HEAD & NECK

Understanding the Anatomy

Distant metastases in head and neck cancer are defined as tumor cells that arise from a primary tumor in the head and neck and then spread to a location outside of the head and neck.

While tumor cells can spread anywhere in the body, the most common sites of distant metastases in head and neck cancer are shown here1, Ferlito A, Shaha AR, Silver CE, Rinaldo A, Mondin V. Incidence and sites of distant metastases from head and neck cancer. O RL J Otorhinolaryngol Relat Spec. 2001;63(4):202-207.9 Leemans CR, Tiwari R, Nauta JJ, van der Waal I, Snow GB. Regional lymph node involvement and its significance in the development of distant metastases in head and neck carcinoma. Cancer. 1993;71(2):452-456.:

Exactly how tumor cells travel from one site in the head and neck to another site in the body is not totally clear, but there are a few theories.2 Allen CT, Law JH, Dunn GP, Uppaluri R. Emerging insights into head and neck cancer metastasis. Head Neck. 2012 doi: 10.1002/hed.23202. [Epub ahead of print]. One is that tumor cells from the primary tumor drain into the lymphatic system and enter regional (or neck) lymph nodes. Once in a lymph node, the tumor cells can then access the bloodstream (and thus distant sites throughout the body) either through the lymph node itself or when the lymphatic fluid passes through the lymph node and drains into the veins.

Another theory is that tumor cells enter the bloodstream from around the primary tumor itself. Then the cells can be deposited in different parts of the body and develop into a clinically evident distant metastasis. This theory is supported by those rare cases in which there is no cancer in the lymph nodes, but the cancer appears in a distant site in the body.

While the medical community doesn’t know exactly why some cancers spread to a distant part of the body and others do not, doctors have found some risk factors for developing distant metastases9, Leemans CR, Tiwari R, Nauta JJ, van der Waal I, Snow GB. Regional lymph node involvement and its significance in the development of distant metastases in head and neck carcinoma. Cancer. 1993;71(2):452-456.10 Alvi A, Johnson JT. Development of distant metastasis after treatment of advanced-stage head and neck cancer. Head Neck. 1997;19(6):500-505.:

• Extension of tumor outside of the lymph node capsule
• Invasion of the jugular vein
• Positive lymph nodes
• A high N stage and/or more than three positive lymph nodes in the neck
• Positive lymph nodes lower in the neck
• Positive margins at the primary tumor site