McIllmurray 1987.

Methods	RCT, parallel, 2 arms (GLA vs "inert placebo"), 40 months Summary risk of bias: moderate to high
Participants	People within 1 month following operation to remove Dukes's C colorectal cancer N: intervention 25 (plus some dropouts), control: 24 (plus some dropouts (analysed intervention 25, control 24). 5 dropped out, but arms unclear Level of risk for CVD: low Male: not reported Mean age (SD) years: intervention 62.1 (not reported), control 64.8 (not reported) Age range: intervention 48‐81, control 45‐77 Smokers: not reported Hypertension: not reported Medications taken by ≥ 50% of those in the control group: not reported Medications taken by 20%‐49% of those in the control group: not reported Medications taken by some, but < 20% of the control group: not reported Location: UK Ethnicity: not reported
Interventions	Type: supplement (Efamol) Comparison: GLA vs "inert placebo" (unclear what) Intervention: 6 capsules/d containing 500 mg GLA plus 10 mg natural vitamin E (Efamol). GLA 0.5 g/d, 60 mg/d vitamin E. Plus vitamin supplements including vitamin C, zinc sulphate and pyridoxine. Control: 6 capsules/d containing an inert placebo, identical in appearance (not specified what). Plus vitamin supplements including vitamin C, zinc sulphate and pyridoxine. Dose aim: (assuming placebo contains no PUFA) increase 0.5 g/d GLA, 5 kcal or 0.2% E GLA, assume 70% LA*, 4.2 g/d or 37.8 kcal/d or 1.9% E LA, 2.1% E n6 Baseline PUFA: unclear Compliance by biomarkers: unclear, no serum TC or tissue fatty acid levels reported. Compliance by dietary intake: unclear, states that one participant stopped taking the supplements at 12 months Energy intake: not reported Total fat intake: not reported SFA intake: not reported PUFA intake: not reported PUFA n‐3 intake: not reported PUFA n‐6 intake: not reported Trans fat intake: not reported MUFA intake: not reported CHO intake: not reported Sugars intake: not reported Protein intake: not reported Alcohol intake: not reported Compliance, other methods: not reported Inclusion basis: aimed to increase GLA rather than total PUFA. Aimed to increase omega‐6 by 2.1% E, assume 2.2% E increase for PUFA, > 10% of assumed 6% E PUFA baseline. No confirmatory biomarker, TC or intake data. PUFA dose: 2.2% E PUFA Duration of intervention: 40 months
Outcomes	Main trial outcome: unclear, "survival", probably mortality Dropouts: 5 (unclear from which groups) Available outcomes: mortality, cancer mortality (face flushing reported as a side effect, but no numbers provided and assumed due to concomitant pyridoxine) Response to contact: Professor McIllmurray replied, "I don't have the records...so I have nothing more than what appears in the publication. I do not recall there being any cardiovascular events."
Notes	Trial funding: not stated, Efamol Ltd provided the Efamol capsules and inert capsules. *EPO described as being ˜70% LA in some publications, this and a 1 g capsule size have been assumed where no other details are provided
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "assigned at random"
Allocation concealment (selection bias)	Unclear risk	No details
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No details apart from the placebo was identical in appearance to the Efamol capsules
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	5 dropouts, unclear from which arms
Selective reporting (reporting bias)	Unclear risk	No protocol or trials register entry found
Attention bias	Low risk	Supplement provided, no suggestion of attention bias
Compliance	Unclear risk	Neither tissue PUFA biomarkers nor TC data reported
Other bias	Unclear risk	None noted, but contents of placebo capsules unclear