Association Between Baseline Circulating Tumor Cells, Molecular Tumor Profiling, and Clinical Characteristics in a Large Cohort of Chemo-naïve Metastatic Colorectal Cancer Patients Prospectively Collected.

BACKGROUND: Clinicopathologic characteristics and prognostic and predictive factors offer valuable guidance when selecting optimal first-line treatment in patients with metastatic colorectal cancer (CRC). The association between baseline circulating tumor cell (bCTC) count, molecular tumor profile, and clinicopathologic features was analyzed in a chemo-naïve metastatic CRC population. PATIENTS AND METHODS: A total of 1202 patients from the Spanish VISNÚ-1 (FOLFIRINOX/bevacizumab vs. FOLFOX/bevacizumab) and VISNÚ-2 (FOLFIRI/bevacizumab vs. FOLFIRI/cetuximab; RAS-wildtype) studies were analyzed for mutational status and bCTC count. The association between clinicopathologic characteristics and bCTC count, mutational status, and microsatellite instability (MSI) was analyzed in 589 eligible patients. RESULTS: Interestingly, 41% of the population studied presented ≥3 bCTC count. bCTC count ≥3 was associated with worse performance status (according Eastern Cooperative Oncology Group scale), stage IV at diagnosis, at least 3 metastatic sites, and elevated carcinoembryonic antigen (CEA) levels; but not with RAS or BRAF mutations or high MSI. BRAFmut (BRAF mutated) tumors were associated with right-sided primary tumors, peritoneum, distant lymph node metastasis, and less frequent liver involvement. RASmut (RAS mutated) was associated with worse performance status; stage IV at diagnosis; right-sided primary tumors; liver, lung, and bone metastases; at least 3 metastatic sites; and elevated CEA, whereas PIK3CAmut (PIK3CA mutated) tumors were associated with right-sided primary tumors, high CEA serum levels, and older age. High MSI was associated with right-sided primary tumors, distant lymph nodes metastasis, and lower CEA levels. CONCLUSIONS: In our study, elevated bCTCs and RASmut were associated with clinicopathologic features known to be associated with poor prognosis; whereas the poor prognosis of BRAFmut tumors in chemo-naïve metastatic CRC is not explained by associations with poor clinicopathologic prognostic factors, except right-sided primary tumors. TRIAL REGISTRATION NUMBER: VISNU 1 ClinicalTrials.gov ID: NCT01640405/ VISNU 2 ClinicalTrials.gov ID: NCT01640444.

Metilación de p16 en pacientes intervenidos de cáncer colorrectal tras un largo periodo de seguimiento / p16 gene methylation in colorectal cancer patients with long-term follow-up

Introducción: el gen p16 está implicado en la regulación del ciclo celular y se considera un importante gen supresor de tumores. Objetivos: se han descrito diferentes mecanismos de inactivación génica, en este estudio nos hemos centrado en la metilación del promotor del gen p16. En el cáncer colorrectal la metilación de p16 es una alteración frecuente. Material y métodos: se incluyeron 326 pacientes con cáncer colorrectal esporádico. El ADN se extrajo de muestras tumorales obtenidas durante la cirugía. La metilación del promotor se analizó mediante un proceso de modificación con bisulfito y posterior PCR cuantitativa especifica para metilación. Se analizó la frecuencia de la metilación de p16 y se comparó con las variables clinicopatológicas. Resultados: la metilación del gen p16 se detectó en el 24,8% de los pacientes. La metilación de p16 se relacionó con el grado de diferenciación y con la localización tumoral: la metilación fue mas frecuente en los tumores pobremente diferenciados y tuvo una baja frecuencia en el colon distal. La metilación del promotor de p16 discrimina un subgrupo de pacientes con mejor pronóstico en los tumores pobremente diferenciados. Conclusiones: la metilación de p16 es un evento frecuente en nuestra población y es capaz de inducir diferencias en la supervivencia global de los pacientes con tumores moderadamente diferenciados(AU)

Introduction: p16 gene plays an important role in the cell cycle regulation and is considered an important tumor suppressor gene. Several mechanisms of gene inactivation have been described; in this study we have focused on p16 gene promoter methylation. In colorectal cancer p16 gene methylation is a frequent event. Methods: 326 patients with sporadic colorectal cancer were included. DNA was extracted from tumor tissue samples obtained during the surgical procedure. Promoter methylation was analyzed using bisulfite modification and was detected by quantitative methylation- specific PCR. Frequency of p16 methylation was analyzed and compared with other clinicopathological variables. Results: p16 gene methylation was detected in 24,8% of patients. Methylation was associated with differentiation grade and with tumor location: methylation was frequent in poorly differentiated tumors and had low frequency in distal colon. The p16 promoter methylation discriminated a subgroup of patients with better prognosis in poorly differentiated tumors. Conclusions: p16 methylation was a frequent event in our population and was able to induce differences in the overall survival of patients with poorly differentiated tumors(AU)