Inclusion Criteria:  rectal adenocarcinoma, World Health Organization (WHO) performance status 0-1, assessed by the MDT to be able to undergo capecitabine and oxaliplatin (CAPOX) treatment, 3) extramural vein invasion by magnetic resonance imaging (mrEMVI+) and  4) assessed by the multi-disciplinary team (MDT) to require either radiotherapy (RT) or long chemoradiotherapy (CRT) by the current standards.  Exclusion Criteria:  deficient mismatch repair (MMR) status, non-dihydropyrimidine dehydrogenase (DPYD) genotype, a contraindication to capecitabine, oxaliplatin or RT, or failing in blood tests that describe the adequate circulatory, liver and kidney function for chemotherapy.