Low-Grade Salivary Gland Cancers: Treatment Outcomes, Extent of Surgery and Indications for Postoperative Adjuvant Radiation Therapy

• Published in: Annals of surgical oncology Vol. 23; no. 13; pp. 4368 - 4375
• Main Authors: Cho, Jae-Keun, Lim, Byung-Woo, Kim, Eun-Hye, Ko, Young-Hyeh, Oh, Dongryul, Noh, Jae-Myoung, Ahn, Yong Chan, Baek, Kwan-Hyuck, Jeong, Han-Sin
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.12.2016; Springer Nature B.V
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Child; Disease-Free Survival; Female; Head and Neck Oncology; Humans; Lymphatic Metastasis; Male; Margins of Excision; Medicine; Medicine & Public Health; Middle Aged; Neoplasm Grading; Neoplasm Invasiveness; Neoplasm Recurrence, Local - pathology; Neoplasm Staging; Neoplasm, Residual; Oncology; Radiotherapy, Adjuvant; Retrospective Studies; Risk Factors; Salivary Gland Neoplasms - pathology; Salivary Gland Neoplasms - surgery; Salivary Gland Neoplasms - therapy; Surgery; Surgical Oncology; Survival Rate; Treatment Outcome; Young Adult; Adenoid Cystic Carcinoma; Postoperative Radiation Therapy; Pleomorphic Adenoma; Lymphovascular Invasion; Neck Dissection
• ISSN: 1068-9265; 1534-4681
• DOI: 10.1245/s10434-016-5353-6

Background Histologic grade of tumor is one of the major prognostic predictors for patients with salivary gland cancer. Because of disease rarity, little is known about the optimal treatment modalities and outcomes in low-grade salivary gland cancers (LGSGC). We tried to identify prognostic factors, and the adequate treatment modalities and outcomes in pathologically confirmed LGSGC patients. Methods We retrospectively extracted the clinical and pathology data from 179 LGSGC cases from 1995 to 2013. Pathological features, such as extraparenchymal extension, perineural/nerve invasion, lymphovascular invasion/tumor emboli, and resection margin status were redefined for each case. Risk factors for recurrence, extent of surgery, and the role of postoperative radiation therapy were analyzed. Results Recurrence-free survival and overall survival were 89.6 and 96.6 % at 10 years, respectively. The presence of regional nodal metastasis and positive cancer cells at resection margin were significant unfavorable prognostic factors. Postoperative adjuvant radiation treatment significantly reduced recurrences, particularly in cases with pathology risk factors (perineural invasion, lymphovascular invasion, extraparenchymal extension, or cancer cells at the resection margin), node metastasis, and advanced T-stage tumors. Close surgical margin <5 mm was not a significant risk factor for recurrence, and less-than-total resection of the affected gland did not increase recurrence, if surgery could achieve a cancer cell-free surgical margin. Conclusion Postoperative radiation clearly benefitted patients with pathology risk factors, node metastasis, and advanced T stage in LGSGC. Meanwhile, the oncological outcomes are very good with surgery alone in cases of pT1-2N0 LGSGC without pathology risk factors.