Molecular pathogenesis of sporadic colorectal cancers

Colorectal cancer (CRC) results from the progressive accumulation of genetic and epigenetic alterations that lead to the transformation of normal colonic mucosa to adenocarcinoma. Approximately 75% of CRCs are sporadic and occur in people without genetic predisposition or family history of CRC. During the past two decades, sporadic CRCs were classified into three major groups according to frequently altered/mutated genes. These genes have been identified by linkage analyses of cancer-prone families and by individual mutation analyses of candidate genes selected on the basis of functional data. In the first half of this review, we describe the genetic pathways of sporadic CRCs and their clinicopathologic features. Recently, large-scale genome analyses have detected many infrequently mutated genes as well as a small number of frequently mutated genes. These infrequently mutated genes are likely described in a limited number of pathways. Gene-oriented models of CRC progression are being replaced by pathway-oriented models. In the second half of this review, we summarize the present knowledge of this research field and discuss its prospects.

Differential mucin phenotypes and their significance in a variation of colorectal carcinoma

AIM: To investigate mucin expression profiles in colorectal carcinoma (CRC) histological subtypes with regard to clinicopathologic variables and prognosis.

METHODS: Mucin (MUC)2 and MUC5AC expressions were assessed by immunohistochemistry for a total of 250 CRC cases that underwent surgical resection. CRCs included 63 well-to-moderately differentiated adenocarcinomas (WMDAs), 91 poorly differentiated adenocarcinomas (PDAs), 81 mucinous adenocarcinoma (MUAs), and 15 signet-ring cell carcinomas (SRCCs). MUC2 and MUC5AC were scored as positive when ≥ 25% and ≥ 1% of cancer cells were stained positive, respectively. The human mutL homolog 1 and human mutS homolog 2 expressions were assessed by immunohistochemistry in PDAs to investigate mismatch-repair (MMR) status. Tumors that did not express either of these two were considered MMR-deficient. Results were analyzed for associations with clinicopathologic variables and the prognosis in individual histological CRC subtypes.

RESULTS: MUC2-positive and MUC5AC-positive WMDA percentages were 49.2% and 30.2%, respectively. In contrast, MUC2-positive and MUC5AC-positive PDA percentages were 9.5% and 51.6%, respectively. MUC2 levels tended to decrease and MUC5AC levels tended to increase from WMDA to PDA. In 21 tumors comprising both adenoma and adenocarcinoma components in a single tumor (4 WMDAs, 7 PDAs, and 10 MUAs), MUC2 was significantly downregulated in PDA and MUC5AC was downregulated in PDA and MUA in the adenoma-carcinoma sequence. These results suggested that MUC2 levels might be associated with malignant potential and that MUC5AC expression was an early event in tumorigenesis. Despite worse prognoses than WMDA, high MUC2 expression levels were maintained in MUA (95.1%) and SRCC (71.5%), which suggested a pathogenesis for these subtypes distinct from that of WMDA. No significant associations were found between MUC2 expression and any clinicopathologic variables in any histological subtype. MUC5AC expression in PDA was closely associated with right-sided location (P = 0.017), absence of nodal metastasis (P = 0.010), low tumor node metastasis stage (P = 0.010), and MMR deficiency (P = 0.003). MUC2 expression in WMDA was a marginal prognostic factor for recurrence/metastasis-free survival (RFS) by univariate Cox analysis (P = 0.077) but not by multivariate Cox analysis (P = 0.161). MUC5AC expression in PDA was a significant prognostic factor for RFS by univariate Cox analysis (P = 0.007) but not by multivariate Cox analysis (P = 0.104). Kaplan-Meier curves and log-rank tests revealed that MUC2 expression was marginally associated with a better WMDA prognosis [P = 0.064 for RFS and P = 0.172 for overall survival (OS)] but not for PDA. In contrast, MUC5AC expression was significantly and marginally associated with a better PDA prognosis in terms of RFS and OS, respectively (P = 0.004 for RFS and P = 0.100 for OS), but not for WMDA and MUA.

CONCLUSION: Mucin core protein expression profiles and clinical significance differ according to histological CRC subtypes. This may reflect different pathogeneses for these tumors.

Sex steroid hormone receptors in bladder cancer: Usefulness in differential diagnosis and implications in histogenesis of bladder cancer

OBJECTIVE

In rare cases, differential diagnosis between bladder cancer (BC) and gynecological tract cancer (GTC) is difficult because of anatomical proximity and morphological similarity. We analyzed expression status of sex steroid hormone receptors in BC in this study. First, we investigated their usefulness as a histological marker for differential diagnosis. Second, we considered their roles in BC histogenesis.

METHODS

Estrogen receptor α (ERα) and progesterone receptor (PgR) expression was investigated by immunohistochemistry in 125 BCs obtained by transurethral resection or biopsy, then in nonneoplastic background mucosa (trigone, fundus, and dome) of 33 total cystectomy samples. They were evaluated as positive when ≥ 1% of 500 subject cells were immunoreactive with moderate or strong intensities.

RESULTS

ERα and PgR were positive in 38.4% and 3.2% of BCs, respectively, suggesting that ERα status alone could not definitely differentiate between BC and GTC. ERα expression was not significantly associated with age and sex of BC patients and histopathology of BCs. Although not significant, ERα expression was more frequent in higher grade (G1/G2 vs. G3/G4; P = 0.143) and marginally associated with advanced stage of BCs (pTis/pTa/pT1 vs. pT2/pT3, P = 0.056). ERα expression was significantly more frequent in background mucosa with ERα-positive BC (In the epithelium and stroma; both P < 0.001). ERα expression was continuously observed from normal to malignant epithelium in some cases. Although not significant, Brunn's nest or cystitis glandularis was more frequent in background mucosa with ERα-positive BC (P = 0.218). Analyses of nonneoplastic mucosa in cystectomy revealed that ERα was more frequently positive in urothelium of trigone, a predilection site for cystitis glandularis, than those of fundus and dome, with a significant difference between trigone and dome (P = 0.034). These data suggest that chronic inflammation may up-regulate ERα in the background epithelium, especially in trigone, and ERα expression in BC might be the reflection of bladder epithelium from which BC arose.

CONCLUSIONS

Usefulness of ERα was limited in differential diagnosis between BC and GTC. ERα up-regulation might not play a critical role in the development of BC because it was already noted in the background bladder mucosa.

Poorly differentiated adenocarcinoma of the colon: subsite location and clinicopathologic features

PURPOSE

Colorectal cancers of the proximal colon are characterized by good prognosis, microsatellite instability (MSI), and poor differentiation. MSI is associated with a favorable prognosis, but poorly differentiated adenocarcinomas (PDAs) have a poor prognosis. In this study, we aimed to investigate this inconsistency by analyzing the heterogeneity of PDAs.

METHODS

A total of 156 surgically resected PDAs were analyzed according to tumor subsite by morphological and immunohistochemical analyses.

RESULTS

Proximal PDAs (n = 86) were significantly associated with females, older age, cytokeratin (CK) 20 downregulation, aberrant MUC5AC expression, and MSI compared with distal PDAs (n = 70). Proximal PDAs tended to show a better overall survival rate than distal PDAs. PDAs with microsatellite stability (MSS) were suggested to progress from well- and moderately differentiated adenocarcinomas (WMDAs), but MSI PDAs typically not. MSI PDAs demonstrated a prognosis marginally better than MSS PDAs, but significantly worse than WMDAs (n = 170). Proximal MSS PDAs had a similar unfavorable prognosis but were significantly associated with females and aberrant MUC5AC expression compared with distal MSS PDAs. MSI may be predictive of prognosis only in proximal PDAs, because nearly all distal PDAs were MSS. In contrast, CK20 downregulation was significantly associated with better prognosis in both subsites.

CONCLUSIONS

Proximal PDAs had a better prognosis than distal PDAs due to a higher incidence of MSI PDAs, whose prognosis was significantly worse than WMDAs. Female and MUC5AC expression were characteristic of proximal PDAs independent of MSI. Subsite-specific features of PDAs may serve for subclassification and predicting prognosis.

Effect and limitation of neoadjuvant chemotherapy for pancreatic ductal adenocarcinoma: consideration from a new perspective

BACKGROUND

Effect of neoadjuvant chemotherapy (NAC) for pancreatic ductal adenocarcinoma (PDAC) has remained under investigation. We investigated its effect from a unique perspective and discussed its application.

PATIENTS AND METHODS

We retrospecively analyzed consecutive 131 PDAC patients who underwent pancreatoduodenectomy and distal pancreatectomy. Clinicopathologic data at surgery and postoperative prognosis were compared between patients who underwent upfront surgery (UFS) (n = 64) and those who received NAC (n = 67), of which 62 (92.5%) received gemcitabine plus S-1 (GS). The GS regimen resulted in about 15% of partial response and 85% of stable disease in a previous study which analyzed a subset of this study subjects.

RESULTS

Tumor size was marginally smaller, degree of nodal metastasis and rate of distant metastasis were significantly lower, and pathologic stage was significantly lower in the NAC group than in the UFS group. In contrast, significant differences were not observed in histopathologic features such as vessel and perineural invasions and differentiation grade. Notably, disease-free and overall survivals were similar between the two groups adjusted for the pathologic stage, suggesting that effects of NAC, including macroscopically undetectable ones such as control of micro-metastasis and devitalizing tumor cells, may not be remarkable in the majority of PDAC, at least with respect to the GS regimen.

CONCLUSIONS

NAC may be useful in downstaging and improving prognosis in a small subset of tumors. However, postoperative prognosis may be determined at the pathologic stage of resected specimen with or without NAC. Therefore, NAC may be applicable to borderline resectable and locally advanced PDAC for enabling surgical resection, but UFS would be desirable for primary resectable PDAC.

Clinical impacts of resection margin status and clinicopathologic parameters on pancreatic ductal adenocarcinoma

Background

The clinical relevance of pancreatic intraepithelial neoplasia (PanIN) at the resection margin of pancreatic ductal adenocarcinoma remains unknown. We aimed to investigate its clinical impact at the pancreatic transection margin (PTM) and, based on the result, determine the prognostic values of the resection margin status and other clinicopathologic parameters.

Patients and methods

We retrospectively analyzed 122 consecutive patients who underwent pancreatoduodenectomy or distal pancreatectomy between 2006 and 2018. Pathologic slides were reviewed and survival data were retrieved from institutional databases. Associations between two variables were investigated by Fisher’s exact test. Survival curves were generated by the Kaplan-Meier method. Prognostic factors were assessed using Cox regression analysis.

Results

Tumors were resected without leaving macroscopic remnants. The median follow-up period after surgery was 524.5 days. Cancer-related death (n = 72) was marginally and significantly associated with local recurrence (n = 22) and distant metastasis (n = 79), respectively. Local recurrence and distant metastasis occurred independently. After excluding cases with invasive cancer at any other margin, PanIN-2 or PanIN-3 (n = 21) at the PTM did not adversely affect prognoses compared with normal mucosa or PanIN-1 (n = 57) with statistical significance. R0 resection (n = 78), which is invasive cancer-free at all resection margins, showed somewhat better local recurrence-free and overall survivals as compared with R1 resection (n = 44), which involves invasive cancer at any resection margin, but the differences did not reach statistical significance. In contrast, differentiation grade and nodal metastasis were significant predictors of distant metastasis, and tumor location and differentiation grade were significant predictors of cancer-related death. Although there was no significant difference in differentiation grade between the head cancer and the body or tail cancer, nodal metastasis was significantly more frequent in the former than in the latter.

Conclusions

PanINs at the PTM did not adversely affect prognosis and R0 resection was not found to be a significant prognostic factor. Differentiation grade might be an indicator of occult metastasis and affect patients’ overall survival through distant metastasis. In addition to successful surgical procedures, tumor biology may be even more important as a predictor of postoperative prognosis.

Expression of cytokeratin 20 indicates invasive histological phenotype in poorly differentiated colorectal adenocarcinoma

BACKGROUND/AIM

Cytokeratin (CK) 20 expression is an independent prognostic factor of poorly differentiated adenocarcinoma (PDA) of the colon and rectum. We aimed to investigate the mechanism of its involvement through a clinicopathological study.

PATIENTS AND METHODS

We analyzed 156 surgically resected PDAs, which were sub-classified as solid type (Por1) showing expansive growth, or non-solid type (Por2) showing infiltrative growth. Associations of CK20 expression with morphological features and molecular markers were analyzed.

RESULTS

CK20(+) PDA (n=91) was associated with more advanced disease stage and unfavorable prognosis compared with CK20(-) PDA (n=65). Pathologically, CK20(+) PDA was significantly associated with p53 overexpression, Por2, abundant fibrous stroma, and stepwise de-differentiation, while CK20(-) PDA was significantly associated with mismatch repair deficiency, Por1, sparse fibrous stroma, and de novo histogenesis.

CONCLUSION

CK20 expression in PDA is closely associated with invasive histological features, providing prognostic significance, and may also point to a specific histogenetic pathway.

Risk stratification for predicting postoperative recurrence of gastric cancer by grade of venous invasion

BACKGROUND

Venous invasion (VI) in pathological examination of surgically resected gastric cancer (GC) may predict postoperative recurrence, but there are no objective criteria for VI grading.

METHODS

157 GC patients (pathological stages I 82, II 34, and III 41) who underwent surgery with curative intent were analyzed. VI was graded in pathological examination by elastica van Gieson staining based on the number of VIs per glass slide as follows: v0, 0; v1, 1-3; v2, 4-6; and v3, ≥ 7. Filling-type invasion in veins with a minor axis of ≥ 1 mm increased the grade by 1. The association of VI grade with prognosis was statistically analyzed.

RESULTS

Recurrence increased with VI grade (v0 1.5%, v1 29.6%, v2 41.7%, v3 78.6%). VI grade as well as pathological (p) tumor, node, metastasis (TNM) stage was a significant recurrence predictor by the multivariate Cox analysis. VI grade was implicated in hematogenous and peritoneal recurrences independent of pTNM stage but not in nodal recurrence. GC was then divided into two tiers, without indication of adjuvant chemotherapy (AC) (pStage I, pT1 and pT3N0) and with AC indication (pStages remaining II/III), based on the ACTS-GC trial, which is common in Japan and East Asia. VI grade was a significant recurrence predictor in both tiers. v2/v3 revealed a significantly worse recurrence-free survival (RFS) than v0/v1 in GC without AC indication. v0/v1 exhibited RFS rate exceeding 95% even after 5 years but that of v2/v3 fell around 70% within one year postoperatively, suggesting that AC may be considered for this tier with v2/v3. GC with AC indication exhibited dismal RFS according to the VI grade. RFS rate fell below 80% within one year postoperatively when VI was positive, while recurrence was not observed in v0, which was, however, rare in this tier (10.9%). Differentiation grade did not significantly affect postoperative prognosis in both tiers.

CONCLUSIONS

VI grade was a significant predictor of postoperative GC recurrence irrespective of the AC indication based on the ACTS-GC study and this VI grading system could be applied in future studies of adjuvant therapy in GC presently deemed without AC indication in Japan.

The Impact of Venous Invasion on the Postoperative Recurrence of pT1-3N0cM0 Gastric Cancer

The impact of venous invasion (VI) on postoperative recurrence in pathological (p)T1-3N0 clinical (c)M0 gastric cancer (GC) remains unclear. We investigated the association of VI grade with prognosis in 94 (78 stage I and 16 stage IIA) patients. VI was graded during pathological examinations based on the number of VIs per glass slide as follows: v0, 0; v1, 1-3; v2, 4-6; and v3, ≥7. Filling-type invasion in veins with a minor axis of ≥1 mm increased VI grade by 1. Four (4.3%) patients experienced recurrence. Recurrence increased with pT (pT1, 0.0%; pT2, 11.1%; pT3, 18.8%) and VI grade (v0, 0.0%; v1, 3.7%, v2, 14.3%; and v3, 40.0%). Recurrence was significantly more frequent in pT3 than pT1 and in v2 + v3 than v0 (p = 0.006 and 0.005, respectively). Kaplan-Meier curve analyses demonstrated a significant decrease in recurrence-free survival according to pT (p = 0.0021) and VI grade (p < 0.0001). Multivariate Cox analysis revealed a significant association of VI grade with recurrence (p = 0.049). These results suggest that VI grade is a potential recurrence predictor for pT1-3N0cM0 GC. No recurrence can be expected in cases with pT1 or VI grade v0. Adjuvant therapy might be considered for pT3 or VI grade v2 + v3.

An unusual cytological presentation of solid pseudopapillary neoplasm of the pancreas mimicking adenoid cystic carcinoma: a case report and literature review

Endoscopic ultrasound-guided fine-needle aspiration has become the common procedure for the diagnosis of pancreatic mass, and cytological examination is usually the first approach. Solid pseudopapillary neoplasm (SPN) cytologically represents papillary structures of branching capillaries surrounded by discohesive neoplastic cells. However, it may present various degrees of tissue degeneration, causing diagnostic challenges. Here, we report a 21-year-old female who had a 2-cm-sized mass in the pancreas head. Cytological examination revealed clumps of small round/oval cells that represented microcystic configurations with mucus, mimicking adenoid cystic carcinoma or mucinous adenocarcinoma. Cercariform cells, nuclear grooves/folding, and cytoplasmic vacuoles were not observed. Histopathological examination revealed confluent small glandular structures containing acidic mucus. The tumor cells were positively stained for β-catenin, CD10, and CD56, and negative for chromogranin A and E-cadherin, suggesting SPN, micropseudocystic variant. This variant has been scarcely described, but we should recognize it for accurate cytological triage of pancreatic tumors.

Risk stratification for predicting postoperative recurrence/metastasis of colorectal cancer by grade of venous invasion coupled with histological subtype

Background

Colorectal cancer (CRC) consists of several histological subtypes that greatly affect prognosis. Venous invasion (VI) has been implicated in the postoperative recurrence of CRC, but the relationship between the VI grade and postoperative recurrence in each histological subtype has not been clarified thus far.

Methods

A total of 323 CRCs without distant metastasis at surgery (pathologic stage III or lower), including 152 well-to-moderately differentiated adenocarcinomas (WMDAs), 98 poorly differentiated adenocarcinomas (PDAs), and 64 mucinous adenocarcinomas (MUAs), were analyzed. They were routinely processed pathologically, and VI was graded as follows irrespective of location by elastica van Gieson staining: v0 (none), no venous invasion; v1 (mild), 1–3 invasions per glass slide; v2 (moderate), 4–6 invasions per glass slide; and v3 (severe), ≥ 7 invasions per glass slide. Filling-type invasion in veins with a minor axis of ≥ 1 mm increased the grade by 1. The association of VI grade with prognosis was statistically analyzed.

Results

All recurrences occurred as distant metastases. Recurrence increased with VI grade in WMDA (v0 11.8%, v1 15.8%, v2 73.9%, v3 75.0%) and MUA (v0 15.2%, v1 30.8%, v2 40.0%). The recurrence rate was relatively high in PDA even with v0 and increased with VI grade (v0 27.8%, v1 32.7%, v2 33.3%, v3 60.0%). VI grade was a significant predictor of recurrence in WMDA but not in PDA and MUA by multivariate analysis. In node-negative (stage II or lower) CRC, the recurrence-free survival (RFS) rate exceeded 90% in v0 and v1 WMDA until postoperative day (POD) 2100 and v0 MUA until POD 1600 but fell below 80% in the other settings by POD 1000. In node-positive (stage III) CRC, the RFS rate fell below 80% in all histological subtypes by POD 1000.

Conclusions

VI grade v1 had a similar recurrence rate and RFS as grade v0 and may not warrant adjuvant chemotherapy in node-negative (stage II or lower) WMDA. In addition to node-positive (stage III) CRC, adjuvant chemotherapy may be indicated for node-negative (stage II or lower) CRC when it is WMDA with VI grade v2 or v3, MUA with VI, or PDA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02163-7.