Cancer screening is meant for healthy people with no symptoms at all. If you have symptoms, you should tell your doctor.
Screening looks for early signs that could mean cancer is developing. It can help spot cancers at an early stage, when treatment is more likely to be successful and the chances of survival are much better. In some cases, it can even prevent cancers from developing at all, by picking up early changes that can then be treated to stop them turning into cancer. This is how cervical screening prevents cervical cancer.
Screening has harms as well as benefits so make sure you read the leaflet that comes with your invitation to help you decide.
Screening programmes can only be set up for a particular cancer type if it will save lives without harming too many people. For the current bowel, breast and cervical screening programmes there is evidence that benefits outweigh the harms.
There is no screening programme for prostate cancer because the PSA test is not reliable enough, but men over 50 can talk to their doctor about the test.