Background
High-grade neuroendocrine carcinomas (HGNECs) of the colon and rectum are rare, constituting less than 1 % of colorectal cancers. The purpose of this study was to identify the natural ...history and oncologic outcomes of this disease, describe the use of surgery, and determine the clinical and pathological factors associated with outcomes.
Methods
Following Institutional Review Board approval, patients with HGNEC were identified from our institutional database. Patient charts and pathology reports were analyzed retrospectively for clinical and pathological factors.
Results
A total of 126 patients with a median follow-up of 9 months were identified. Median survival was 13.2 months, and 85 (67 %) patients had metastatic disease at diagnosis. Three-year overall survival (OS) was 5 and 18 % for patients with and without metastatic disease, respectively. Factors associated with improved OS on multivariable analysis were absence of metastatic disease and presence of an adenocarcinoma component within the tumor. In patients with metastatic disease, response to chemotherapy was the only factor associated with survival. In patients with localized disease, an adenocarcinoma component within the tumor was the only factor associated with survival. Resection of tumor was not associated with survival in either localized or metastatic disease.
Conclusion
High-grade colorectal NECs are extremely aggressive tumors with poor prognosis. Patients appear to have a marginally better prognosis if they present without metastatic disease, have an adenocarcinoma component within their tumor, or respond to chemotherapy. Surgery, particularly in the presence of metastatic disease, may not offer a survival benefit for the majority of patients.
Immune checkpoint blockade targeting the programmed death-1 (PD-1) pathway has shown efficacy in several types of cancers including mismatch-repair-deficient colorectal carcinoma. In some tumor ...types, programmed death-ligand 1 (PD-L1) expression detected by immunohistochemistry has shown utility as a predictive marker for response to anti-PD-1 therapies. This utility, however, remains to be determined in colorectal carcinoma. In addition, although tumor-infiltrating lymphocytes have been associated with better prognosis in colorectal carcinoma, the prognostic value of PD-1 expression in these lymphocytes and its interaction with PD-L1 expression still await investigation. To address these questions, we performed a pilot study to evaluate the patterns of PD-L1 and PD-1 immunohistochemical expression on colorectal carcinoma cells and their tumor-infiltrating lymphocytes, respectively. Using tissue microarray, we found that 5% (19/394) of colorectal carcinomas exhibited high tumor PD-L1 expression, and 19% (76/392) had elevated numbers of PD-1-positive tumor-infiltrating lymphocytes. PD-L1 levels correlated with PD-1 levels (P<0.001), and mismatch-repair-deficient tumors had significantly higher rates of high PD-L1 and PD-1 expression when compared with mismatch-repair-proficient tumors (18% vs 2% and 50% vs 13%, respectively; P<0.001 for both). Staining intensity was also stronger for both markers in mismatch-repair-deficient tumors. Furthermore, we observed that among patients with mismatch-repair-deficient colorectal carcinoma, PD-1/PD-L1 expression stratified recurrence-free survival in an inter-dependent manner: an association between high PD-1-positive tumor-infiltrating lymphocytes and improved recurrence-free survival (P=0.041) was maintained only when the tumors had low-level PD-L1 expression (P=0.006); patients whose tumors had both high PD-1-positive tumor-infiltrating lymphocytes and high PD-L1 expression had a significantly worse recurrence-free survival (P<0.001). Thus, our results not only provide a foundation for further assessment of PD-L1 immunohistochemistry as a predictive marker for anti-PD-1 therapy in colorectal carcinoma, they also shed light on the prognostic impact of tumor-infiltrating lymphocytes in different subsets of mismatch-repair-deficient colorectal carcinomas.
The utility of immunohistochemical detection of DNA mismatch repair (MMR) protein in screening colorectal tumors for hereditary nonpolyposis colorectal cancer (HNPCC) syndrome has been the focus of ...much intensive research over the last 10 years. Particular attention has been given to the relative usefulness of immunohistochemistry (IHC) versus testing of tumor microsatellite instability (MSI). Earlier work that focused on mutL homolog 1 (MLH1) and mutS homolog 2 (MSH2) has created a false impression that IHC has a lower sensitivity than MSI testing in predicting germline mutation. More recent studies that included postmeiotic segregation increased 2 (PMS2) and MSH6, on the other hand, have demonstrated an IHC predictive value that is virtually equivalent to that of MSI testing. Such added value of PMS2 and MSH6 can be explained by the biological and biochemical properties of the MMR proteins. On the premise that IHC with PMS2 and MSH6 is as sensitive as MSI testing, given that IHC is easily available and generally inexpensive and, importantly, identifies the affected gene, it is reasonable to regard IHC as a more optimal first-line screening tool than MSI testing for identifying HNPCC. MSI testing can provide a fallback position in equivocal situations, while remaining an important research tool. However, for IHC to be used as a first-line screening test requires that both pathologists and clinicians be aware that IHC results may be construed as "genetic information," and that appropriate procedures should be established to ensure patient understanding and consent.
To compare the mutational and copy number profiles of primary and metastatic colorectal carcinomas (CRCs) using both unpaired and paired samples derived from primary and metastatic disease sites.
We ...performed a multiplatform genomic analysis of 736 fresh frozen CRC tumors from 613 patients. The cohort included 84 patients in whom tumor tissue from both primary and metastatic sites was available and 31 patients with pairs of metastases. Tumors were analyzed for mutations in the KRAS, NRAS, BRAF, PIK3CA, and TP53 genes, with discordant results between paired samples further investigated by analyzing formalin-fixed, paraffin-embedded tissue and/or by 454 sequencing. Copy number aberrations in primary tumors and matched metastases were analyzed by comparative genomic hybridization (CGH).
TP53 mutations were more frequent in metastatic versus primary tumors (53.1% v 30.3%, respectively; P < .001), whereas BRAF mutations were significantly less frequent (1.9% v 7.7%, respectively; P = .01). The mutational status of the matched pairs was highly concordant (> 90% concordance for all five genes). Clonality analysis of array CGH data suggested that multiple CRC primary tumors or treatment-associated effects were likely etiologies for mutational and/or copy number profile differences between primary tumors and metastases.
For determining RAS, BRAF, and PIK3CA mutational status, genotyping of the primary CRC is sufficient for most patients. Biopsy of a metastatic site should be considered in patients with a history of multiple primary carcinomas and in the case of TP53 for patients who have undergone interval treatment with radiation or cytotoxic chemotherapies.
Colorectal cancer is the second leading cause of cancer death in the United States, with over 50,000 deaths estimated in 2014. Molecular profiling for somatic mutations that predict absence of ...response to anti-EGFR therapy has become standard practice in the treatment of metastatic colorectal cancer; however, the quantity and type of tissue available for testing is frequently limited. Further, the degree to which the primary tumor is a faithful representation of metastatic disease has been questioned. As next-generation sequencing technology becomes more widely available for clinical use and additional molecularly targeted agents are considered as treatment options in colorectal cancer, it is important to characterize the extent of tumor heterogeneity between primary and metastatic tumors.
We performed deep coverage, targeted next-generation sequencing of 230 key cancer-associated genes for 69 matched primary and metastatic tumors and normal tissue. Mutation profiles were 100% concordant for KRAS, NRAS, and BRAF, and were highly concordant for recurrent alterations in colorectal cancer. Additionally, whole genome sequencing of four patient trios did not reveal any additional site-specific targetable alterations.
Colorectal cancer primary tumors and metastases exhibit high genomic concordance. As current clinical practices in colorectal cancer revolve around KRAS, NRAS, and BRAF mutation status, diagnostic sequencing of either primary or metastatic tissue as available is acceptable for most patients. Additionally, consistency between targeted sequencing and whole genome sequencing results suggests that targeted sequencing may be a suitable strategy for clinical diagnostic applications.
Proteins overexpressed in early-stage cancers may serve as early diagnosis and prognosis markers as well as targets for cancer therapies. In this study, we examined the expression of an essential ...amino acid carrier SLC7A5 (LAT1, CD98, or 4F2 light chain) in cancer tissue from two well-annotated cohorts of 575 cases of early-stage and 106 cases of late-stage colorectal cancer patients. Immunohistochemistry showed SLC7A5 overexpression in 72.0% of early-stage and 56.6% of late-stage cases. SLC7A5 expression was not influenced by patient gender, age, location, or mismatch repair status, although it appeared to be slightly less prevalent in tumors of mucinous differentiation or with lymphovascular invasion. Statistical analyses revealed a positive correlation between SLC7A5 overexpression and both overall survival and disease-free survival in early-stage but not late-stage cancers. Co-expression analyses of the TCGA and CPTAC colorectal cancer cohorts identified a network of gene transcripts positively related to SLC7A5, with its heterodimer partner SLC3A2 having the highest co-expression score. Network analysis uncovered the SLC7A network to be significantly associated with ncRNA such as tRNA processing and the mitotic cell cycle. Since SLC7A5 is also a marker of activated lymphocytes such as NK, T, and B lymphocytes, SLC7A5 overexpression in early colorectal cancers might trigger a strong anti-tumor immune response which could results in better clinical outcome. Overall, our study provides clear evidence of differential SLC7A5 expression and its prognostic value for early-stage colorectal cancer, although the understanding of its functions in colorectal tumorigenesis and cancer immunity is currently rather limited and awaits further characterization.
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