The relationship between cancer and metastasis
Not all cancers metastasize, and it is very rare for benign tumors to metastasize. Cancers that don’t metastasize are called carcinoma-in-situ. Naturally, this is a stage in all cancers before metastasizing, but some cancers very rarely metastasize, as in the case of basal cell carcinoma which only grow at the face, destroying its structures.
On the other hand, some cancer only present clinically by their metastases and are called occult carcinomas. The reason for this is that the primary tumor is found in a hidden place where it doesn’t produce any symptoms. Examples of these tumors include nasopharyngeal cancer, some types of esophageal cancer and some types of lung cancer. The fact that these tumors mostly present by metastases makes their outcome grim.