Table 1.

Characteristics of included animal studies.

Author, Year	Animal Model	Baseline Diet(s)	Dietary Tomato and/or Lycopene Content *	Length of Intervention	Primary Findings
Canene-Adams, 2009 [27]	Dunning R3327-H transplantable tumors (Copenhagen rats)	AIN-93G-based diets fed; ad libitum	10% TP (providing 13 nmol lycopene/g diet and resulting in 511 nmol/g serum lycopene), 23 nmol/g diet supplemental lycopene beadlet (252 nmol/g serum lycopene), or 224 nmol/g diet supplemental lycopene beadlet (884 nmol/g serum lycopene)	18 weeks after tumor transplantation	No differences in serum testosterone or DHT between rats fed tomato, lycopene, or control diets
Limpens, 2006 [28]	Xenograft using PC-346C cells (athymic mice)	821077 CRM(P) low (but adequate) vitamin E rodent diet; ad libitum	5 or 50 mg/kg BW lycopene (from LycoVit) oral gavage = 0.5–1.5 mg lyco/day	42 days after tumor inoculation	No differences in plasma PSA between mice given control or lycopene gavages (PSA levels were proportional to tumor size regardless of intervention)
Lindshield, 2010 [29]	Dunning R3327-H transplantable tumors (Copenhagen rats)	AIN-93G-based diets; ad libitum	250 mg/kg diet supplemental lycopene beadlet = 5 mg lyco/day	18 weeks after tumor transplantation	No differences in serum testosterone or DHT between rats fed lycopene or control diets
Siler, 2004 [30]	MayLyLu Dunning transplantable tumors (Copenhagen rats)	Kliba #2019 with added coconut fat (6%), <5 ppm vitamin E, reduced (but adequate) vitamin A, and devoid of phytosterols; did not indicate if ad libitum	200 ppm lycopene (1.02 µM plasma lycopene)	4 weeks on diet prior to tumor transplantation, then 18 additional days	Lycopene supplementation reduced tumor expression levels of SRD5A1 and androgen-target genes (cystatin related proteins 1 and 2; prostatic spermine binding protein; prostatic steroid-binding protein C1, C2, and C3; probasin) (only fold reductions reported—no other statistical values reported)
Wan, 2014 [31]	Transgenic (TRAMP mice)	AIN-93G -based diets; did not indicate if ad libitum	10% TP (providing 384 mg lycopene/kg diet) or 462 mg/kg diet supplemental lycopene beadlet (0.36 µM plasma lycopene) = 3–4 mg lyco/day	4 weeks diet prior to surgery, then 12 additional days	Reduced prostatic expression of genes related to androgen metabolism by tomato feeding (SRD5A2 (p = 0.04), Pxn (p = 0.04), and Srebf1 (p = 0.05)) and lycopene supplementation (SRD5A1, p = 0.03)

* All treatments can lead to blood levels of lycopene within a physiological range (~1 µM). Abbreviations: TRAMP (transgenic adenocarcinoma of the mouse prostate); TP (tomato powder); BW (body weight); DHT (dihydrotestosterone); PSA (prostate-specific antigen); SRD5A1 and 2 (5 α-reductase type 1 and 2); Pxn (paxillin); Srebf1 (sterol regulatory element binding transcription factor 1).