Objective In patients who have undergone a potentially curative resection of colorectal cancer, does a ‘second-look’ operation to resect recurrence, prompted by monthly monitoring of carcinoembryonic antigen, confer a survival benefit?

Design A randomised controlled trial recruiting patients from 1982 to 1993 was recovered under the Restoring Invisible and Abandoned Trials (RIAT) initiative.

Setting 58 hospitals in the UK.

Participants From 1982 to 1993, 1447 patients were enrolled. Of these 216 met the criteria for carcinoembryonic antigen (CEA) elevation and were randomised to ‘Aggressive’ or ‘Conventional’ arms.

Interventions ‘Second-look’ surgery with intention to remove any recurrence discovered.

Primary outcome measure Survival.

Results By February 1993, 91/108 patients had died in the ‘Aggressive arm’ and 88/108 in the ‘Conventional’ arm (relative risk=1.16, 95% CI 0.87 to 1.37). By 2011 a further 25 randomised patients had died. Kaplan-Meier analysis showed no difference in long-term survival.

Conclusions The trial was closed in 1993 following a recommendation from the Data Monitoring Committee that it was highly unlikely that any survival advantage would be demonstrated for CEA prompted second-look surgery. This conclusion was confirmed by repeat analysis of survival times after 20 years.

Trial registration number ISRCTN76694943.