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

Table 11 Descriptive characteristics of studies on the association between cholecystectomy and distal colon 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
Nogueira et al[21], 2014	1992-2005	Case-control	986/40996	2572/100000	Medicare database	Cancer registry	> 6	OR = 0.93 (0.86-1.00)	Age, gender	49
Todoroki et al[67], 1999	1991-1994	Case-Control	87/965	270/2129	Medicare database and self report	Cancer registry	≥ 2	OR = 0.8 (0.6-1.1)	Age, gender, Family history, BMI, diet, NSAID use	48
Zeng et al[62], 1993	1965-1986	Case-Control	2/131	18/2188	Hospital records	Hospital records	≥ 2.5	OR = 1.87 (0.43-8.14)		26
Friedman et al[63], 1987	1971-1984	Case-Control	60/1963	773/27687	Medicare database	Cancer registry	≥ 2	OR = 1.2 (0.9-1.6)	Age, gender, geographical area, calendar year	47
Schernhammer et al[59], 2003	1982-1998	Cohort	28/6669	78515	National database of nurses	Self-report and National death registry	16	RR = 0.95 (0.64-1.43)	Age, smoking, BMI, lifestyle factors, comorbidities	57
Lagergren et al[51], 2001	1965-1997	Cohort	2564/278460	NA	National registry	National registry	10	SIR = 0.98 (0.94-1.02)	Age, gender, time after cholecystectomy	35

NA: Not available; BMI: Body mass index; NSAIDs: Nonsteroidal anti-inflammatory drugs.