Survival in patients with submandibular gland carcinoma — Results of a multi-institutional retrospective study
Introduction
Salivary glands comprise the parotid, submandibular, sublingual, and minor glands. The 2005 World Health Organization classification included 24 malignant salivary gland tumors with many subtypes [dataset] [1]. Submandibular gland carcinoma is relatively rare; 7–11% of all primary epithelial salivary gland tumors occur in the submandibular glands, and 41–45% of submandibular gland tumors are malignant [dataset] [1]. Because of the rarity of the tumors, the literature is consequently limited and the information provided to patients is not sufficient. A better understanding of the tumor, including the patient, tumor, and treatment characteristics remains to be established. Although several studies [dataset] [2], [3], [4], [5], [6], [7], [8] have been conducted to reveal the clinical outcomes and prognostic factors of submandibular gland carcinoma, there are only a few reports [dataset] [2], [3], [4], [5], [6] so far that involve more than 50 patients. A multi-institutional study enables us to analyze a relatively large number of patients. The aim of this retrospective study was to update the clinical outcomes and prognostic factors of submandibular gland carcinoma, based on data from multiple centers.
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Patients and methods
This study involved 65 patients with previously untreated submandibular gland carcinoma who underwent curative surgery at the Kyoto University and its affiliated hospitals between 2006 and 2015. These included 12 medical centers in Japan: the Kyoto University Graduate School of Medicine, Japanese Red Cross Wakayama Medical Center, Kurashiki Central Hospital, Japanese Red Cross Osaka Hospital, Kobe City Medical Center General Hospital, Kitano Hospital, Tenri Hospital, Shizuoka General Hospital,
Patient characteristics
A total of 77 cases of surgically treated submandibular gland carcinoma were identified. Twelve cases (16%) that presented with distant metastasis at the initial surgery were excluded from the analysis. After exclusion, 65 cases remained for analysis.
Patient, tumor, and treatment characteristics are summarized in Table 1. The mean age was 63.1 years (range, 33–87). A total of 58% of tumors were classified as high-grade malignancy. Table 2 shows the distribution of tumor histology and grade. The
Discussion
Submandibular gland carcinoma is a rare entity, and the literature is limited. The present study has provided a systematic evaluation of the clinical characteristics and treatment outcomes of the tumor.
As the 2005 World Health Organization classification includes 24 malignant salivary gland tumors with several subtypes, there are many histological types [dataset] [1]. In this study, the most frequent histology was adenoid cystic carcinoma, followed by carcinoma ex pleomorphic adenoma, salivary
Conclusion
In summary, we performed a retrospective study based on multi-institutional data to show the prognostic factors of submandibular gland carcinoma. This study suggested death that from the disease occurred mainly due to distant metastasis. The following were significant factors: lymph node metastases (≥N2) were related to OS, LRC, and NDM, and tumor grade (high grade) was related to NDM.
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