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Assessment and Management of the Unknown Primary with Neck Disease

"Suspicious areas of mucosa (e.g., leukoplakia, erythroplasia, or mucosal irregularities seen on prior physical examination or on imaging studies) should be biopsied. If no such lesions are seen, random biopsies should be performed on mucosal sites with the known highest probability of harboring a tumor (i.e., nasopharynx, tonsil, tongue base, pyriform sinus.)"

J. Oliver Donegan

"The routine use of CT or MRI for the purpose of attempting to identify a primary site responsible for the cervical metastasis, however, is controversial. Some consider the routine use of either of these studies as unnecessary; others regard them as indispensable."

Robert P. Zitsch III

"The potential to improve management of patients with an unknown primary SCC metastatic to the neck through administration of adjuvant chemotherapy is attractive. However, there are currently no strong data to support the use of chemotherapy in this setting."

Henry T. Hoffman

Assessment and Management

of the Unknown Primary with Neck Disease

CHAPTER 61

J. Oliver Donegan

Metastatic disease in cervical lymph nodes may be the initial manifestation of cancer. Most of these patients will have an apparent primary at presentation. However despite the most exhaustive search, approximately 5 to 10% of these tumors remain undetected at the primary site.1-3

Each year, an estimated 40,000 patients with a new unknown primary tumor present in the United States.4 Most (> 85%) are adenocarcinomas. In the head and neck, approximately 60% of such occult primaries represent squamous cell carcinoma. Thirty percent are adenocarcinomas and the remainder are tumors originating in the thyroid gland, melanoma of the skin and mucosa, and poorly differentiated carcinoma.

If the metastases are from a squamous cell carcinoma, the primary is found in the head and neck region in the majority of cases.1 Metastatic adenocarcinoma most often originates in a primary tumor below the clavicles, such as in the lung, the gastrointestinal (GI) tract, the genito-urinary (GU) tract, breast, and pancreas. However, a small number of these adenocarcinomas may originate in the head and neck from the salivary glands, paranasal sinuses, and the nasal cavity.

Metastases to the cervical lymph nodes as an initial presenting event from tumors below the clavicles are quite uncommon, representing only approximately 4% of such cases. Only 1.5% of lung tumors, for example, will present in such a manner.1

Lymph nodes in zone 2 of the neck are the most common sites of metastases from an unknown primary, representing approximately 60 to 70% of cases. A significant proportion of supraclavicular lymph nodes represent metastatic adenocarcinoma and the majority of these tumors originate below the clavicles. Of known primary lesions metastatic to supraclavic-ular lymph nodes, approximately 20% only originate in the head and neck.

Several aspects of the assessment and management of patients with occult primary tumors have generated controversy and debate over the years. These issues include (1) the role of radiologic studies in identifying the primary lesion and assessment of cervical adenopathy; (2) the possible adverse effects of early open neck biopsy; (3) the value of tonsillectomy in identifying the primary lesion; (4) the question of branchiogenic carcinoma as a possible diagnosis; (5) the role of surgery, radiation, and chemotherapy in the management of these patients; (6) the advantages and disadvantages of treating the likely mucosal sites of the primary lesion; and (7) the value of random or directed biopsies at time of endoscopy.

The successful treatment of the metastatic neck disease and prevention of the primary tumor growth are the keys to patient survival. The management of a patient with an unknown primary carcinoma with metastatic disease in the neck remains a challenge to the head and neck surgeon and others including radiation therapists and oncologists involved in the management of these patients. However with appropriate evaluation and treatment, many of these patients have an excellent prognosis. Those patients with squamous cell carcinoma most of whom likely have primaries in the head and neck, can expect a favorable response to treatment especially if the nodal disease is limited. By contrast, patients with adenocarcinoma, most of which originate below the clavicles, generally have a very poor prognosis.

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