Salivary Gland Malignancies: Diagnosis and Treatment of a Rare and Challenging Cancer

There is some controversy regarding the indications for FNA in the evaluation of parotid masses. Dr. Schaitkin cautioned that FNA is not 100% accurate. He recalled one 25-year-old female patient, for instance, whose aspiration biopsy was negative for malignancy, and yet he eventually removed her tumor, which turned out to be cancerous.

False positives and false negatives are not uncommon, especially when FNA is used to evaluate parotid masses. David W. Eisele, MD, is Director of the Head and Neck Cancer Program at the UCSF Helen Diller Family Comprehensive Cancer Center and Professor and Chairman of the Department of Otolaryngology-Head and Neck Surgery at the University of California, San Francisco. He and colleagues at Johns Hopkins published a review article in Current Opinion in Otolaryngology and Head and Neck Surgery in 2006 about the accuracy of fine-needle aspiration biopsy. Despite reported accuracy rates of 90% to 95%, some parotid neoplasms are prone to diagnostic error. For instance, ACC may frequently be interpreted as benign. Whether one uses the fine needle aspiration routinely or selectively in patients with parotid masses, the fine needle aspiration findings should contribute to, not displace, the overall diagnostic impression, the authors wrote.6

Fine-needle aspiration biopsy is very dependent on the expertise of your cytopathologist, asserted Dr. Schaitkin. Most people believe their needle-and this can lead to some errors in treatment. [Results of a fine-needle aspiration biopsy] are not always correct. It’s just one piece of data.

Dr. Medina emphasized that there is no substitute for a thorough preoperative evaluation, to include history, physical, and a CT or MRI scan. The 2008 National Comprehensive Cancer Network (NCCN) Practice Guidelines for Head and Neck Cancers recommend a full history and phy sical, either a CT or MRI, pathology review, chest imaging, and either FNA or open biopsy.7 A well-thought-out open biopsy is valuable, according to Dr. Medina, in selected cases where characteristics of the mass are such that an inflammatory process of metastases from elsewhere must be ruled out and the FNA is repeatedly inconclusive.

Challenges for Surgeons

Treatment for salivary gland malignancies remains primarily surgical. Adjuvant radiation is recommended to help reduce risk of locoregional recurrence if there is lymph node metastasis, a high-grade tumor, positive margins, and T3-4 stage disease.8 Definitive radiation therapy has also been used as primary treatment for salivary gland malignancies that are deemed inoperable. Dr. Eisele and colleagues from the Department of Radiation Oncology at UCSF’s Comprehensive Cancer Center found that radiation alone was effective treatment in very select patients. In their retrospective series of 45 patients treated at their center, T3-4 disease and receiving radiation doses lower than 66 Gy were independent predictors of local recurrence.9