Late effects are side effects of cancer treatment that become apparent after your treatment has ended. Cancer survivors might experience late effects of cancer treatment a few months after treatment is completed or years later.

It isn’t clear why these late effects are delayed. Some doctors believe that late effects simply weren’t noticed during and immediately after your treatment, though the damage may have been there all along. It could be that your body was compensating for the damage caused by cancer treatment and is no longer able to do that, revealing these late effects.

In contrast with late effects, side effects that start during your cancer treatment and linger for months or years after are called long-term side effects. Long-term side effects usually are different from late side effects. For example, nerve damage (peripheral neuropathy) is common during some types of chemotherapy and may begin during treatment and linger for months or even years after cancer treatment are completed. Most long-term effects lessen or completely resolve with time.

Some cancer survivors wonder why they weren’t told about the possibility of long-term or late side effects before they began treatment. Sometimes cancer survivors were told, but with so much to remember and go through when you’re first diagnosed and beginning treatment, it’s easy to forget or not absorb all the information. Sometimes your doctor doesn’t discuss late side effects because it’s impossible to predict every single side effect, early or late, that some treatments have. It’s also possible that the late effects of your treatment weren’t known at the time you began treatment.