Table 1. Characteristics of the included studies.

No	First author	Region	Year	Study design	Sample size	Index	Regimen	outcome
1	Maria V. Grau	US	2006	Case-control study	702 cases; 1019 controls	Adjusted OR	NSAIDs	SCC, BCC
2	Mary C. Clouser	US	2009	Cohort study	321 any NSAID uesers; 1081 no NSAID users	Adjusted HR	NSAIDs, aspirin only, non-aspirin	SCC, BCC
3	Maryam M. Asgari	US	2010	Case-control study	415 with SCC; 415 controls	Adjusted OR	NSAIDs, aspirin only, non-aspirin, celecoxib	SCC
4	Craig A. Elmets	US	2010	RCT	122 celecoxib group;118 placebo group	RR	celecoxib	SCC, BCC
5	Dorothea C. Torti	US	2011	Case-control study	535with SCC; 487 with BCC; 462 controls	Adjusted OR	NSAIDs, aspirin only	SCC, BCC
6	Elizabeth K. Cahoon	US	2011	Cohort study	2291 with BCC; 55922 without BCC	Adjusted HR	NSAIDs	BCC
7	Johannesdottir SA	Denmark	2012	Case-control study	1974 with SCC; 13316 with BCC; 178655 controls	Adjusted OR (incidence rate ratio)	NSAIDs, celecoxib	SCC, BCC
8	J. M. Jeter	US	2012	Cohort study	92125 Caucasian women	Adjusted RR	aspirin only, non-aspirin	SCC, BCC