UNIT OF MEASUREMENT: Cumulative incidence of patients with locoregionally recurrent colon cancer in curatively treated primary colon cancer patients; MEASUREMENT TOOL: Registration of diagnosis of locoregionally recurrent colon cancer in the electronic patient file.

The competing-risk cumulative incidence will be calculated, which will inform on the proportion of patients who have developed locoregionally recurrent colon cancer at that time point.

UNIT OF MEASUREMENT: Risk factors for development of locoregionally recurrent colon cancer in primary colon cancer patients; MEASUREMENT TOOL: Registration of clinical and pathological covariates of primary colon cancer in the electronic patient file and national pathological database (PALGA).

Clinical and pathological risk factors for the development of locoregionally recurrent colon cancer will be identified using multivariable competing-risk risk regression analyses, according to the cause-specific hazard approach. This will inform on specific clinical and pathological covariates which increase or decrease the risk for development of locoregionally recurrent colon cancer.

UNIT OF MEASUREMENT: Proportions of treatment given to patients with locoregionally recurrent colon cancer; MEASUREMENT TOOL: Registration of treatment for locoregionally recurrent colon cancer in the electronic patient file.

Using descriptive statistics, treatment patterns of patients with locoregionally recurrent colon cancer will be identified. Groups that will be created, will also be used to assess overall survival.

UNIT OF MEASUREMENT: Overall survival of patients with locoregionally recurrent colon cancer; MEASUREMENT TOOL: Registration of vital status in the national personal records database.

Overall survival will be estimated for patients with locoregionally recurrent colon cancer, stratifying for different groups (i.e. treatment, diagnosis of synchronous metastases, diagnosis within first year after primary resection, etc.)