When you have cancer why do you get lots of mucas from your nose?

Not sure! I'm not sure what kind of cancer you mean. Having lots of mucous from your nose isn't a sign of most cancers. Some cancer treatments, like chemotherapy, can cause your nose to run. That's because the chemo harms the little hairs in your nose that normally keep mucous from dripping out. If you can give more specifics in another question, maybe i can help you more!