Late recurrence from salivary gland cancer: When does "cure" mean cure?

BACKGROUND. The purpose of the current study was to determine the incidence of late recurrences, which were defined as those occurring ≥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.