The prognostic efficacy of cell-free DNA hypermethylation in colorectal cancer

// Simon Ladefoged Rasmussen 1, 2, 3 , Henrik Bygum Krarup 2, 4 , Kare Gotschalck Sunesen 1 , Martin Berg Johansen 5 , Mogens Tornby Stender 1 , Inge Sokilde Pedersen 2, 4 , Poul Henning Madsen 2, 4 and Ole Thorlacius-Ussing 1, 2, 3 1 Department of Gastrointestinal Surgery, Aalborg University Hospital, Aalborg, Denmark 2 Clinical Cancer Research Center, Aalborg University Hospital, Aalborg, Denmark 3 Department of Clinical Medicine, Aalborg University, Aalborg, Denmark 4 Section of Molecular Diagnostics, Clinical Biochemistry, Aalborg University Hospital, Aalborg, Denmark 5 Unit of Clinical Biostatistics, Aalborg University Hospital, Aalborg, Denmark Correspondence to: Simon Ladefoged Rasmussen, email: simon.rasmussen@rn.dk Keywords: colorectal cancer; DNA hypermethylation; prognosis; staging Received: September 08, 2017      Accepted: January 03, 2018      Published: January 09, 2018 ABSTRACT Epigenetic alterations in colorectal cancer (CRC) cause important differences in the underlying tumor biology and aggressiveness. DNA hypermethylation is central for the development of CRC but the prognostic impact remains elusive. We aimed to assess the association between cell-free hypermethylated DNA and stage and survival in colorectal cancer (CRC). We analyzed pre-treatment plasma samples from 193 patients with CRC. Thirty gene-promoter regions were analyzed using methylation specific PCR. We compared the median number (range) of hypermethylated promoter regions with CRC stage, and constructed a multivariable Cox-regression model adjusted for stage, to evaluate the added prognostic information. The median number of hypermethylated promoter regions was nine (0-28) in patients with distant metastasis compared to five (0-19) in patients without metastatic disease (p < 0.0001). The majority of the hypermethylated promoter regions inferred a poor prognosis. Cox-regression analysis adjusted for patient age, sex, pre-treatment CEA-levels, and disease stage, showed that RARB (HR = 1.99, 95% CI [1.07, 3.72]) and RASSF1A (HR = 3.35, 95% CI [1.76, 6.38]) hypermethylation inferred a significant effect on survival. The risk of metastasis increase with the number of cell-free hypermethylated promoter regions. The presence of RARB and RASSF1A hypermethylation indicated aggressive disease, regardless of stage at the time of diagnosis.