When you have your first chemotherapy session the hair loss from the chemo usually occurs within 2 to 3 weeks after the first chemo session.
Hair loss is a result of the chemo and not the cancer so if you have cancer your hair won't fall out just because of the cancer but instead the hair loss will happen as a result of the chemo used to fight the cancer.
In some people who have chemotherapy to fight the cancer they lose their hair gradually a little bit at a time while other people lose the hair in larger quantities.
After you get done completely with your chemotherapy and the cancer is gone then your hair should grow back a little at a time.
But it would be much better to have the cancer gone completely and be bald than it would be to have cancer and hair.
The cancer can kill you but you can live a good life without hair.