Growth rate and malignant potential of small gallbladder polyps--systematic review of evidence

The overall aim of this systematic review was to determine whether ultrasound (US) follow up for gallbladder polyps (GBPs) measuring less than 10 mms is necessary.

A search was performed in MEDLINE and EMBASE between January 1976 and January 2012 using keywords: gallbladder, polyps, neoplasm, cancer, tumour, carcinoma, malignant, adenoma. Included were studies involving adult patients, examined with transabdominal US at least twice. The outcomes of included studies were gallbladder polyp growth as demonstrated on US over time, followed where available by histological examination of cholecystectomy specimens.

Ten studies met the inclusion criteria for the review. Altogether 1958 subjects with mean age between 41.5 and 59 years were followed up with US. The percentage of GBPs which showed growth over the follow up period ranged from 1% to 23%. 43 neoplastic polyps were found in total irrespective of size, 20 of which were malignant and at least 7 of those were >10 mms. At least 7 malignancies were present in polyps <10 mms but it was unknown if they had undergone growth on follow up.

Level II-2 and below evidence on rate of growth of small GBPs <10 mms exists in the literature. It indicates that growth does occur in a significant minority of small GBPs, but it is slow. Due to deficient reporting and small numbers of cases, the correlation between growth of GBP and development of malignancy cannot be established using currently available evidence. Malignancy can be present in polyps <10 mms although it is significantly more frequent in polyps >10 mms. Cholecystectomy for symptomatic GBPs irrespective of their size, alongside the current practice for removal of gall bladders containing asymptomatic polyps >10 mms, is proposed. No evidence based US follow up schedule can be recommended at present for asymptomatic polyps <10 mms, and in its absence an intuitive follow up with US is likely to continue.