More Questions Than Answers, but Gallbladder Polyps Likely Generate Too Much Angst

Incidental gallbladder polyps are commonly noted during abdominal ultrasonography. Most do not carry malignant potential, but the small portion that are adenomas do. Current guidelines suggest serial follow-up examinations, particularly for polyps greater than 7 mm in diameter, as well as consideration of cholecystectomy for polyps greater than 1 cm. These guidelines are based upon a surgical series demonstrating moderately high cancer rates in adenomas >1 cm in size. 

In this study from Kaiser Permanente of Northern California, gallbladder polyps were found in 6.0% (22/365) of gallbladder cancer patients with prior ultrasound studies (cohort 1) and in 5.8% (35,870/622,227) of adults who underwent abdominal ultrasonography (cohort 2). Of 35 patients with polyps and cancer, 1 polyp was seen only transiently and was unrelated, 3 had only carcinoma in situ, and 4 were described as masses; the association between polyp identification and pathology was uncertain in most. Polyp measurements were <6 mm in 68.8% of patients, 6 to 9 mm in 23.2%, and >10 mm in 8.1%. Overall, cancer rates were low and approximately equivalent in those patients with and without polyps. Slow progressive increase in size (>2 mm at 10 years) was common, more so for smaller- than moderate-sized polyps, but subsequent cancer among those observed for more than 1 year was only 3.6 (95% CI, 0.7-6.5) per 100,000 person-years. No cancers developed among the 507 patients with small polyps that grew to 10 mm or larger at 1549 person-years of follow-up.