Background: The purpose of the current study was to determine the incidence of late recurrences, which were defined as those occurring >or=5 years after initial therapy, among patients treated for salivary gland cancer.
Methods: Between 1960 and 2000, 145 patients underwent definitive therapy for localized carcinomas of the salivary glands and were clinically without evidence of disease at 5 years of follow-up. Cumulative probabilities for developing a subsequent late recurrence were estimated using the Kaplan-Meier method.
Results: The 10-year and 15-year cumulative probabilities of late recurrence in patients who were free of disease at 5 years were 13% and 18%, respectively. The crude rates of late recurrence by histologic subtype were adenoid cystic carcinoma (26%), mixed malignant tumor (25%), mucoepidermoid carcinoma (17%), adenocarcinoma (10%), and acinic cell carcinoma (8%). Sites of late recurrence included distant metastasis (17 patients), local recurrence (8 patients), and regional recurrence (2 patients). The median time to late recurrence was 7.1 years (range, 5.2-23.1 years) from the date of initial surgery. Salvage treatment varied according to location of disease recurrence and initial treatment characteristics. The 15-year estimate of overall survival was 39% for patients who experienced a late recurrence compared with 71% for those who remained free of disease (P= .001).
Conclusions: A significant proportion of patients who are presumed to be cured of their disease at 5 years after initial treatment for salivary gland cancer will be found to develop late disease recurrence with additional follow-up.