Three-quarters of cancer patients have insufficient levels of vitamin D and those with the lowest levels have the most advanced cancer, U.S. researchers say. Lead author Thomas Churilla, a medical student at the Commonwealth Medical College, Scranton, Pa., said the study involved 160 patients with a median age of 64 -- half women, half men. The five most common primary diagnoses were breast, prostate, lung, thyroid and colorectal cancer. The study found 77 percent of the patients had vitamin D concentrations either deficient -- less than 20 nanograms per milliliter, or sub-optimal 20 to 30 ng/mL. The median serum vitamin D level was 23.5 ng/mL, but regardless of the age or sex of the patient, levels of vitamin D were below the median predicted for advanced stage disease in the patient group. Patients found to be vitamin D deficient were administered replacement therapy, increasing serum D levels by an average of 14.9 ng/mL. \"The benefits of vitamin D outside of improving bone health are controversial, yet there are various levels of evidence to support that vitamin D has a role in either the prevention or the prediction of outcome of cancer,\" Churilla said in a statement. The findings were presented at the 53rd annual meeting of the American Society for Radiation Oncology in Miami.