AlfaOmega has been designed to streamline the study of the co-evolutionary landscape between tumor and host cells in a cohort of CRC patients, with the aim of understanding how their outcomes can be significantly improved (e.g. reduction of their chance of recurrence and survival improval). This clinical resource for integrative clinical data and sample collection will allow the molecular story-telling of CRC metastatic spread along time and space and the selection of appropriate patients for experimentally-driven trials.

AlfaOmega is an observational study that will follow a stage-mixed cohort of at least 500 patients through their course of treatments, until death or a minimum of 5 years. Patients will be longitudinally sampled and matched clinical data (including imaging) will be collected. Via a multi-tiered informed consensus process, AlphaOmega will also allow to develop companion diagnostics for molecular enrichment strategies in AIRC-driven proof-of-concept trials. To achieve the required level of 'experimental precision', patients will enter AlphaOmega at two different 'therapeutic checkpoints': i) prior to a surgical event or ii) prior to a systemic treatment. In the latter case patients with no previous lines of therapy for metastatic disease will be privileged.

To optimize the enrollment of patients, the longitudinal collection of data/samples and their logistic management, AlphaOmega has been designed as a flexible infrastructure organized in TIERS for the stepwise comprehension of the biological processes that drive tumor evolution, and precisely:

• TIER1, Monitoring: the ability to follow CRC evolution under standard of care treatments and to define new evolution-linked biomarkers. This will be achieved through the collection of clinical data, imaging data, FFPE tissue and frozen plasma/PBMC.
• TIER2, Modelling: the ability to develop pertinent experimental models to study evolutionary mechanisms and define evolution-targeting therapeutic strategies. This will be achieved through the collection of Fresh Tissue, Whole Blood, Stools, Buccal Swabs and other fluids.
• TIER3, Linking: the ability to access data and samples of patients enrolled in proof-of-concept trials to prove the efficacy and study/understand resistance mechanisms of evolution-targeting therapies. This will be achieved by introducing the connection in the trial protocol.

Inclusion Criteria:

1. TIER1 written Informed consent.
2. Patients ≥18 years of age.
3. Previous diagnosis of colorectal cancer, or a strong suspicion of CRC based on clinical and radiological findings.
4. In patients with previous diagnosis of CRC availability of diagnostic Formalin-Fixed, Paraffin Embedded (FFPE) blocks (surgical resection and/or tumor biopsies), or at least 10 slides (preferably 20). FFPE tissue blocks are always preferred to slides.
5. ECOG Performance status < 2.

Exclusion Criteria:

1. Any other current malignancy or malignancy diagnosed or relapsed within the past 5 years (other than non-melanomatous skin cancer, stage 0 melanoma in situ, and in situ cervical cancer)
2. Patient unable to comply with the study protocol owing to psychological, social or geographical reasons.
3. Known Human Immunodeficiency Virus (HIV), Hepatitis B Virus (HBV), Hepatitis C Virus (HCV) or syphilis infection.

Colorectal cancer patients