Metastasis

Synonyms

Secondary tumor; Tumor spread

Definition

Metastasis is the growth of a tumor at a site not physically connected to the primary tumor.

Characteristics

The presence of metastasis is a key feature in determining the prognosis and the treatment strategy for any cancer patient. The probability that a patient will have a metastasis varies widely depending upon the type of cancer. Squamous cell carcinoma of the skin rarely metastasizes, but squamous cell carcinoma of the lung frequently does. An important part of the clinical workup for every patient who is diagnosed with cancer is an evaluation for metastasis. The presence and extent of metastases are a critical component of clinical Staging systems that clinicians use to choose appropriate therapy and to judge prognosis.

Metastases follow different routes that can be broadly classified into three. One is metastasis to the regional lymph nodes or lymphatic metastasis. This involves colonization of draining lymph nodes. The second is...