Tobin 1971

Methods	RCT with randomisation by card drawn by an individual not involved with the study. Allocation probably made in a concealed manner after randomisation. Patient, outcome assessors and treating team all aware of allocation after trial started. No indication of power calculation. Several different tumours studied: head and neck, uterine cervix, urinary bladder, rectal, brain and oesophagus
Participants	Group 1: 17 adults with carcinoma of the head and neck, 9 allocated to HBOT and 8 to control Group 2: 14 adults with carcinoma of the uterine cervix, 7 allocated to both HBOT and control Group 3. 6 adults with carcinoma of the urinary bladder, 3 allocated to each of HBOT and control Group 4. 4 adults with carcinoma of the rectum, 2 allocated to each of HBOT and control Group 5. 4 adults with glioblastoma of the brain, 2 allocated to each of HBOT and control Group 6. 4 adults with carcinoma of the oesophagus, 2 allocated to each of HBOT and control A further three patients allocated to HBOT were incomplete when trial ceased and have not been analysed
Interventions	Control: exact dose and fractionation schedules not given, but 'normal fractionation implies 24 to 30 fractions over six weeks approximately and varied with tumour site HBOT: same regimen, conducted at 3 ATA breathing 100% oxygen, total compression time about 50 minutes
Outcomes	Death at 1 and 2 years
Notes	Trial terminated after explosive decompression of the chamber due to degradation of chamber wall from radiation Schulz rating: randomisation: B; allocation concealment: A; selection bias: A; blinding: C
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Low risk	A ‐ Adequate