Cholecystectomy and the risk of alimentary tract cancers: A systematic review

Table 3 Descriptive characteristics of studies on the association between cholecystectomy and gastric cardia cancer

Ref.	Period of study	Study design	No. of cases	No. of controls	Exposure ascertainment	Outcome ascertainment	Follow-up (yr)	Effect estimate	Adjustments	Quality of publication
Freedman et al[20], 2000	1994-1997	Case-control	262	820	Self-report	Pathology	-	RR = 0.67 (0.39-1.13)	Age, gender, alcohol, smoking, BMI, physical activity, education, diet	37
Nogueira et al[21], 2014	1992-2005	Case-control	122/5579	2572/100000	Medicare database	Cancer registry	> 6	OR = 0.88 (0.73-1.06)	Age, gender, diabetes	49
Fall et al[28], 2007	1970-1997	Cohort	94/251672	NA	National registry	Cancer registry	11.5	RR = 0.95 (0.76-1.16)	Age, gender, surgical procedure	42

NA: Not available; BMI: Body mass index.