Prognostic factors in postoperative radiotherapy in salivary gland carcinoma: A single institution experience from Turkey

Background: We reviewed clinical characteristics, treatment outcomes, local and distant failure and prognostic factors in patients with salivary gland carcinoma treated with surgery and postoperative radiotherapy. Materials and Methods: We retrospectively reviewed 75 patients with salivary gland cancer. 69 (%92) patients had cancer of the parotid gland, 3 (%4) patients had cancer of the submandibular gland and 3 (%4) patients had cancer of the minor salivary gland. 4 patients underwent postoperative chemoradiotherapy and 71 patients underwent postoperative radiotherapy. Median radiotherapy dose was 60Gy (range, 30Gy to 69Gy). Results: Median age was 59.6±17.9 (13-88) and the female/male ratio was 1/1.7. Median follow-up 52 months (2-228 months). The mean overall survival 69.2±8 (95%confidence interval[CI], 53.4-85.1) months. The 1-,3-,5- and 10- year overall survival rates were 79.8%, 53.2%, 37.4% and 22.8% respectively. The mean disease free survival 79.7±10 (95%CI, 60.1-99.3) months. The 1-,3-,5- and 10- year disaese free survival rates were 72.8%, 51.9%, 44.1% and 30.4% respectively. On multivariate analysis, the OS was significantly better for the female sex (hazard ratio[HR]:3,0;95%CI:1.5-5.6; P =0.001), absence of lymph node involvement ([HR]:3,0;95%CI:1.7-5.3; P =0.0001), lower tumor grade ([HR]:25,7;95%CI:3.3-199.3; P =0.002), negativity of the surgical margin ([HR]:2,3;95%CI:1.3-4.2; P =0.005), absence of lymphovasculer invasion ([HR]:2,6;95%CI:1.5-4.6; P =0.001), absence of extracapsuler extension ([HR]:6,5;95%CI:2.2-19.1; P =0.001), absence of perineural invasion ([HR]:4,8;95%CI:2.6-8.7; P =0.0001) and ≤60Gy radiotherapy dose ([HR]:3,1;95%CI:1.7-5.5; P =0.0001). They observed local recurrens in17 (23%) patients and distant metastasis in 33 (44%) patients. Conclusions: Employing existing standards of postoperative radiotherapy is a possible treatment that was found to be effective mainly in patients with salivary gland carcinomas.