Salivary Gland Tumors
Incidence
Salivary gland tumors are rare and account for 0.5% of all malignancies in children and adolescents. After rhabdomyosarcoma, they are the most common tumor in the head and neck.[1,2] Salivary gland tumors may occur after radiation therapy and chemotherapy are given for the treatment of primary leukemia or solid tumors.[3,4]
Clinical Presentation
Most salivary gland neoplasms arise in the parotid gland.[5,6,7,8,9,10] About 15% of these tumors arise in the submandibular glands or in the minor salivary glands under the tongue and jaw.[8] These tumors are most frequently benign but may be malignant, especially in young children.[11]
Histology and Molecular Features
The most common malignant salivary gland tumor in children is mucoepidermoid carcinoma, followed by acinic cell carcinoma and adenoid cystic carcinoma. Less common malignancies include rhabdomyosarcoma, adenocarcinoma, and undifferentiated carcinoma.[1,8,10,12,13,14] Mucoepidermoid carcinoma is usually low or intermediate grade, although high-grade tumors do occur. Mammary analogue secretory carcinoma (MASC) of the salivary gland is a newly described pathological entity that has been seen in children.[15][Level of evidence C1] In one review, it was estimated that 12% of MASC cases occurred in the pediatric population.[16,17]
In a series of pediatric patients with salivary gland tumors, immunohistochemical and molecular profiling showed similarities to those tumors observed in adults.[18] In one study, 12 of 12 tumors were positive for CRTC1::MAML2 fusion transcripts. This reflects the common chromosome translocation t(11;19)(q21;p13) that is seen in adults with salivary gland tumors.[19] MASC is characterized by an ETV6::NTRK3 fusion.[20]
Prognosis
The 5-year overall survival (OS) rate for salivary gland tumors in the pediatric age group is approximately 95%.[21] A review of the Surveillance, Epidemiology, and End Results Program database identified 284 patients younger than 20 years with tumors of the parotid gland.[22][Level of evidence C1] The OS rate was 96% at 5 years, 95% at 10 years, and 83% at 20 years. Adolescents had higher mortality rates (7.1%) than children younger than 15 years (1.6%; P = .23).
A retrospective, multi-institutional survey identified 103 patients younger than 18 years with parotid gland cancer; mucoepidermoid carcinoma was the most common histology (71 patients).[23][Level of evidence C1] The authors did not report if patients underwent previous therapies; however, they mentioned that 12 of 103 patients had a history of lymphoma. The 10-year relapse-free survival (RFS) rate for the entire group was 91%. Presence of intraparotid lymph node metastasis (LNM) was associated with significantly worse event-free survival and OS, as was history of previous therapy for lymphoma. The 10-year RFS rate was 91% for patients without intraparotid LNM and 37% for patients with intraparotid LNM.
Mucoepidermoid carcinoma is the most common type of treatment-related salivary gland tumor. With standard therapy, the 5-year survival rate is about 95% for patients with this tumor.[14,24,25]
A retrospective review identified 57 pediatric patients (aged <18 years) (4.6%) and 1,192 adult patients (95.4%) with acinic cell carcinoma.[26] Clinical LNMs were rare in children (n < 10) and adults (n = 88; 7.4%). Occult LNMs were uncommon in pediatric patients (n < 5) and adult patients (n = 41; 4.6%). The 3-year OS rate was 97.8% for pediatric patients. Adult patients with LNMs had worse 3-year OS rates than those without LNMs (66.0% vs. 96.3%; P < .001).
Treatment of Childhood Salivary Gland Tumors
The European Cooperative Study Group for Pediatric Rare Tumors within the PARTNER project (Paediatric Rare Tumours Network - European Registry) has published consensus guidelines for the diagnosis and treatment of childhood salivary gland tumors.[27]
Treatment options for childhood salivary gland tumors include the following:
- Surgery.
- Radiation therapy.
- Targeted therapy.
Surgery
Radical surgical removal is the treatment of choice for salivary gland tumors whenever possible, with additional use of radiation therapy for high-grade tumors or tumors that have invasive characteristics such as LNM, positive surgical margins, extracapsular extension, or perineural extension.[21,28,29]; [9][Level of evidence C1] Parotid gland tumors are removed with the aid of neurological monitoring to prevent damage to the facial nerve.
Radiation therapy
One retrospective study compared proton therapy with conventional radiation therapy and found that proton therapy had a favorable acute toxicity and dosimetric profile.[30] Another retrospective study used brachytherapy with iodine I 125 seeds to treat 24 children with mucoepidermoid carcinoma who had high-risk factors. Seeds were implanted within 4 weeks of surgical resection. With a median follow-up of 7.2 years, the disease-free survival and OS rates were 100%; no severe radiation-associated complications were reported.[31][Level of evidence C2]
Targeted therapy
Objective responses have been observed in all reported patients with recurrent NTRK fusion–positive MASC who were treated with entrectinib or larotrectinib.[32,33] Ten of 11 adolescent or adult patients with TRK fusion–positive salivary gland tumors who were treated with larotrectinib experienced partial or complete responses.[33]
For more information, see Salivary Gland Cancer Treatment.
Treatment Options Under Clinical Evaluation for Childhood Salivary Gland Tumors
Information about National Cancer Institute (NCI)–supported clinical trials can be found on the NCI website. For information about clinical trials sponsored by other organizations, see the ClinicalTrials.gov website.
References:
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- Cesmebasi A, Gabriel A, Niku D, et al.: Pediatric head and neck tumors: an intra-demographic analysis using the SEER* database. Med Sci Monit 20: 2536-42, 2014.
- Chowdhry AK, McHugh C, Fung C, et al.: Second primary head and neck cancer after Hodgkin lymphoma: a population-based study of 44,879 survivors of Hodgkin lymphoma. Cancer 121 (9): 1436-45, 2015.
- Boukheris H, Stovall M, Gilbert ES, et al.: Risk of salivary gland cancer after childhood cancer: a report from the Childhood Cancer Survivor Study. Int J Radiat Oncol Biol Phys 85 (3): 776-83, 2013.
- da Cruz Perez DE, Pires FR, Alves FA, et al.: Salivary gland tumors in children and adolescents: a clinicopathologic and immunohistochemical study of fifty-three cases. Int J Pediatr Otorhinolaryngol 68 (7): 895-902, 2004.
- Muenscher A, Diegel T, Jaehne M, et al.: Benign and malignant salivary gland diseases in children A retrospective study of 549 cases from the Salivary Gland Registry, Hamburg. Auris Nasus Larynx 36 (3): 326-31, 2009.
- Fu H, Wang J, Wang L, et al.: Pleomorphic adenoma of the salivary glands in children and adolescents. J Pediatr Surg 47 (4): 715-9, 2012.
- Galer C, Santillan AA, Chelius D, et al.: Minor salivary gland malignancies in the pediatric population. Head Neck 34 (11): 1648-51, 2012.
- Thariat J, Vedrine PO, Temam S, et al.: The role of radiation therapy in pediatric mucoepidermoid carcinomas of the salivary glands. J Pediatr 162 (4): 839-43, 2013.
- Chiaravalli S, Guzzo M, Bisogno G, et al.: Salivary gland carcinomas in children and adolescents: the Italian TREP project experience. Pediatr Blood Cancer 61 (11): 1961-8, 2014.
- Laikui L, Hongwei L, Hongbing J, et al.: Epithelial salivary gland tumors of children and adolescents in west China population: a clinicopathologic study of 79 cases. J Oral Pathol Med 37 (4): 201-5, 2008.
- Rahbar R, Grimmer JF, Vargas SO, et al.: Mucoepidermoid carcinoma of the parotid gland in children: A 10-year experience. Arch Otolaryngol Head Neck Surg 132 (4): 375-80, 2006.
- Kupferman ME, de la Garza GO, Santillan AA, et al.: Outcomes of pediatric patients with malignancies of the major salivary glands. Ann Surg Oncol 17 (12): 3301-7, 2010.
- Aro K, Leivo I, Mäkitie A: Management of salivary gland malignancies in the pediatric population. Curr Opin Otolaryngol Head Neck Surg 22 (2): 116-20, 2014.
- Simon CT, McHugh JB, Rabah R, et al.: Secretory Carcinoma in Children and Young Adults: A Case Series. Pediatr Dev Pathol 25 (2): 155-161, 2022 Mar-Apr.
- Ngouajio AL, Drejet SM, Phillips DR, et al.: A systematic review including an additional pediatric case report: Pediatric cases of mammary analogue secretory carcinoma. Int J Pediatr Otorhinolaryngol 100: 187-193, 2017.
- Khalele BA: Systematic review of mammary analog secretory carcinoma of salivary glands at 7 years after description. Head Neck 39 (6): 1243-1248, 2017.
- Locati LD, Collini P, Imbimbo M, et al.: Immunohistochemical and molecular profile of salivary gland cancer in children. Pediatr Blood Cancer 64 (9): , 2017.
- Techavichit P, Hicks MJ, López-Terrada DH, et al.: Mucoepidermoid Carcinoma in Children: A Single Institutional Experience. Pediatr Blood Cancer 63 (1): 27-31, 2016.
- Skálová A, Vanecek T, Sima R, et al.: Mammary analogue secretory carcinoma of salivary glands, containing the ETV6-NTRK3 fusion gene: a hitherto undescribed salivary gland tumor entity. Am J Surg Pathol 34 (5): 599-608, 2010.
- Rutt AL, Hawkshaw MJ, Lurie D, et al.: Salivary gland cancer in patients younger than 30 years. Ear Nose Throat J 90 (4): 174-84, 2011.
- Allan BJ, Tashiro J, Diaz S, et al.: Malignant tumors of the parotid gland in children: incidence and outcomes. J Craniofac Surg 24 (5): 1660-4, 2013.
- Seng D, Fang Q, Liu F, et al.: Intraparotid Lymph Node Metastasis Decreases Survival in Pediatric Patients With Parotid Cancer. J Oral Maxillofac Surg 78 (5): 852.e1-852.e6, 2020.
- Verma J, Teh BS, Paulino AC: Characteristics and outcome of radiation and chemotherapy-related mucoepidermoid carcinoma of the salivary glands. Pediatr Blood Cancer 57 (7): 1137-41, 2011.
- Védrine PO, Coffinet L, Temam S, et al.: Mucoepidermoid carcinoma of salivary glands in the pediatric age group: 18 clinical cases, including 11 second malignant neoplasms. Head Neck 28 (9): 827-33, 2006.
- Dublin JC, Oliver JR, Tam MM, et al.: Nodal Metastases in Pediatric and Adult Acinic Cell Carcinoma of the Major Salivary Glands. Otolaryngol Head Neck Surg 167 (6): 941-951, 2022.
- Surun A, Schneider DT, Ferrari A, et al.: Salivary gland carcinoma in children and adolescents: The EXPeRT/PARTNER diagnosis and treatment recommendations. Pediatr Blood Cancer 68 (Suppl 4): e29058, 2021.
- Ryan JT, El-Naggar AK, Huh W, et al.: Primacy of surgery in the management of mucoepidermoid carcinoma in children. Head Neck 33 (12): 1769-73, 2011.
- Morse E, Fujiwara RJT, Husain Z, et al.: Pediatric Salivary Cancer: Epidemiology, Treatment Trends, and Association of Treatment Modality with Survival. Otolaryngol Head Neck Surg 159 (3): 553-563, 2018.
- Grant SR, Grosshans DR, Bilton SD, et al.: Proton versus conventional radiotherapy for pediatric salivary gland tumors: Acute toxicity and dosimetric characteristics. Radiother Oncol 116 (2): 309-15, 2015.
- Mao MH, Zheng L, Wang XM, et al.: Surgery combined with postoperative (125) I seed brachytherapy for the treatment of mucoepidermoid carcinoma of the parotid gland in pediatric patients. Pediatr Blood Cancer 64 (1): 57-63, 2017.
- Drilon A, Siena S, Ou SI, et al.: Safety and Antitumor Activity of the Multitargeted Pan-TRK, ROS1, and ALK Inhibitor Entrectinib: Combined Results from Two Phase I Trials (ALKA-372-001 and STARTRK-1). Cancer Discov 7 (4): 400-409, 2017.
- Drilon A, Laetsch TW, Kummar S, et al.: Efficacy of Larotrectinib in TRK Fusion-Positive Cancers in Adults and Children. N Engl J Med 378 (8): 731-739, 2018.