The clinical presentation of CI is very heterogeneous, perhaps explaining why clinical suspicion of this disease is so low. The presence of IRCI, and occurrence of peritoneal signs or onset of CI as severe abdominal pain without bleeding, should alert the physician to a potentially unfavorable course.

Colorectal cancer (CRC) is a major health problem in elderly people because of its high incidence and high mortality rate. Despite early screening programs, more than half of CRC patients are diagnosed at advanced stages. Fibroblast activation protein-α (FAP) expression in cancer-associated fibroblasts (CAFs) has been associated with a higher risk of metastases and poor survival. Here, we have analyzed the immunohistochemical expression of FAP in 41 adenoma-carcinoma sequences. In addition, FAP expression was analyzed individually and in combination with β-catenin (BCAT), CD44 and Cyclin-D1 expression in primary tumors and in their corresponding lymph node and liver metastases (n=294). Finally, soluble FAP (sFAP) levels in plasma from CRC patients (n=127) were also analyzed by ELISA. FAP was expressed only in CRC tissue and its expression level was found to be higher in tumors exhibiting deeper local invasion and poorer cancer cell differentiation. FAP and concomitant nuclear BCAT expression in cancer cells at the infiltrating front of primary tumors and in lymph node metastases was independently associated with 5- and 10-year cancer specific and disease-free survival. Moreover, lower sFAP levels correlated with poorer survival. These findings support the potential importance of FAP as a biomarker of CRC development and progression.

Background and Objective: Prolyl endopeptidase (PEP) (EC 3.4.21.26) is a serine peptidase involved in differentiation, development and proliferation processes of several tissues. Recent studies have demonstrated the increased expression and activity of this cytosolic enzyme in colorectal cancer (CRC). However, there are no available data about the impact of this peptidase in the biological aggressiveness of this tumor in patient survival.Methods: The activity of PEP in tissue (n=80) and plasma (n=40) of patients with CRC was prospectively analyzed by fluorimetric methods. Results were correlated with the most important classic pathological data related to aggressiveness, with 5-year survival rates and other clinical variables.Results: 1) PEP is more active in early phases of CRC; 2) Lower levels of the enzyme in tumors were located in the rectum and this decrease could be related with preoperative chemo-radiotherapy; 3) PEP activity in tissue was higher in patients with better overall and disease-free survival (log-rank p<0.01, Cox analysis p<0.01); 4) Plasmatic PEP activity was significantly higher in CRC patients than in healthy individuals and this was associated with distant metastases and with worse overall and disease-free survivals (log-rank p<0.05, Cox analysis p<0.05).Conclusions: PEP activity in tissue and plasma from CRC patients is an independent prognostic factor in survival. The determination of PEP activity in the plasma may be a safe, minimally invasive and inexpensive way to define the aggressiveness of CRC in daily practice.

Aminopeptidase N activity in tissue and plasma from CRC patients is an independent prognostic factor of 5-year survival. The determination of APN activity levels in the plasma may be a safe, minimally invasive, and inexpensive way to define the aggressiveness of CRC in daily practice.