Short summary

We will investigate circulating tumor DNA in patients before and after surgery and during any chemotherapy for colon cancer. The purpose is to identify markers for relapse and for treatment effect. Two parallel cohorts are enrolled in Denmark and in Brazil and they serve as eachother's confirmators.

Rationale

Colorectal cancer is a serious malignant disease worldwide. In Brazil, there is a rapid increase in incidence and a modest increase in mortality. In Denmark, there is a modest increase in incidence and mortality is declining. The vast majority of the patients (85%) can be offered surgery with curative intent, but a considerable part of them will recur within two years with distant metastases, especially in the liver. Postoperative, adjuvant, chemotherapy reduces relapses and mortality, but there is a substantial over-treatment.

Circulating tumor specific DNA (ctDNA) as a "liquid biopsy" has recently gained considerable interest as a marker of potential clinical value. An Australian study analyzed tumor specific, mutated DNA in plasma from stage II patients. The results show that patients with mutated DNA in the circulation after the operation all died within two years, whereas patients without mutated DNA had a 3-year survival rate of 90%. The study was based on individual next generation sequencing (NGS) and subsequent polymerase chain reaction (PCR) analysis of the present mutations. This is a costly and laborious approach for daily clinical application and new, easier methods are warranted.

Aberrant methylation occurs in almost all malignant tumors, and tumor specific methylated DNA has been suggested for early diagnosis and screening, but it has not yet been generally accepted for this purpose. Several papers have shown that circulating methylated DNA holds prognostic information, but there are no large studies dealing with treatment monitoring or diagnosis and follow-up of minimal residual disease.

The neuropeptide Y-gene (NPY) encodes a peptide widely expressed in central nervous tissue with influence on many physiological functions. Preliminary results showed that tumor specific methylation of NPY occurs in 99% of colonic adenocarcinomas and polyps and in 50% of adjacent colon tissue, but not in normal colon mucosa. Tumor specific methylation is found in 90% of patients with metastatic colorectal cancer and in 50% of patients with localized disease.

The present protocol is conducted in collaboration between the centers in Brazil and Denmark. The main document describes the common parts and the appendices any specific or additional national procedures.

Description of the cohort

Adult patients with biopsy proven colon cancer and clinical stage determined on the preoperative MDT conference as T3-T4 or N+ and M0.

Data and biological material

Serial blood samples.

Collaborating researchers and departments

Department of Surgery, Esbjerg Hospital

• Head of Department Christina Tinghus

Department of Organ Surgery, Lillebaelt Hospital

• Head of Department Hans Rahr

Department of Oncology, Lillebaelt Hospital, 

• Lars Henrik Jensen
• Louise Raunkilde
• Torben Frøstrup Hansen

Department of Clinical Biochemistry, Lillebælt Hospital

• Rikke Fredslund Andersen, Molecular Biologist

Collaborators in Sao Paulo, Brazil.