Analysis of salivary duct carcinoma at 13 facilities in northern Japan

We performed a retrospective analysis of 157 cases of salivary duct carcinoma treated at 13 institutions in northern Japan. Median age was 68 years, male to female ratio was 4：1, parotid gland primary was 71％, T ≥ 3 was 62％, N1-3 was 59％, M1 was 13％, and clinical stage ≥ Ⅳ was 66％. For all patients, 3y-overall survival (OS)was 69.9％(95％CI 61.3-78.5)and 5y-OS was 56.4％(95％CI 46.1-66.7). The 3y disease-free survival (DFS)was 37.1％(95％CI 29.1-45.2)and the 5y-DFS was 30.6％(95％CI 22.1-39.0). Among the 100 cases with recurrence or residual disease, distant metastasis was most commonly observed. For cases undergoing curative surgery, the statistically significant poor prognostic factors were positive resection margin for OS, and neck metastasis and primary site other than the parotid gland for DFS. In addition, postoperative radiotherapy was effective in the positive resection margin group and neck metastasis group. On the other hand, elective neck dissection for N0 cases was not effective in any group.