Histological grade is the most important factor for defining treatment strategies and predicting prognosis for salivary gland carcinoma (SGC). Although several studies have addressed low- and high-grade SGCs, intermediate-grade SGC (IGSGC) has received minimal attention. Therefore, we examined factors affecting long-term recurrence and survival among IGSGC patients to define optimal treatment modalities and outcomes.
We reviewed the clinical and pathological data of 108 IGSGC patients who underwent definitive surgery with or without postoperative radiotherapy at our tertiary referral center between 1994 and 2014. We performed univariate and multivariate analyses of variables predictive of locoregional control (LRC), distant metastasis-free survival (DMFS), and overall survival (OS). We compared treatment outcomes by treatment strategies such as surgical extent, primary tumor, neck dissection, or postoperative radiotherapy.
During a median 103 (range, 24–282)-month follow-up, local, regional, and distant recurrences were detected in 14 (13.0%), 3 (2.8%), and 21 (19.4%) patients, respectively. The 10-year LRC, DMFS, and OS rates were 83.1%, 76.0%, and 80.1%, respectively. Multivariate analyses identified a non-parotid primary site as an independent prognostic factor for LRC (P = 0.018), Adenoid cystic carcinoma and positive pN classification were significantly unfavorable prognostic factors for DMFS (P = 0.025 and P = 0.030, respectively); overall advanced stage was an independent prognostic factor for OS (P = 0.020). Surgical extent, elective neck dissection, and postoperative adjuvant radiotherapy did not significantly affect treatment outcomes.
Patients with early-stage IGSGC of parotid origin can achieve favorable treatment outcomes with conservative surgery alone.
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All authors have declared no conflicts of interest.