It has not been thought that UVB treatments pose any risk for skin cancers except on male genitalia. One study reported, however, that melanoma developed in human tissue exposed to UVB radiation, raising doubts about the safety of this treatment. Some experts postulate, on the other hand, that UVB therapy may actually have protective properties, since doses are generally low and it causes the skin to thicken but does not burn the skin, a primary trigger for skin cancer. When used without medication, UVB treatment can be administered in the physician's office or even at home with equipment obtained using a physician's prescription. Even at home, treatment must always be supervised, however.
Full results take about three weeks.
Maintenance treatment twice weekly for one to two months and then once a week for about four months is effective in preventing relapse. This combined therapy requires a full eight hours for a single treatment, which may need to be administered daily for two to four weeks. Psoralen increases the skin's sensitivity to UVA radiation and is administered before the treatment starts. It is usually taken orally. People should avoid this treatment if they are taking drugs or have conditions that cause them to be light sensitive.