Mode of spread of thyroid cancer.

Metastatic dissemination of differentiated cancer was studied in a personal group with the following results. Invasion of cancer to adjacent structures can be encountered even in children with typical increase with age. The lymphatic spread to regional lymph nodes is typical of papillary cancers and in young patients. The same type of spread without the age-dependent decrease can also be proved, with lower incidence, in follicular cancers. Pulmonary metastases are frequently the only type of distant metastases and may originate from previous spread to lymph nodes. The isolated bone metastases a;e probably brought about through the vertebral venous system. Patients having multiple bone metastases or both bone and lung lesions are probably the only typical examples of metastasizing through the systemic blood flow. As the above types of distant metastases carry different prognosis they should also be recognized by the TNM system.