Prospective multicenter registry study to assess the frequency of Lynch syndrome among patients with colorectal cancer in Russia

Blood and tumor samples will be obtained from enrolled patients. 4 ml of venous blood samples will be taken into a tube with EDTA and stored at -20 0C. Tumor samples will be taken during endoscopy or surgical treatment, embedded in paraffin and stored at room temperature.

Microsatellite instability in the tumor tissue will be determined by any method available in the participating center (immunohistochemical or molecular genetic study). In case of detection of microsatellite instability/deficiency in the repair system of unpaired bases blood samples will be analyzed for the fact that germinal mutations in the DNA mismatch repair genes.

Patients will be followed up for 5 years after enrollment. During follow up correlation of spectrum of germinal mutations with clinical data, effectiveness of therapy with immune checkpoint inhibitors, the spectrum of malignant neoplasms in the families of patients with Lynch syndrome, the impact of the presence of microsatellite instability/deficiency in the DNA mismatch repair genes on treatment tactics in the Russian Federation will be assessed.

Inclusion Criteria:

• Provision of written informed consent;
• Patients with histologically verified colon adenocarcinoma or patients with histologically verified synchronous neoplasms who have not previously received treatment for a second tumor;
• Age ≥ 18 years;
• Absence of antitumor treatment for a real tumor (it is allowed to include patients who have a history of antitumor treatment for other malignant tumors, if the period after treatment is more than 12 months).
• The ability of the patient, according to the Researcher, to fulfill the requirements of the Protocol;

Exclusion Criteria:

- Patients receiving chemotherapy or radiotherapy for colon cancer at the time of screening

Patients with colon adenocarcinoma who have not previously received antitumor treatment (chemo/radiation therapy) for a currently detected tumor

Before the start of the study, at the initiating visit, the monitor, together with the researchers and their staff, will review the protocol and the CRF. During the study, the monitor will regularly communicate remotely with the research center and check the process of inclusion of patients, the completeness of maintaining medical records of patients, the correctness of filling out the CRF. The researcher must provide the monitor with access to the relevant hospital documentation and other medical records to verify their compliance with the data recorded in the IRC. The data identifying the patient's identity will remain confidential.

6 months after completion of the study

upon the request