Cancers affecting organs in the digestive system often have no symptoms in the early stages, but could be treated if they are identified early enough. It's important, therefore, to be screened regularly.
Cancer screening procedures look for cancer before a person has any symptoms so that intervention and treatment can improve outcomes. By the time symptoms appear, the cancer may have grown or spread, making it harder to treat.
Some screening procedures are recommended only for people who have risk factors that make it more likely they will develop cancer. Other screening procedures are recommended for all people at a certain age.
Tests and procedures that are considered diagnostic, on the other hand, are only performed to detect diseases once symptoms have presented. These tests help providers rule out or confirm suspected conditions.