Obesity and cholangiocarcinoma

Table 1 Epidemiologic studies assessing obesity as a potential risk factor for cholangiocarcinoma

Ref.	Study design	Type of CC	Study findings	Study limitations
Welzel et al[52]	Case-control	ICC and ECC	Positive association between obesity and ICC; no association between obesity and ECC	Only included age ≥ 65 yr; database limitations; possible diagnostic bias
Welzel et al[53]	Case-control	ICC	No association between obesity and ICC	ECC not included
Grange et al[54]	Case-control	NS	Positive association between obesity and cholangiocarcinoma	Type of CC not specified; diagnosis subject to misclassification
Oh et al[55]	Cohort	NS	Positive association between obesity and cholangiocarcinoma	Does not distinguish ECC and ICC; included only males; database limitations

CC: Cholangiocarcinoma; ECC: Extrahepatic cholangiocarcinoma; ICC: Intrahepatic cholangiocarcinoma; NS: Not stated.