title: Low-Grade Salivary Gland Cancers: Treatment Outcomes, Extent of Surgery and Indications for Postoperative Adjuvant Radiation Therapy.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Inje University Ilsan Paik Hospital, Inje University School of Medicine, Goyang, Republic of Korea.
authors.forename: Jae-Keun
authors.initials: JK
authors.lastname: Cho
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Inje University Ilsan Paik Hospital, Inje University School of Medicine, Goyang, Republic of Korea.
authors.forename: Byung-Woo
authors.initials: BW
authors.lastname: Lim
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Eun-Hye
authors.initials: EH
authors.lastname: Kim
authors.affiliation: Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Young-Hyeh
authors.initials: YH
authors.lastname: Ko
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Dongryul
authors.initials: D
authors.lastname: Oh
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Jae-Myoung
authors.initials: JM
authors.lastname: Noh
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Yong Chan
authors.initials: YC
authors.lastname: Ahn
authors.affiliation: Department of Molecular and Cellular Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Gyeonggi, Republic of Korea. khbaek@skku.edu.
authors.forename: Kwan-Hyuck
authors.initials: KH
authors.lastname: Baek
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. hansin.jeong@gmail.com.
authors.forename: Han-Sin
authors.initials: HS
authors.lastname: Jeong
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D000072662:Margins of Excision; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000473:pathology*; D009367:Neoplasm Staging; D018365:Neoplasm, Residual; D018714:Radiotherapy, Adjuvant; D012189:Retrospective Studies; D012307:Risk Factors; D012468:Salivary Gland Neoplasms / Q000473:pathology* / Q000601:surgery / Q000628:therapy*; D015996:Survival Rate; D016896:Treatment Outcome; D055815:Young Adult