The primary objective is to validate that the Immunoscore® test (IS0 to IS4) is able to identify patients with high risk (IS 0-1) of relapse or death whichever occurs first among Stage III patients under oxaliplatin-based adjuvant therapy.

Then the prognostic value of Immunoscore® Colon to predict disease free survival (DFS) will be assessed in Stage III patients under Oxaliplatin treatment in each arm of the IDEA trial (6- months and 3-months treatment).

Finally, the additive value of the Immunoscore® test to stratify the DFS will be evaluated among standard clinical and biological parameters and tumor features.

Adult patients of both genders who have underwent surgical resection of stage III colon carcinoma and randomised to receive a 6-month or 3-month adjuvant therapy with modified FOLFOX 6 or CAPOX in the IDEA France trial.

Inclusion Criteria:

• Patient and tumor characteristics; 3-year clinical Follow-Up
• Data regarding other markers (eg. MSI)
• FFPE blocks available, including core tumor + invasive margin regions

Exclusion Criteria:

• Bouin fixative

Sample type:

• adjacent FFPE slices (4 μm each) per case (although only one slide is required for CD3 and one for CD8, with center of tumor (CT) and the invasive margin(IM) cut from FFPE blocks no more than 4 months before the Immunoscore® testing

Adult patient of both genders who have underwent surgical resection of stage III colon carcinoma