DISTANT METASTASIS IN ADENOID CYSTIC CARCINOMA OF SALIVARY ORIGIN

BACKGROUND: Adenoid cystic carcinoma (ACC) is an aggressive, often ind olent tumor, with a high incidence of distant metastasis (DM). Relativ ely little has been written about the factors that influence distant s pread and subsequent survival because it is uncommon and more than a d ecade of observation may be required to appreciate the prolonged clini cal course in some patients. METHODS: We have retrospectively studied 196 determinate patients who received definitive treatment in our hosp ital between 1939 and 1986 for ACC in all salivary sites. Inclusion cr iteria were no prior treatment elsewhere other than excisional biopsy and eligibility for follow-up of at least 10 years. Variables assessed for their impact on distant metastasis included age, gender, site, si ze, node status, stage, grade, and locoregional treatment failure. RES ULTS: Treatment failure occurred in a total of 122 of 196 determinate patients (62%), 74 of whom had DM (38%). This was usually associated w ith locoregional recurrence (51 patients), but DM was the only indicat ion of failure in 23 whose primary tumor was controlled. Of the 74 pat ients with known DM, the lung was recorded as the only involved site i n 50 patients, lung was involved in addition to other sites in 17, bon e metastases alone occured in 5, and the remaining 2 developed dissemi nated disease. Disease-free intervals varied from 1 month to 19 years (median 36 months) and exceeded 10 years in 9 of 113 patients (8%) wit h adequate information about treatment failure. Survival with DM was l ess than 3 years in 54%, but more than 10 yrs in 10% (maximum 16 years ). The only significant factors influencing survival were the size of the primary tumor (P <0.0000), local or neck recurrence (P = 0.0006), and the presence of nodal involvement (P = 0.02). CONCLUSIONS: The hig h incidence of DM with locoregional failure confirms the importance of aggressive initial surgery, combined with irradiation, for high-stage tumors or involved surgical margins. Large tumor size and lymph node involvement, rather than microscopic appearance, were predictive of DM . Considering that lung metastases are usually multiple, and prolonged survival without treatment is not unusual, resection of pulmonary met astases may be hard to justify in ACC patients based on the limited ex perience thus far reported. Chemotherapy for metastatic ACC is probabl y best withheld until symptoms appear. (C) 1997 by Excerpta Medica, In c.