Prognostic analysis and establishment of a nomogram in patients with myoepithelial carcinoma of the salivary gland: A population‐based study

BACKGROUND: Currently, the clinicopathological characteristics and prognosis of myoepithelial carcinoma of salivary gland (MC‐SG) have not been defined well. The present study aimed to describe the clinicopathological characteristics and prognosis of MC‐SG patients. METHODS: The Surveillance, Epidemiology, and End Results database was searched for all patients diagnosed with MC‐SG between 1991 and 2016. The Kaplan–Meier method and log‐rank tests were used to evaluate the survival. Univariate and multivariate Cox regression analysis were used to identify prognostic biomarkers for overall survival (OS) and disease‐specific survival (DSS). Furthermore, a prognostic nomogram was established, and its predictive accuracy and discriminative ability were determined using the concordance index (C‐index). RESULTS: In total, 245 patients diagnosed with MC‐SG were identified. The median OS was 152.0 months, with 3‐, 5‐, and 10‐year survival rates of 79.8%, 69.2%, and 50.3%. The 3‐, 5‐, and 10‐year DSS rates were 82.5%, 77.1%, and 61.9%, respectively. Regarding the treatment regimen, most patients (92.2%) underwent surgery, and 103 patients (42.4%) received postoperative radiotherapy. Surgery could significantly prolong OS and DSS (p < .05), but postoperative radiotherapy did not significantly prolong OS and DSS when compared with individuals receiving surgery alone (p > .05). Multivariate Cox analysis revealed that T category (T4), lymph node metastasis (N2), distant metastasis (M1), and poor differentiation were independent unfavorable prognostic factors for OS and DSS. Older age (>62 years) was also independently associated with OS. In addition, the C‐index for the established OS‐ and DSS‐specific nomogram was 0.80 (95% CI: 0.72–0.88) and 0.82 (95% CI: 0.73–0.90). CONCLUSION: Age, tumor invasion, metastases, and pathological grade were independently associated with prognosis of MC‐SG patients, and the prognostic nomogram of this rare disease was established.