ROOSEVELT - A Roosevelt man filed a lawsuit today, claiming he was treated for years by a phony doctor who failed to detect his cancer. Nevely Plumber says he was treated by John E. Mitchner at a health clinic that's affiliated with Nassau University Medical Center (NUMC). Plumber says Mitchner led him to believe he was a doctor, performed several blood tests and told him time after time that he was in perfect health. Plumber says he was recently diagnosed with agressive prostate and bone cancer and now goes for weekly treatments at the Memorial Sloan Kettering Cancer Center. He says Mitchner never performed the necessary rectal exam to detect the prostate cancer.While Mitchner is licensed in New York as a physician's assistant, hospital officials say he does not have a license to practice as a medical doctor. In a statement, the NuHealth System, which NUMC is a part of, says Mitchner has been employed by them as a physician's assistant since late 2010.NuHealth also says there is no record at the clinic of Plumber being a registered patient or having ever had blood work performed.