Between pT2 and pT3

CONTEXT.—

Primary tumor stage (pT) is an important prognostic indicator in colonic adenocarcinomas; however, cases that have no muscle fibers beyond the advancing tumor edge but also show no extension beyond the apparent outer border of muscularis propria (termed pT2int), have not been previously studied.

OBJECTIVE.—

To address the clinicopathologic characteristics and prognosis of pT2int tumors.

DESIGN.—

We recharacterized 168 colon carcinomas and compared pT2int cases to bona fide pT2 and pT3 tumors.

RESULTS.—

In side-by-side analysis, 21 pT2int cases diverged from 29 pT2 tumors only in terms of larger size (P = .03), but they were less likely to show high-grade (P = .03), lymphovascular (P < .001), and extramural venous invasion (P = .04); discontinuous tumor deposits (P = .02); lymph node involvement (P = .001); and advanced stage (P = .001), compared with 118 pT3 tumors. Combining pT2int with pT2 cases (versus pT3) was a better independent predictor of negative lymph nodes in multivariate analysis (P = .04; odds ratio [OR], 3.96; CI, 1.09-14.42) and absent distant metastasis in univariate analysis (P = .04), compared with sorting pT2int with pT3 cases (versus pT2). Proportional hazards regression showed that pT2 and pT2int cases together were associated with better disease-free survival compared with pT3 tumors (P = .04; OR, 3.65; CI, 1.05-12.70). Kaplan-Meier analysis demonstrated that when pT2int were grouped with pT2 tumors, they were significantly less likely to show disease progression compared with pT3 (P = .002; log-rank test) and showed a trend toward better disease-specific survival (P = .06), during a mean patient follow-up of 44.9 months.

CONCLUSIONS.—

These data support the conclusion that pT2int carcinomas have clinicopathologic characteristics and are associated with patient outcomes more closely aligned with pT2 rather than pT3 tumors.

Special cancer microenvironment in human colonic cancer: Concept of cancer microenvironment formed by peritoneal invasion (CMPI) and implication of subperitoneal fibroblast in cancer progression

Clinical outcomes of colorectal cancer are influenced not by tumor size, but by spread into the bowel wall. Although assessment of serosal involvement is an important pathological feature for classification of colon cancer, its diagnostic consistency has been questioned. Using elastic staining, we assessed elastic laminal invasion (ELI) for more objective stratification of deep tumor invasion around the peritoneal surface. In addition, pathological characteristic features of marked tumor budding, fibrosis, and macrophage infiltration in the tumor area with ELI was elucidated. This characteristic tumor area was termed cancer microenvironment formed by peritoneal elastic laminal invasion (CMPI). We elucidated histoanatomical layer-dependent heterogeneity of fibroblast in colonic tissue. Furthermore, subperitoneal fibroblasts (SPFs) play a crucial role in tumor progression and metastasis in CMPI. Our ELI and CMPI concept contributes not only to objective pathological diagnosis, but also sheds light on biological research of special cancer microenvironments detectable in human colorectal cancers. Herein, we describe the diagnostic utility of ELI and morphological alteration in advanced colorectal cancers to determine the phenomenon that occurs when tumors invade around the peritoneal surface. Next, biological research of CMPI is reviewed to stress the importance of pathological research to establish new biological concepts.

Gene expression profile in the activation of subperitoneal fibroblasts reflects prognosis of patients with colon cancer

Tumors can create a heterogenetic tumor microenvironment. We recently identified the pathologically unique cancer microenvironment formed by peritoneal invasion (CMPI), and revealed that subperitoneal fibroblasts (SPFs) within peritoneal tissue play a crucial role in tumor progression through their interaction with cancer cells. Therefore, the genes in SPFs altered by cancer stimulation may include some biologically important factors associated with patient prognosis. In this study, we aimed to identify new biomarkers using genes specifically upregulated in SPFs by cancer-cell-conditioned medium (CCCM) stimulation (SPFs CCCM response genes; SCR genes) in colon cancer (CC). We constructed two frameworks using SCR gene data: a publicly released microarray dataset, and validation cases with freshly frozen CC samples to identify genes related to short recurrence-free survival (RFS). In the first framework, we selected differentially expressed genes between the high and low SCR gene expression groups. In the second framework, genes significantly related to short RFS were selected by univariate analysis using all SCR genes, and multivariate analysis was performed to select robust genes associated with short RFS. We identified CTGF, CALD1, INHBA and TAGLN in the first framework, and PDLIM5, MAGI1, SPTBN1 and TAGLN in the second framework. Among these seven genes, high expression of three genes (CALD1, TAGLN and SPTBN1) showed a poor prognosis in our validation cases. In a public microarray dataset, SCR gene expression was associated with the expression of ECM component, EMT, and M2-macrophage associated genes, which was concordant with the pathological features of CMPI. Thus, we successfully identified new prognostic factors.