Review: Cancer Diagnosis

Here is what we have learned from Cancer Diagnosis

  • A biopsy (removal of tissue for microscopic evaluation) is preferred to establish, or rule out, a diagnosis of cancer.
  • Usually, a biopsy, together with advanced imaging technologies, can not only confirm the presence of cancer, but also pinpoint the primary site and secondary site(s) of the cancer, if any. A cancer's primary site may determine how the tumor will behave; whether and where it may spread, or metastasize; and what symptoms it is most likely to cause. A secondary site refers to the body part where metastasized cancer cells grow and form secondary tumors.
  • Once a cancer has been confirmed, the pathologist often assigns a pathological grade to a tumor according to how malignant the tissue looks under the microscope. Cancers are further classified according to stage.

Suggested Citation

SEER Training Modules: Review: Cancer Diagnosis. U.S. National Institutes of Health, National Cancer Institute. Cited 20 December 2025. Available from: https://training.seer.cancer.gov.