Oligometastatic deposits of prostate cancer found within the sigmoid pericolic fat that was resected for colonic adenocarcinoma: a case report.

BACKGROUND Prostate cancer may rarely metastasize to the colon and colonic lymph nodes, and local treatment of oligometastatic deposits may improve oncological outcomes. Immunohistochemical stains are used to determine the most likely source of metastatic deposits when they are seen within surgical specimens. The aim of this case report is to illustrate how such techniques were used to identify unexpected prostatic metastases within the pericolic fat of a sigmoid colon resection specimen following elective curative surgery for colorectal cancer. To our knowledge, this is the first report of complete excision of oligometastatic deposits of prostate cancer found incidentally within the specimen of another cancer. CASE REPORT An 89-year-old Caucasian man underwent sigmoid colectomy for an obstructing colorectal cancer in the sigmoid colon with some mesenteric lymphadenopathy. He had previously received radical radiotherapy for prostate cancer 10 years earlier. When the specimen was examined by the histopathologist, it was noted that the pericolic fat adjacent to the colorectal adenocarcinoma contained some metastatic deposits. Positive immunohistochemical staining for prostate-specific antigen and prostate-specific acid phosphatase with negative staining for CDX2 and CK20 revealed these to be prostatic metastases rather than colonic. Since these were completely excised, and there were no other metastases, this represented a serendipitous, curative excision of oligometastatic deposits of an additional cancer to the one that was being treated. CONCLUSIONS This case illustrates how immunohistochemical staining may be used to distinguish the source of metastatic deposits based on the likelihood of primary tumor from a careful and thorough patient history

Tetraspanin 6 is a regulator of carcinogenesis in colorectal cancer.

Early stages of colorectal cancer (CRC) development are characterized by a complex rewiring of transcriptional networks resulting in changes in the expression of multiple genes. Here, we demonstrate that the deletion of a poorly studied tetraspanin protein Tspan6 in Apc mice, a well-established model for premalignant CRC, resulted in increased incidence of adenoma formation and tumor size. We demonstrate that the effect of Tspan6 deletion results in the activation of EGF-dependent signaling pathways through increased production of the transmembrane form of TGF-α (tmTGF-α) associated with extracellular vesicles. This pathway is modulated by an adaptor protein syntenin-1, which physically links Tspan6 and tmTGF-α. In support of this, the expression of Tspan6 is frequently decreased or lost in CRC, and this correlates with poor survival. Furthermore, the analysis of samples from the epidermal growth factor receptor (EGFR)-targeting clinical trial (COIN trial) has shown that the expression of Tspan6 in CRC correlated with better patient responses to EGFR-targeted therapy involving Cetuximab. Importantly, Tspan6-positive patients with tumors in the proximal colon (right-sided) and those with KRAS mutations had a better response to Cetuximab than the patients that expressed low Tspan6 levels. These results identify Tspan6 as a regulator of CRC development and a potential predictive marker for EGFR-targeted therapies in CRC beyond RAS pathway mutations

Role of endoscopic ultrasound-guided fine-needle aspiration in the diagnosis of solid pancreatic and peripancreatic lesions: is onsite cytopathology necessary?

AbstractObjectivesThe reported median diagnostic yield from endoscopic ultrasound (EUS) fine-needle aspiration (FNA) cytology is 78% (range 39–93%). The aim of this study is to describe a single-centre experience in the diagnostic work-up of solid pancreatic and peripancreatic masses without the benefit of an onsite cytopathologist.MethodsIn a consecutive series of 429 EUS examinations performed over a 12-month period by a single operator, 108 were on non-cystic pancreatic or biliary lesions. Data were collected prospectively and the accuracy of FNA was assessed retrospectively using either surgery or repeat imaging as the benchmark in the presence or absence of malignancy.ResultsOf the 108 FNAs, 102 (94%) were diagnostic, four were falsely negative (FN) and two were atypical and considered equivocal. There were 78 pancreatic lesions, of which 65 were true positives (TP), 11 true negatives (TN) and two FN, giving an overall accuracy of 97% (76/78). Of nine periampullary lesions, two were TP, six were TN and one was FN, giving an overall accuracy of 89% (8/9). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of EUS-FNA for pancreatic and periampullary lesions combined were 96%, 100%, 100% [95% confidence interval (CI) 95–100%], 85% (95% CI 62–97%) and 97%, respectively. There were 21 bile duct lesions, of which 10 were TP, eight TN, two atypical and one FN, giving an overall accuracy of 86% (18/21). The sensitivity, specificity, PPV, NPV and accuracy of EUS-FNA for biliary lesions were 91%, 100%, 100% (95% CI 69–100%), 91% (95% CI 59–100%) and 95%, respectively.ConclusionsThe diagnostic accuracy of EUS-FNA for pancreatic lesions in our series was 97% and the PPV for the three subgroups of lesion type was 100%; these figures are comparable with the best rates reported in the literature, despite the absence of onsite cytopathology. These rates are potentially a direct result of high-volume practice, dedicated endosonography and cytopathology. These results show that it is possible to achieve high rates of accuracy in places where logistical issues make it impossible to maintain a cytopathologist in the endoscopy suite. In addition, our results contribute to the limited, collective global experience on the effectiveness of EUS-FNA in periampullary and biliary lesions