ABCSG R07 Rectal Cancer Registry

In Austria, patients with rectal cancer that has not spread to other parts of the body are typically treated with either total neoadjuvant therapy (TNT) or immunotherapy, depending on their microsatellite status (DNA repair capacity). However, treatment can vary considerably between hospitals in Austria. These differences may include the type and duration of treatment, as well as the active ingredients used. There are currently no clear recommendations on which exact treatment is best for each specific case. The aim of this observational study is to collect information on the different treatments used in Austria for patients with localized rectal cancer and to document the outcomes of these treatments. Only information and samples collected as part of the patients' routine care will be used for the study. Participation in the study will not change or affect the treatment chosen by the treating physician.

Inclusion Criteria: * Female and male participants with age \>= 18 years * Signed informed consent obtained prior to registration of the participant. * Localized rectal cancer treated with TNT or localized, non-metastatic dMMR/MSI-H rectal cancer, irrespective of treatment Exclusion Criteria: * Distant metastases at primary diagnosis