According to my Dr. there are different levels of cervical dysplasia. CIN 1 is the lowest and isn't really considered technically precancerous yet. CIN II and CIN III are moderate to severe dysplasia (both), and CIN IV is cancer. That's how he explained it to me, and he drew a line diagram as well. My results showed me as beiong between II and III. My understanding was that if I hit CIN IV cancer had taken hold. Perhaps what the Dr. was telling her was that she had CIN IV which is cervical cancer? That's my best guess. As far as how they do the classes of cancer, etc. I'm not sure. If it is CIN IV then she'll need to discuss what level of treatment is required, that sort of thing. Does this make sense?
I hope things go well for your sister and I hope this information helps at least a little