Incidental gallbladder cancer (found after cholecystectomy)

This is the UK baseline for the incidental cancer pathway: a re-resection rate well above the Dutch registry's 24 percent, with the same selection caveat. The UK layer of this deep dive should read the full paper for the histology, referral and timing detail the abstract leaves out.

It softens the Ethun four-to-eight-week rule: timing within the range that services can deliver probably matters less than completing the operation at all and doing it with the liver bed and nodes cleared.

The rationale for OPT-IN and GAIN in one place. Until OPT-IN reports in 2028 the neoadjuvant approach for incidental cancer remains a reasoned choice rather than a proven one.

The best single starting point for a clinician or researcher new to the disease, written by the groups running the Chilean and Indian cohorts; its list of unmet needs is the skeleton of the ideas section on this page.

Six per thousand is the number behind the debate on routine versus selective histology of gallbladder specimens: applied to a national cholecystectomy volume it predicts a few hundred unsuspected cancers a year in a country the size of England.

GAIN closed in October 2024 with 68 participants according to ClinicalTrials.gov, one fifth of its target: the clearest example of how hard it is to run a randomised surgical trial in incidental gallbladder cancer, and why OPT-IN's result matters.

A whole-country picture of the gap between guideline and practice: three quarters of eligible patients never reached the second operation. The survival difference is confounded by selection but the residual disease rate is not.

The UK-authored summary that most NHS hepatobiliary units work from; it names the open questions (type, extent and timing of re-resection; adjuvant chemotherapy) that the trials in this roadmap are trying to answer.

The strongest data against routine re-resection for T1b tumours, which guidelines still recommend. A prospective study or registry with standardised pathology is the missing step; the authors' own conclusion is that extended cholecystectomy is not needed for T1b.

The origin of the widely quoted four-to-eight-week window for re-resection. A 2026 individual patient data meta-analysis found no survival difference by timing, so the window is a reasonable planning target rather than a proven rule.

This is the observational backbone of the rule that T1b or deeper incidental cancers should be re-resected, and of resecting the bile duct only when the cystic duct margin is positive.

Depth of invasion has been the organising principle of gallbladder cancer staging ever since, through the TNM editions to the 2017 T2a/T2b split; and the observation that most cases are incidental was already true fifty years ago.