The purpose of this study is the investigation of new host-microbiome interactions promoting adenoma formation and adenocarcinoma progression. For that purpose, the investigators will collect saliva, stool and colon biopsy specimens from patients referred to colonoscopy or surgical resection of colorectal tumor. Besides, a questionnaire about diet, lifestyle and medical history will be collected. Sample analysis will involve simultaneous characterization of host and microbiota genomic and transcriptomic components.

Lower GI endoscopy patients

Inclusion Criteria:

• Participant is willing and able to give informed consent for the participation in the study before any protocol-specific screening procedures are performed

• Male or female, aged 18 years or above

• Referred to lower GI endoscopy. Referral reasons can be among others:

  • Positive FOBT (Fecal Occult Blood Test)
  • Follow up after polypectomy
  • Screening because of age
  • Bleeding
  • Abdominal pain
  • Familial or past history of colon cancer or adenoma
  • Abnormal imaging such as barium enema
  • Change in bowel habits

• Both self-referrals, referrals from external GP or specialists and internal referrals can be included.

Exclusion Criteria:

• Previous diagnosis of an inflammatory bowel disease
• Previous diagnosis of intestinal polyposis syndrome

CRC patients

Inclusion criteria:

• Participant is willing and able to give informed consent for the participation in the study before any protocol-specific screening procedures are performed
• Male or female, aged 18 years or above
• Diagnosis of CRC for which resection is planned
• Both internal and external referrals from specialists can be included

Exclusion Criteria:

• Previous diagnosis of an inflammatory bowel disease
• Previous diagnosis of intestinal polyposis syndrome

Study participants are patients with CRC that will undergo surgical tumor resection or patients referred for lower GI endoscopy.