Supplementary Material for: Survival Outcome of Intermediate-Grade Salivary Gland Carcinoma

Objective: Histological grade is the most important
factor for defining treatment strategies and predicting prognosis for
salivary gland carcinoma (SGC). We examined factors affecting long-term
recurrence and survival among intermediate-grade SGC (IGSGC) patients to
define optimal treatment modalities and outcomes. Methods:
We reviewed the clinical and pathological data on 108 IGSGC patients
who underwent definitive surgery with or without postoperative
radiotherapy. We compared treatment outcomes by treatment strategies
such as surgical extent for the primary tumor, neck dissection, or
postoperative radiotherapy. Results: During a 103-month
median 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 locoregional control (LRC), distant metastasis-free survival
(DMFS), and overall survival (OS) rates were 83.1, 76.0, and 80.1%,
respectively. Multivariate analyses identified a nonparotid primary site
as an independent prognostic factor for LRC (p = 0.018). Adenoid
cystic carcinoma and a 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. Conclusion: Patients with early-stage IGSGC of parotid origin can achieve favorable treatment outcomes with conservative surgery alone.