THE PHOTOTUMORIGENIC POTENTIAL OF BROAD-BAND (270-350-NM) AND NARROW-BAND (311-313-NM) PHOTOTHERAPY SOURCES CANNOT BE PREDICTED BY THEIR EDEMATOGENIC POTENTIAL IN HAIRLESS MOUSE SKIN

The new Philips TL01 narrow-band (311-313 nn) and conventional broad-b and (e,g,, Philips TL12; 270-350 nm) sources are effective for psorias is phototherapy, for which treatment regimens are based on a predeterm ined minimal erythema dose. TL01 phototherapy treatment times are appr oximately half those with TL12 for psoriasis, whereas the cumulative e xposure doses at clearing are similar, We compared the phototumorigeni c potential of TL01 and TL12 radiation in mouse skin, Groups of albino Skh-1 hairless mice were exposed for 5 d/week at three dose levels. A t each dose level, TL12 and TL01 doses were equally edematogenic, At e ach dose level, TL01 radiation was significantly more effective at pro ducing first tumors of 1 nun in diameter and multiple tumors, At the l ower two dose levels, TL01 radiation produced a significantly greater proportion of squamous cell carcinomas, This study demonstrates that T L01 radiation is more phototumorigenic than TL12 radiation at equally edematogenically weighted doses, This is in contrast with previous rep orts that edema production by polychromatic sources is predictive of t heir phototumorigenic effect in Skh-1 mice. The absolute cumulative TL 12 dose needed to induce tumors was much less than that for TL01 radia tion, The possibility of increased tumor risk with TL01 phototherapy s hould be considered but must be balanced against the high phototherape utic efficacy of this source, short treatment times, and the low cumul ative doses necessary for clearing of psoriasis.