Diagnosis and staging
Types of tests
Panendoscopy and biopsy – patients undergo open endoscopy, not only to evaluate the extent of the tumor and confirm the histology, but also to exclude the occurrence of additional primary lesions.
Radiographs – a chest X-ray is useful as an initial screening test for metastatic lung disease or a second primary lung tumor. In addition, modern imaging techniques, including CT scans and MRI scans, are used as an aid in staging head and neck tumors and planning treatment.
Liver function tests – liver function tests or blood tests are used as the screening evaluation for liver metastasis; although, if liver lesions are suspected, much more accurate testing (CT scans or liver spleen scans) may be employed.
Bone scans – used when clinically indicated by the presence of skeletal pain or pathologic fractures.
PET scan – positron emission tomography is increasingly being used in patients with identifiable neck metastases to search for an unknown primary tumor, or to evaluate for recurrent tumors in individuals that are difficult to assess due to previous therapy. It also has a role in defining distant metastases. The recent addition of combined PET/CT scanning has further improved accuracy.
Histology (microscopic cellular appearance)
Ciliated pseudostratified columnar epithelium lines the respiratory tract with the exception of the vocal cords, which are covered by nonkeratinizing squamous epithelium. The remainder of the upper aurodigestive tract, including the pharynx, also is covered by the nonkeratinizing squamous epithelium. Premalignant lesions demonstrate hyperkeratosis, hyperplasia and dysplasia. The terms leukoplakia and erythroplakia are descriptions meaning white plaque and red plaque respectively and not histologic diagnoses. Moreover, 10 percent of leukoplastic lesions are noted to contain malignant cells as opposed to 30 percent of erythroplastic lesions. The majority of head and neck cancers arise from this squamous epithelium and are called squamous cell carcinoma.
Parameters of prognosis
Tumor stage is of primary importance in determining treatment options and the prognosis of head and neck carcinoma. It is important to note that once regional lymph node involvement occurs, the survival rate drops by 50 percent. The TNM system is used.
T = tumor size
N = status of the neck lymph nodes
M = presence or absence of distant metastatic disease
Tumor differentiation, while useful, is not as important a prognostic factor, as seen with squamous cell carcinoma.
Tumor host interactions may be important in the prognosis of head and neck cancer. The manner and extent to which the immune system responds to cancer is of interest. Studies including those examining tumor associated tissue eosinophilia have demonstrated some fascinating results.
The more eosinophilic infiltration of the tumor, the better the prognosis. Presumably, this factor indicates a greater host response to the tumor.
On the other hand, diffuse inflammatory and fibrous tissue infiltration at the tumor site known as desmoplastic reaction is thought to indicate a worse prognosis.
Perineural invasion at the tumor site has been associated with more extensive local and regional disease and, therefore, a worse prognosis.
Vascular invasion is an important step in the development of metastasis. Although most circulating tumor cells do not develop into metastasis, the greater the number released into the vascular system, the higher the likelihood.