There is no single, simple method to diagnose cancer. It may take several months or years for malignant cells to multiply to the point where they can be detectable cancer.​

Cancer symptoms depend on its location and unfortunately it is possible for cancer to become widespread before it starts to produce any symptoms at all. Sometimes cancers may be discovered accidentally during routine tests or the investigation of non-specific symptoms.​

Easiest  cancers to detect are

• Those that are on the skin and which show a change in a mole or wart. Those that start close to the surface and can be seen or felt as a lump or thickening.
• Relatively easy to examine for early signs of cancer such as the mouth and throat, the cervix and vagina or the rectum and anus.

The final cancer diagnosis is based on a pathologist’s opinion. Different cancers are discovered in different ways. Detecting cancer, or cancer diagnosis, always entails detailed examination.