Adenoid cystic salivary gland carcinoma. A histopathologic review of treatment failure patterns.

Seventy-one cases of adenoid cystic salivary gland carcinoma were reviewed according to treatment modality and clinical course. Thirty-six patients (51%) were treated by combined surgery and radiation therapy. The tumors were classified by their histologic patterns into tubular, cribriform, and solid forms. Distant metastases, in 52%, were the most frequent and ominous sources of failure. In 35% of cases, distant metastases developed despite local control at the primary site. In this group, the disease had a more fulminant course with shorter survival. Histopathologically, the cribriform subtype was associated with multiple local recurrences, greater local aggressiveness, and a poorer salvage rate as compared with the tubular subtype. Late onset of local recurrences and distant metastases was especially associated with the cribriform subtype. Overall prognosis in terms of distant metastases and survival was worst for the solid subtype. Control of local disease is best achieved with combined surgery and radiation therapy. The high incidence of distant metastases may not be affected by this regimen. The ultimate outcome of therapy is poorly predicted. Survival appears to be based on the pattern in which distant metastases develop. Overly aggressive and mutilating surgical approaches for these tumors are not recommended in many instances. The need for the development of new, more effective forms of therapy is emphasized.