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The follow-up strategy for patients with gallbladder polyps should be based on the size of the lesions, which can influence progression and malignancy potential, British researchers advised.

In a retrospective analysis done at a tertiary care hepatobiliary center, polyps that increased in size during surveillance were significantly larger at baseline than those that remained stable (7 mm versus 5 mm in diameter, P<0.05), according to Giuseppe Garcea, MD, and colleagues from University Hospitals of Leicester in Leicester, England.

And polyps greater than 10 mm at baseline were more likely to be malignant or potentially so, with an area under the curve of 0.81 (P<0.001), the researchers reported online in Archives of Surgery.

The rarity of gallbladder polyps and an incomplete understanding of their natural history -- coupled with the fact that the vast majority are benign and only a few are adenomatous -- has led to uncertainty as to the optimal therapeutic approach.

In addition, ultrasound evaluation of the gallbladder presents difficulties, and many purported polyps turn out to be stones on the gallbladder wall or cholesterol polyps.

Therefore, in an attempt to clarify which patients should undergo removal of the gallbladder, which need surveillance, and which require little or no follow-up, Garcea's group reviewed the case notes from 986 patients seen at their center between 2000 and 2011.

More than half were women, and the median age was slightly over 57 years.

A total of 69% of the polyps were smaller than 5 mm, 26.2% were 5 to 10 mm, and the remaining few were larger than 10 mm.

A single polyp was present in 62%, while more than three were detected in 24.4%.

Median follow-up was 39.3 months, but half of the patients received no subsequent surveillance or follow-up.

An increase in size was seen in only 6.6% of polyps during the surveillance period, while a decrease was seen in 25.7% and no change occurred in 67.7%.

Among patients who underwent cholecystectomy, the most common reasons were persistent pain and polyp size in excess of 10 mm.

Following gallbladder removal, only 3.7% turned out to be possibly malignant on histologic evaluation, and only one specimen showed actual malignant changes.

The researchers then considered the potential cost-effectiveness of surveillance in patients with these polyps.

In the U.S., the overall economic burden associated with gallbladder cancer is $78 million yearly, they calculated.

Given the median age of 57 at the time of polyp detection, and a 20-year subsequent life expectancy, ultrasound surveillance every 2 years could carry a price tag of $47,036 each year and $9.4 million over 2 decades.

They further determined that biannual surveillance could save 5.4 lives each year, if all potentially neoplastic polyps were assumed to become malignant.

And if 30% of patients undergoing surveillance had surgery, as was the case in this cohort, annual costs for surgery would be $253,115, rising to $310,167 when surveillance costs are also included.

With annual costs of $94,069 for a single patient with gallbladder cancer, the saving of surveillance would be approximately $207,839 per 1,000 patients each year, they estimated.

They suggested that surveillance might be more cost-effective if only done for polyps 5 mm or more, and among groups such as Asians who have higher risks for gallbladder malignancy.

In an invited critique, Jonathan Koea, MD, of North Shore Hospital in Auckland, New Zealand, noted a caveat to these findings.

"Surveillance is only cost-effective when there is a high prevalence of adenomatous lesions within the polyp population -- something with current imaging techniques we cannot yet be sure of," he observed.

Garcea and colleagues concluded that polyps smaller than 5 mm "can probably be ignored," while resection should be done for those larger than 10 mm or increasing in size, and surveillance is in order for those between 5 mm and 10 mm.

But they deemed their finding that almost half of patients had no further follow-up after the detection of a polyp as "perhaps alarming."

They suggested that for young patients, cholecystectomy might be considered even with polyps smaller than 10 mm, because of the lengthy and possibly "unsustainable" surveillance that would be needed.

Finally, "all gallbladder polyps represent potentially premalignant disease and require discussion at a hepatobiliary multidisciplinary team meeting because this would enhance and standardize the management of this condition," they cautioned.