Table 2.

PubMed database outcomes.

PMID	Condition	Intervention	Subject	Endpoint	Size	Results
26488693	NMSC	Oral nicotinamide	With history of NMSC	New NMSC	386	Oral nicotinamide was safe and effective in reducing the rates of new NMSC and actinic keratoses in high-risk patients [32].
27061568	NMSC	Oral nicotinamide	Organ transplant recipients with history of NMSCs	Rate of NMSC	22	Oral nicotinamide was associated with a statistically nonsignificant relative difference in the rate of NMSCs and statistically nonsignificant reduction in AK [33].
36856616	NMSC	Oral nicotinamide	Organ transplant recipients with history of NMSCs	Rate of NMSC	158	Oral nicotinamide did not lead to lower numbers of NMSC or AK in immunosuppressed solid-organ transplant recipients [34].
30244097	Skin immunity	Oral nicotinamide	Immunocompetent patients who had NMSCs	Immunological markers	78	The study found significant decrease in the number of macrophages in keratinocytes that arose in patients receiving nicotinamide compared to placebo [35].
20051370	BCC	Oral celecoxib	PTCH1(+/−) patients with BCNS	Rate of BCC	60	Celecoxib decreased the development of new BCCs in all subjects, but it did not reach statistical significance [20].
21115882	NMSC	Oral celecoxib	History of AK	Incidence of SCC, BCC, and AK	240	Celecoxib might be effective for prevention of SCCs and BCCs in individuals who had extensive actinic damage and were at high risk for development of NMSC [36].
35395069	Melanoma	Oral aspirin	Elderly	Rate of melanoma	19,114	Aspirin was not associated with a reduced risk of invasive melanoma in older individuals [37].
21688346	NMSC	NSAIDs	Veterans with higher risk of NMSC	Rate of SCC and BCC	728	This study did not identify a negative association between NSAIDs and keratinocyte carcinomas [38].
29570772	BCC	Aspirin and/or folic acid orally	Diagnosed with colorectal adenomas	Rate of BCC	1121	Neither aspirin nor folic acid treatment had a statistically significant effect on risk of BCC. Subgroup analysis suggested that chemopreventive NSAIDs may be specific to those at high risk for BCC [39].
20000874	NMSC	Topical piroxicam	With history of AK	Actinic Keratosis Erythema Scale Atrophy score	31	The use of piroxicam 1% gel for 90 days induced complete regression in 48% of evaluated actinic keratoses [40].
23348836	SCC	5-FU; angiotensin-converting enzyme inhibitors or angiotensin receptor blockers	Veterans with history of NMSC	Rate of SCC	1131	Key risk factors for additional SCCs in patients with multiple prior NMSC was identified [41].
29505863	NMSC	Topical 5-FU	Veterans with high risk of NMSC	Cost	932	There was a significant cost savings for patients treated with 5-FU [42].
33795573	NMSC	Topical 5-FU	History of AK	Rate of NMSC	932	A single 2- to 4-week course of topical 5-FU to the face and ears decreased overall biopsy rates for 1 year. SCC biopsy yield was decreased in the first year after treatment. There was a nonsignificant trend toward increased BCC biopsy yield [43].
30896781	BCC	Topical 5-FU	Veterans with high risk of NMSC	Rate of BCC	932	5-FU might be effective for the prevention of superficial subtype of BCCs even though there was no effect on BCCs overall [44].
34988975	SCC	Topical 5-FU	Organ transplant recipients	Rate of	40	Trials of topical AK treatments for SCC chemoprevention are feasible [45].
21463984	NMSC	Topical potassium dobesilate	History of AK	Lesions of actinic keratosis	30	The use of potassium dobesilate 5% cream for 16 weeks induced complete regression in 70% of evaluated actinic keratoses [46].
35533029	NMSC	Metformin and sulfonylureas	Diabetic patients with history of NMSC	Rate of NMSC	932	Diabetic patients at high risk for KC might benefit from the use of metformin versus sulfonylureas [47].
24441673	BCC	Topical tazarotene (a retinoid)	Patients who have BCNS	Rate of BCC	34	The study provided no evidence for either chemopreventive or chemotherapeutic effect of tazarotene against BCCs in patients with BCNS [48].
24614012	Melanoma	Oral lovastatin for 6 months	Subjects with at least two clinically atypical nevi	Biomarkers of melanoma	80	There were no effects. Further research into pathogenesis of melanoma and other chemopreventitive agent is needed [49].
29691233	Melanoma	Sulforaphane with administration of oral broccoli sprout extract	Patients had at least 2 atypical nevi and a prior history of melanoma	Safety; plasma and skin drug levels; biomarkers	17	Oral BSE-SFN was well-tolerated at daily doses up to 200 µmol and achieved dose-dependent levels in plasma and skin. Efficacy studies may be performed in the future [50].
20103724	Unspecified	Topical perillyl alcohol (POH)	Individuals with sun-damaged skin.	Skin histopathologic scores and nuclear chromatin pattern	89	Karyometric analyses could detect a modest effect of POH in sun-damaged skin. Improved delivery into the epidermis may be necessary [18].