Doctors are on the verge of using vaccines to treat cancer patients, according to a new report. 'Cancer vaccines on the brink of commercial launch'found that the first such vaccine is expected to hit the market by the end of the year. Another five or six could be available by 2001. Ribi Immunochem, a US biotech company, will launch a treatment for a skin cancer called late stage malignant melanoma by late 1998, said the report released on Wednesday 15 July. The drug, called Melacine, is known as an Active Specific Immunity (ASI) vaccine.