Table 2.

A summary of differentiating agents, along with the target diseases.

Differentiating Agent	PpIX Accumulation Mechanism	Diseases Treated	References
Vitamin D	Increases coproporphyrinogen	breast cancer, squamous cell carcinoma, melanoma, actinic keratosis, prostate cancer	(191, 192, 203, 211–213)
5-Fluorouracil	Increases coproporphyrinogen	actinic keratoses, melanoma, cervical cancer, mucosal lesions, intraepithelial squamous cell carcinoma	(193–197)
Iron Chelators	Decreases ferrochelatase	lung and normal fibroblasts, epidermal, pancreatic, bladder, colon, urothelial and skin carcinoma, adenocarcinoma carcinomas, basal cell carcinoma, solar keratoses, and lesions of Bowen’s disease	(198–202, 204–210)
Androgens	Decreases ferrochelatase	prostate cancer, breast cancer	(211, 214)
Methotrexate	Increases coproporphyrinogen	prostate cancer, buccal precancers, cervical cancer, head and neck cancer	(215–217)