Patent ID: 7659057

Claim:
A prognostic/diagnostic method for detecting and diagnosing cancerous and precancerous tissue, the method comprising, in combination and in sequence, the steps of: (a) topically applying to epithelial tissue a dye that selectively stains cancerous and precancerous tissue to locate suspect tissue, wherein the dye comprises: (1) conformational isomers of toluidine blue O, the compounds having the structures (2) N-demethylation derivatives of the isomers, the compounds having the structures a ratio of combined areas of 254 nm HPLC peaks representing the isomers to combined areas of 254 nm HPLC peaks representing the N-demethylation derivatives being at least about 6:1; (b) separating cells from the suspect tissue; and (c) subjecting the cells to molecular analysis to determine whether the separated cells exhibit characteristics associated with cell differentiation or cancer.