Signs and symptoms a person is having or the results of imaging or other tests might suggest cancer, but usually a biopsy (or sometimes a cytology test) is needed to know for sure.
A diagnosis of cancer is nearly always made by a pathologist – a doctor with special training to look at samples of cells or tissues under a microscope. They may also do tests on the cells’ proteins, DNA, or RNA to help tell if there’s cancer or to learn more about the cancer. If cancer is found, the results of these tests can also sometimes help determine the best treatment options.
Tests of cells and tissues can find many other kinds of diseases, too. If you are waiting on biopsy results, it’s important to know that not all lumps are cancer.