Thymidylate synthase (TYMS) is an important enzyme for 5-fluorouracil (5-FU) metabolism in metastatic colorectal cancer (mCRC) patients. The search for this enzyme in circulating tumor cells (CTCs) can be a powerful tool to follow-up cancer patients. mCRC patients were enrolled before the beginning of 5-FU-based chemotherapy. The blood was filtered on Isolation by Size of Epithelial Tumor Cells (ISET), and the analysis of TYMS expression in CTCs was made by immunocytochemistry. Additionally, we verified TYMS staining in primary tumors and metastases from the same patients. There were included 54 mCRC patients and 47 of them received 5-FU-based chemotherapy. The median CTCs number was 2 per mL. We were not able to analyze immunocytochemistry in 13 samples (9 patients with absence of CTCs and 4 samples due to technical reasons). Therefore, TYMS expression on CTCs was analyzed in 34 samples and was found positive in 9 (26.5%). Six of these patients had tumor progression after treatment with 5-FU. We found an association between CTC TYMS staining and disease progression (DP), although without statistical significance (P 5 0.07). TYMS staining in primary tumors and metastases tissues did not have any correlation with disease progression (P 5 0.67 and P 5 0.42 respectively). Patients who had CTC count above the median (2 CTCs/mL) showed more TYMS expression (P 5 0.02) correlating with worse prognosis. Our results searching for TYMS staining in CTCs, primary tumors and metastases suggest that the analysis of TYMS can be useful tool as a 5-FU resistance predictor biomarker if analyzed in CTCs from mCRC patients.Colorectal cancer (CRC) was the third most commonly diagnosed cancer in both men and women in the last 3 years in the United States. 1-3 For metastatic patients, the strategy for treatment is mostly 5-Fluorouracil-based chemotherapy, which shows high efficacy in a subset of patients. However, even those patients can experience disease progression due to 5-FU resistance. 4 TYMS is a constitutive enzyme that catalyzes the reductive methylation of deoxyuridine monophosphate (dUMP) by CH 2 H 4 folate to produce deoxythymidine monophosphate (dTMP) and H 2 folate leading to DNA replication and repair. 5 An upgrade of resistance to the treatment has been often correlated to increased levels of TYMS in cancer cells. 6 Others have demonstrated that intratumoral TYMS mRNA expression levels (in paraffin-embedded tissues) are independent predictive markers of survival for 5-FU and oxaliplatin combination therapy. 7 Although the presence of high levels of TYMS presents poor outcome, it becomes hard to evaluate since there are heterogeneity among the population, methods and techniques as well. Furthermore, the best way to detect the presence of TYMS and its real value remains unclear 8 as there is not a consensus about the role of TYMS expression in mCRC published in the last 20 years. Thence, analyzing

Background: Quantification of Circulating Tumor Cells (CTCs) as a prognostic marker in metastatic colorectal cancer (mCRC) has already been validated and approved for routine use. However, more than quantification, qualification or characterization of CTCs is gaining importance, since the genetic characterization of CTCs may reflect, in a real time fashion, genetic profile of the disease. Objective: To characterize KRAS mutations (codon 12 and 13) in CTCs from patients with mCRC and to compare with matched primary tumor. Additionally, correlate these mutations with clinical and pathological features of patients. Methods: Blood samples were collected from 26 patients with mCRC from the AC Camargo Cancer Center (São Paulo-Brazil). CTCs were isolated by ISET technology (Isolation by Size of Epithelial Tumors; Rarecells Diagnostics, France) and mutations analyzes were performed by pyrosequencing (QIAGEN). Results: KRAS mutation was detected in 7 of the 21 cases (33%) of samples from CTCs. In matched primary tumors, 9 of the 24 cases (37.5%) were found KRAS mutated. We observed that 5 of the 9 samples with KRAS mutation in their primary tumor had also KRAS mutation in CTCs, meaning a concordance of 71% of matched cases (P D 0.017). KRAS mutation neither on primary tumor nor in CTCs was associated with clinical-pathological parameters analyzed. Conclusion: Faced with a polyclonal disease like colorectal cancer, which is often treated with alternating and successive lines of chemotherapy, real time genetic characterization of CTCs, in a fast and feasible fashion, can provide important information to clinical management of metastatic patients. Although our cohort was limited, it was possible to show a high grade of concordance between primary tumor and CTCs, which suggests that CTCs can be used as surrogate of primary tumors in clinical practice, when the knowledge of mutation profile is necessary and the primary tumor is not available.

No abstract

Assessment of the accuracy of diagnostic procedures is made independent of diagnostic criteria by means of a receiver-operating-characteristics (ROC) curve. We performed ROC analysis for the major serum antiproteases: alpha-1-antitrypsin (A1AT) and alpha-2-macroglobulin (A2M), in 99 cancer patients compared with 71 normal individuals. A1AT and A2M were significantly higher in cancer patients (p less than 0.0005). By comparing true positive and false positive rates for different serum levels, ROC analysis showed that serum A1AT quantification seems more useful in clinical practice than serum A2M.

No abstract