General Information
The diagnosis of an occult primary tumor is made only if no primary tumor is
detected after careful search and does not appear during therapy. Patients
with cervical lymph node metastases histologically related to a previously
treated primary tumor and patients with lymphomas and adenocarcinoma are
excluded. If the biopsy is an undifferentiated carcinoma (in particular, a
lymphoepithelioma), the most probable primary site is in Waldeyer ring; for
example, the nasopharynx, base of tongue, or tonsil. Most epidermoid
carcinomas metastatic to lymph nodes of the upper half of the neck will
originate from a head and neck primary site. Squamous carcinomas metastatic to
the lower neck may represent a primary site in the head and neck, esophagus,
lung, or genitourinary tract. A search for primaries in these areas must be
undertaken before assuming that the primary is occult. Primary tumors
arising in the nasopharynx may be secondary to Epstein-Barr Virus
(EBV) infection, and EBV genomic material may be detectable in cervical nodal
tissue after DNA amplification using the polymerase chain reaction. Such a
finding should lead to an in-depth search for a primary in the nasopharynx.[1]
The extent of investigation and type of treatment must be individualized
depending on the patient's age and wishes, and on the site, histology, and extent of metastatic lymph
node involvement of the tumor. When a patient qualifies as
having squamous carcinoma of the neck with occult primary, he or she should be checked for other
obvious metastatic disease, such as lung, liver, or bone, since this would
affect the locoregional approach to therapy.[2]
Three-year disease-free survival rates following surgery and/or radiation
therapy for unknown squamous primaries range from 40% to 50% in patients with N1 disease to 38%
and 26% for patients with N2 and N3 disease, respectively. Patients who later develop
primary lesions have poor survival rates compared to those patients whose
primaries remain occult, for example 30% versus 60%.
Patients with neck metastases from an undetectable primary should be given the benefit of definitive treatment. Despite the ominous
situation of an undiscovered primary, a significant number of patients do
achieve cure by both surgical and radiotherapeutic approaches. In some
patients, long-term repeat examinations will eventually disclose the primary
tumor, and at a treatable stage.
References
-
Feinmesser R, Miyazaki I, Cheung R, et al.: Diagnosis of nasopharyngeal carcinoma by DNA amplification of tissue obtained by fine-needle aspiration. N Engl J Med 326 (1): 17-21, 1992.
[PUBMED Abstract]
-
de Braud F, al-Sarraf M: Diagnosis and management of squamous cell carcinoma of unknown primary tumor site of the neck. Semin Oncol 20 (3): 273-8, 1993.
[PUBMED Abstract]
Back to Top
< Previous Section | Next Section > |