Synchronous colon carcinomas: molecular-genetic evidence for multicentricity

A template to quantify the location and density of CD3 + and CD8 + tumor-infiltrating lymphocytes in colon cancer by digital pathology on whole slides for an objective, standardized immune score assessment

BACKGROUND

In colon cancer, the location and density of tumor-infiltrating lymphocytes (TILs) can classify patients into low and high-risk groups for prognostication. While a commercially available 'Immunoscore®' exists, the incurred expenses and copyrights may prevent universal use. The aim of this study was to develop a robust and objective quantification method of TILs in colon cancer.

METHODS

A consecutive, unselected series of specimens from patients with colon cancer were available for immunohistochemistry and assessment of TILs by automated digital pathology. CD3 + and CD8 + cells at the invasive margin and in tumor center were assessed on consecutive sections using automated digital pathology and image analysis software (Visiopharm®). An algorithm template for whole slide assessment, generated cell counts per square millimeters (cells/mm2), from which the immune score was calculated using distribution volumes. Furthermore, immune score was compared with clinical and histopathological characteristics to confirm its relevance.

RESULTS

Based on the quantified TILs numbers by digital image analyses, patients were classified into low (n = 83, 69.7%), intermediate (n = 14, 11.8%) and high (n = 22, 18.5%) immune score groups. High immune score was associated with stage I-II tumors (p = 0.017) and a higher prevalence of microsatellite instable (MSI) tumors (p = 0.030). MSI tumors had a significantly higher numbers of CD3 + TILs in the invasive margin and CD8 + TILs in both tumor center and invasive margin, compared to microsatellite stable (MSS) tumors.

CONCLUSION

A digital template to quantify an easy-to-use immune score corresponds with clinicopathological features and MSI in colon cancer.

Whole exome sequencing reveals intertumor heterogeneity and distinct genetic origins of sporadic synchronous colorectal cancer

Sporadic synchronous colorectal cancer (CRC) refers to more than one primary tumor detected in a single patient at the time of the first diagnosis without predisposition of cancer development. Given the same genetic and microenvironment they raise, sporadic synchronous CRC is a unique model to study CRC tumorigenesis. We performed whole exome sequencing in 32 fresh frozen tumor lesions from 15 patients with sporadic synchronous CRC to compare their genetic alterations. This approach identified ubiquitously mutated genes in the range from 0.34% to 4.22% and from 0.8% to 7.0% in non-hypermutated tumors and hypermutated tumors, respectively, in a single patient. We show that both ubiquitously mutated genes and candidate cancer genes from different tumors in the same patient mutated at different sites. Consistently, obvious differences in somatic copy number variations (SCNV) were found in most patients with non-hypermutated tumor lesions, which had ubiquitous copy number amplification rates ranging from 0% to 8.8% and ubiquitous copy number deletion rates ranging from 0% to 8.2%. Hypermutated lesions were nearly diploid with 0% to 18.8% common copy number aberrations. Accordingly, clonal structures, altered signaling pathways and druggable genes in a single patient with synchronous CRC varied significantly. Taken together, the disparate SCNVs and mutations in synchronous CRC supported the field effect theory of tumorigenesis. Moreover, the intertumor heterogeneity of synchronous CRCs implies that analysis of all tumor lesions from the same patient is necessary for appropriate clinical treatment decisions.

Synchronous trifocal colorectal cancer

Synchronous colorectal cancers (SCRCs) have been increasingly diagnosed due to emerging diagnostic modalities. The presence of three or more synchronous colorectal cancers has, however, only rarely been reported. A 76-year-old white man presented for management of two concurrent colorectal adenocarcinomas in the left colon evidenced on total colonoscopy. Preoperative abdominal ultrasonography and thoracoabdominal computed tomography were negative for metastatic disease. The patient underwent an elective left hemicolectomy. The pathology report ultimately showed the presence of three moderately differentiated, distinct colorectal cancers. The patient experienced an uneventful recovery.

Differential diagnosis between primary lung squamous cell carcinoma and pulmonary metastasis of head and neck squamous cell carcinoma

Differentiation between lung squamous cell carcinoma and pulmonary metastasis of head and neck squamous cell carcinoma is clinically important because the prognoses and therapeutic options are considerably different. However, the clinical, pathological, and immunohistochemical diagnostic methods have not yet been fully established. Although various molecular methods have been developed, they have not yet been practically applied. A combined approach involving molecular and immunohistochemical analysis, such as one that uses antibodies selected on the basis of comprehensive genetic analysis results, may be effective. We suggest a new diagnostic criteria using the clinical characteristics and the result of immunohistochemical analysis. However, there are two underlying problems in the development of new diagnostic methods: tumor heterogeneity and determination of the diagnostic accuracy.

RAS mutations vary between lesions in synchronous primary colorectal cancer: testing only one lesion is not sufficient to guide anti-EGFR treatment decisions

Introduction

Mutations in KRAS and NRAS genes are negative predictors of anti-EGFR therapies response in metastatic colorectal cancer. There are few reports on RAS testing in synchronous primary colorectal cancer (SP-CRC) and a lack of recommendations on which tissue should be tested for the mutation in this disease. This study analyzed the RAS status of both lesions in SP-CRC patients and in their metastasis.

Materials and methods

DNA was obtained from formalin-fixed-paraffin-embedded tissue, and mutations were analyzed by pyrosequencing.

Results

RAS status was heterogeneous in 6 (75%) of 8 SP-CRC patients between primary lesions. Five showed heterogeneity regarding RAS mutational status, and from these, four presented with metastasis: 3 cases (75%) had WT metastatic tissue, and 1 case (25%) had mutated metastatic tissue. One patient showed divergence regarding RAS mutation type.

Discussion

RAS mutations vary significantly between SP-CRC lesions, and the status of the metastasis is unpredictable. Testing for RAS mutations in only 1 of the primary lesions can misguide clinical decisions and hind the predictive potential of anti-EGFR treatment. A more appropriate approach in metastatic SP-CRC is to test the metastatic tissue or both primary lesions for providing more accurate mutation scenery and support more assertive clinical decisions.

Synchronous colorectal cancer: Clinical, pathological and molecular implications

Synchronous colorectal carcinoma refers to more than one primary colorectal carcinoma detected in a single patient at initial presentation. A literature review has shown that the prevalence of the disease is approximately 3.5% of all colorectal carcinomas. This disease has a male to female ratio of 1.8:1. The mean age at presentation of patients with synchronous colorectal cancer is in the early half of the seventh decade. Patients with inflammatory bowel diseases (ulcerative colitis and Crohn’s disease), hereditary non-polyposis colorectal cancer, familial adenomatous polyposis and serrated polyps/hyperplastic polyposis are known to have a higher risk of synchronous colorectal carcinoma. These predisposing factors account for slightly more than 10% of synchronous colorectal carcinomas. Synchronous colorectal carcinoma is more common in the right colon when compared to solitary colorectal cancer. On pathological examination, some synchronous colorectal carcinomas are mucinous adenocarcinomas. They are usually associated with adenomas and metachronous colorectal carcinomas. Most of the patients with synchronous colorectal cancer have two carcinomas but up to six have been reported in one patient. Patients with synchronous colorectal carcinoma have a higher proportion of microsatellite instability cancer than patients with a solitary colorectal carcinoma. Also, limited data have revealed that in many synchronous colorectal carcinomas, carcinomas in the same patient have different patterns of microsatellite instability status, p53 mutation and K-ras mutation. Overall, the prognosis of patients with synchronous colorectal carcinoma is not significantly different from that in patients with solitary colorectal carcinoma, although a marginally better prognosis has been reported in patients with synchronous colorectal carcinoma in some series. A different management approach and long-term clinical follow-up are recommended for some patients with synchronous colorectal cancer.

Epigenetic profiling of synchronous colorectal neoplasias by quantitative DNA methylation analysis

Transcriptional inactivation of tumor-suppressor genes by promoter CpG island methylation is thought to be an important mechanism in human carcinogenesis. The CpG island methylator phenotype (CIMP) with extensive promoter methylation appears to be a distinct epigenetic subtype of colorectal carcinoma. Most previous studies on CpG island methylation in colorectal carcinoma used methylation-specific PCR, which may detect low levels of DNA methylation with little or no biological significance. In contrast, quantitative DNA methylation assays have been shown to provide useful information beyond that which can be achieved with methylation-specific PCR. Synchronous neoplasias provide a unique model for investigators to examine molecular alterations in multistep tumorigenesis within one individual. However, no study to date has quantified DNA methylation of CIMP-specific promoters in synchronous colorectal neoplasias. Utilizing real-time PCR (MethyLight), we quantified DNA methylation in five CIMP-specific gene promoters [CACNA1G (calcium channel, voltage-dependent, T type alpha-1G subunit), CDKN2A (p16/INK4A), CRABP1 (cellular retinoic acid binding protein-1), MLH1 and NEUROG1 (neurogenin 1)] and MGMT in six synchronous carcinoma pairs (12 carcinomas) and eight synchronous carcinoma and adenoma pairs (16 tumors). We found that while some synchronous tumor pairs showed discordant promoter methylation patterns, other tumor pairs showed similar, but not exactly identical, patterns of promoter methylation. All but two pairs showed concordant patterns of CIMP status (CIMP positive vs CIMP negative) (P = 0.05 in cancer pairs). BRAF mutations were present in only CIMP-positive tumors. A high degree of microsatellite instability (MSI-H) was observed in both CIMP-positive and CIMP-negative tumors. KRAS mutations were not concordant in any synchronous neoplasia pair. In conclusion, epigenetic alterations at CIMP-specific promoter CpG islands in synchronous colorectal neoplasias likely have both random and nonrandom components.

Gastrointestinal, Pancreatic, and Hepatic Cancer During Pregnancy

Pregnancy affects the clinical presentation, evaluation, treatment, and prognosis of patients with gastrointestinal cancer. Pregnant patients may present with advanced gastrointestinal cancer as a result of delayed diagnosis, in part because of difficulty differentiating signs and symptoms of cancer from signs and symptoms of normal pregnancy. The approach to cancer surgery and chemotherapy must be modified in pregnant patients to minimize fetal and maternal risks. Because of these factors, women who develop gastrointestinal cancers during pregnancy seem to have a poor prognosis. This article focuses on cancers of the colon, stomach, pancreas, and liver that occur during pregnancy.

A Molecular Genetic and Statistical Approach for the Diagnosis of Dual-Site Cancers

BACKGROUND

Concurrent tumors can be synchronous, independently derived, non-metastatic tumors or metastatic tumors. The prognosis and clinical management of patients with these different concurrent tumor types are different.

METHODS

DNA from normal and tumor tissues of 62 patients with synchronous endometrial and ovarian, bilateral ovarian, or endometrial and bilateral ovarian tumors was analyzed for loss of heterozygosity and microsatellite instability using eight polymorphic microsatellite markers at loci frequently deleted in ovarian and/or endometrial cancers. A statistical algorithm was designed to assess the clonal relationship between the tumors.

RESULTS

The original histopathology reports classified 26 (42%) case patients with single primary tumors and related metastatic lesions and 21 (34%) with independent primary tumors; 15 (24%) were unclassified. Genetic data identified 35 (56%) case patients with single primary tumors and related metastatic lesions, 18 (29%) with independent primary tumors, and nine (15%) that could not be typed. Excluding case patients with histopathology reports for which a clonal relationship was uncertain or was not reported, there was 53% concordance between genetic and histopathology diagnoses. Increasing the stringency of the statistical analysis increased the number of uncertain diagnoses but did not affect the proportion of discordant genetic and histologic diagnoses.

CONCLUSIONS

We have developed a rapid and robust combined genetic and statistical method to establish whether multiple tumors from the same patient represent distinct primary tumors or whether they are clonally related and therefore metastatic. For the majority of case patients, histopathology reports and genetic analyses were in agreement and diagnostic confidence was improved. Importantly, in approximately one-fourth of all case patients, genetic and histopathologic analyses suggested alternative diagnoses. The results suggest that genetic analysis has implications for clinical management and can be performed rapidly as a diagnostic test with paraffin-embedded tissues.

Colon cancer during pregnancy

The medical community should become mobilized to diagnose colon cancer earlier in pregnancy to improve prognosis. The primary care physician or obstetrician should refer the pregnant patient with significant gastrointestinal complaints to the gastroenterologist for evaluation. Likewise, the gastroenterologist should be prepared to perform sigmoidoscopy, preferably without endoscopic medications, for significant lower gastrointestinal symptoms such as persistent rectal bleeding. Sigmoidoscopy is particularly sensitive in identifying colon cancer in pregnant patients because their cancers are usually distal and within reach of the sigmoidoscope.

The role of hMLH1 methylation in the development of synchronous sporadic colorectal carcinomas

PURPOSE

AB. B. subset of sporadic colorectal carcinomas show microsatellite instability, usually as a result of biallelic hMLH1 gene promoter methylation. Synchronous tumors occur in up to 5 percent of patients with colorectal cancer, but their cause is poorly understood. We hypothesized that in the setting of sporadic microsatellite instability cancers, synchronicity may reflect a global predisposition of colorectal epithelium toward tumor development because of gene hypermethylation.

METHODS

We identified 14 individuals with 33 synchronous cancers from a series of 362 patients with 381 sporadic colorectal cancers. We then analyzed the synchronous lesions for microsatellite status, hMLH1 protein expression, and hMLH1 promoter methylation.

RESULTS

Seven of 33 synchronous tumors (21 percent) showed microsatellite instability, compared with 36 of 348 solitary tumors (10.3 percent, P = 0.06). The 14 patients with synchronous tumors were significantly older than those with solitary tumors (mean age 79.4 vs. 68.2 years, P = 0.01), and 5 of these patients had at least one microsatellite instability tumor. However, only one patient harbored synchronous tumors that were all of the microsatellite instability type. Methylation of the hMLH1 promoter was seen in 9 synchronous cancers from 27 assessable lesions in 7 patients and was associated with microsatellite instability (P = 0.01), right-sidedness (P = 0.01), and loss of expression of hMLH1 (P = 0.03). Only one case showed methylation in all synchronous tumors, whereas in five cases synchronous tumors showed different methylation status within the one individual.

CONCLUSION

Our data suggest that synchronous tumors arise as independent events and that the slightly greater frequency of synchronous tumors in individuals with microsatellite instability cancers is likely to be a chance event reflecting the older age of these individuals rather than arising from a predisposition toward cancer as a result of global hypermethylation of colorectal epithelium.

Discordance of p53 mutations of synchronous colorectal carcinomas

It is unclear whether synchronous multiple tumors arise from multicentric or monoclonal origins. To verify the multicentric origin of synchronous colorectal carcinomas at a genetic level, immunohistochemical and molecular techniques were used to determine the p53 alterations in individual lesions of synchronous colorectal carcinomas. This study was based on a total of 32 colorectal tumors from 16 patients. Twenty-one of the 32 (66%) advanced tumors examined had positive staining for p53. Single-strand conformation polymorphism and polymerase chain reaction direct sequencing were carried out for exons 5 to 8 of p53. All cases had p53 mutations in one or more tumors of synchronous lesions. In nine patients in this series, individual lesions were found to carry a different mutated codon of the p53 gene. In the other seven patients, a p53 mutation was found in one tumor but not in another. These results indicate discordance of the mutation pattern of p53 in individual lesions of multiple colorectal carcinomas and support the idea that most synchronous colorectal carcinomas are genetically distinguishable and are multicentric in origin. We also confirmed the high frequency of p53 mutations in left-sided (71%) and rectal (91%) carcinomas, rather than right-sided (43%; P = .04) carcinomas, suggesting that the molecular mechanism of synchronous colorectal carcinomas might differ between right- and left-sided tumors in the same patient.

Overexpression of CD44: a useful independent predictor of prognosis in patients with colorectal carcinomas

BACKGROUND

The goal was to investigate the potential correlation between overexpression of CD44, high microvessel count (MVC), and p21ras with length of relapse-free and overall survival in patients with colorectal adenocarcinomas.

METHODS

CD44, factor VIII-related antigen (FVIII-RA), and p21ras were localized immunohistochemically in patients with colorectal adenomatous polyps (n = 8) and adenocarcinomas (n = 98). The correlation between the expression of CD44, MVC in the areas with highest density, and p21ras with relapse-free and overall survival time was investigated. Data were analyzed statistically using univariate and multivariate systems.

RESULTS

In patients with adenomatous polyps, the positivity of CD44, FVIII-RA, and p21ras was 75%, 62%, and 88%, respectively. In patients with colorectal carcinomas the positivity of CD44 was 55%, and for p21ras it was 52%. The median of FVIII-RA was 4 MVC (range, 0.0 to 32.33). MVC was greater than 4 in 53% of the patients with colorectal carcinomas. In univariate analysis, a significantly longer relapse-free time (CD44: P = .0004; FVIII-RA: P = .0006) and overall survival time (CD44: P = .0001; FVIII-RA: P = .001) were observed for patients with CD44-negative tumors and MVC below 4 as compared to those with CD44-positive tumors and MVC greater than 4. Similar observations were noted in patients with Dukes B and C disease and the rectum as the site of tumor. In multivariate analysis, only CD44 correlated significantly with both relapse-free (P = .0003) and overall survival (P = .00001).

CONCLUSION

Univariate analysis showed CD44 and MVC to be independent predictors of prognosis in colorectal carcinomas. Multivariate analysis showed that CD44 positivity was the most important indicator of an unfavorable prognosis for relapse-free and overall survival in patients with colorectal cancer. Thus, it can be deduced that whether CD44 is positive or negative in patients with colorectal cancer may have prognostic importance and in the future may be used as a factor in the pathologic evaluation of tumor specimens. This hypothesis needs to be tested prospectively in a larger number of patients.

Colon cancer during pregnancy. The gastroenterologist's perspective

Colon cancer during pregnancy is uncommon but not rare, with an estimated incidence of several hundred cases per year in the United States. This type of cancer tends to have a poor prognosis that is attributable to delays in diagnosis and advanced disease at diagnosis. The diagnosis frequently is delayed because symptoms of colon cancer, such as rectal bleeding, nausea and vomiting, and constipation, often are attributed to normal pregnancy or minor complications of pregnancy. Pregnancy affects the diagnostic evaluation and therapy of colon cancer because of fetal risks of diagnostic tests and therapy. Appropriate medical evaluation of significant lower gastrointestinal complaints during pregnancy can lead to an earlier and improved diagnosis.

Multiple synchronous primaries of the gastrointestinal tract: a molecular case report

Six synchronous gastrointestinal primaries were identified in a 70 year old male with no known cancer predisposition syndrome or recognized risk factors except alcohol abuse. These specimens appeared to be independent and unrelated by gross and histopathological examination. In order to further evaluate the six tumors, we analyzed selected DNA sequences for alterations in the K-ras oncogene and p53 tumor suppressor gene. In addition, three loci were analyzed to determine microsatellite instability. Using the polymerase chain reaction, single stranded conformational polymorphism, and DNA sequencing, we demonstrated that each primary manifests genetic characteristics typical of the tissue of origin. In addition, one primary, a moderately differentiated colon adenocarcinoma, exhibited mutations not detected in the other specimens. This study suggests that these synchronous primaries arose independently and progressed along different carcinogenic pathways.