840 participants (men and women) with a biopsy verified adenocarcinoma of the rectum scheduled for an open abdominal procedure were enrolled at 18 Swedish Hospitals during 1998-2013.
In the initial protocol patients were randomly assigned (1:1:1) between three different RT courses; 5x5 Gy with surgery within 1 week (SRT), 5x5 Gy with surgery after 4-8 weeks (SRT-delay) or 25x2 Gy during 5 weeks without concomitant chemotherapy and surgery after 4-8weeks (LRT-delay). After a protocol amendment on May 21, 1999, participating hospitals could choose to randomise patients to just the short-course radiotherapy arms (1:1) or to all three arms.
Randomisation was done by telephone by the Regional Cancer Centre in Stockholm, Sweden, after assessing inclusion and exclusion criteria. Computer generated randomisation lists were constructed by use of permuted block technique (block size of six for the three- arm randomisation, block size of four for the two-arm randomisation) and stratified by participating center. Investigators and patients were not masked to treatment.
Follow-up was recommended at 3-, 6- and 12 months after surgery, and yearly thereafter. Although follow-up according to national guidelines with a minimum follow-up at 1 and 3 years was allowed. Patient data was also collected from the Swedish ColoRectal Cancer Register (SCRCR) and medical records.
Primary outcome:
- Time to local recurrence.
Secondary outcomes:
- Recurrence-free survival
- Frequency of postoperative complications
- Frequency of tumour regression