No association between gallbladder polyps and long-term risk of gallbladder cancer

May 2020 Science Eline Feenstra

Gallbladder polyps (GP) are found in more than 4% of adult abdominal ultrasonographs. However, their growth pattern and association with gallbladder cancer (GBC) are poorly defined. A new study published in JAMA network open shows that there is no association between GP and the long-term risk of GBC.

The aim of the study was to determine the growth pattern of GPs and their association with GBC. This cohort study included 622,227 adult members. Of this group, 365 people had GBC prior to the ultrasound (267 [73.1%] women; 173 [47.4%] white patients; median age, 71 [61-79] years). The number of patients with GP was 35,970 (18,645 (52.0%) women, a median age of 50 (40-60) years, and 15,573 (43.3%) white patients).

Gallbladder cancer diagnosis

GP were found in 22 patients (6.0%) in the GBC cohort and in 35,870 of 622,227 adults (5.8%) who underwent abdominal ultrasonography. Of these, 19 (0.053%) were diagnosed with GBC, similar to those without GP (316 of 586,357 [0.054%]). The unadjusted GBC rate per 100 000 person-years was 11.3 (95% CI, 6.2-16.3) overall and increased with polyp size. In those observed for at least 1 year, the rate was 3.6 (95% CI, 0.7-6.5) per 100 000 person-years.

Polyp growth

In 6359 patients with evaluable follow-up, unadjusted cumulative probabilities of polyp growth of at least 2 mm at 10 years were 66.2% (95% CI, 62.3%-70.0%) in polyps initially less than 6 mm and 52.9% (95% CI, 47.1%-59.0%) in polyps initially 6 mm to less than 10 mm. Despite this, gallbladder cancer rarely occurred in those with gallbladder polyps, with an overall rate of 11.3 per 100 000 person-years and, among patients observed for at least 1 year, a rate of 3.6 per 100 000 person-years.

In this study, GBC rates were low and similar among patients with and without GPs. Growth of 2 mm or more appeared to be part of GP natural history. The results call into question the strategy of proactively following GP to detect GBC.

Source

JAMA network open

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