New research sheds light on why cervical precancers disappear in some women and not in others. Scientists at the Johns Hopkins Kimmel Cancer Center report in the July 1 issue of Clinical Cancer Research that the reason many of these lesions persist is an unlikely mix of human papilloma virus (HPV) strain and a woman’s individual immune system. For decades, scientists have known that HPV causes nearly all cases of cancer in the neck of the womb. Most sexually active women some reports say up to 80 percent are exposed to HPV and more than half of these women are infected with strains of the virus that could likely turn a precancerous lesion to cancer. But only a small percentage of precancers progress to full-blown cancer, a process that takes years.