Incidence and risk factors of late recurrence in patients with salivary gland cancer.

OBJECTIVES: Recurrence in the late post-treatment period is relatively common in salivary gland cancer (SGC), but risk factors and survival associated with late recurrence have been rarely studied. We investigated the incidence and risk factors of SGC recurrence >5 years after treatment and associated survival.

DESIGN: A retrospective cohort study.

SETTING: University hospital.

PARTICIPANTS: A total of 240 patients with previously untreated SGC who underwent definitive treatment.

MAIN OUTCOME MEASURES: Late recurrence was defined as recurrence at a time point >5 years after treatment. Univariate and multivariable analyses were used to identify the association of clinicopathologic factors with recurrence-free survival (RFS), cancer-specific survival (CSS) and late recurrence.

RESULTS: Of the 240 patients, 124 (51.7%) patients developed recurrence during a median follow-up of 160.0 months (range 121.5-282.2 months). Sixteen (6.7%) patients developed late recurrence; the median time to late recurrence was 92.5 months (range 60.2-138.3 months) after treatment. Multivariable analysis showed that primary site, histologic grade and N classification were independent variables of both RFS and CSS (P < 0.05 each). Extraparenchymal extension was also an independent variable of CSS (P = 0.022). In addition, a non-parotid tumour location was a significant factor for late recurrence in multivariable analysis (P = 0.017). The median overall survival after the development of late recurrence was 79.7 months (range 0.2-163.4 months), significantly longer than that after early recurrence (19.7 months) (P = 0.043).

CONCLUSION: Late recurrence occurs in some SGC patients. Long-term close surveillance may be required for patients with non-parotid SGC.