Tumors can occur in any glands, but parotid glands have a higher incidence of developing abnormal growth of cells. Although most cases are benign, some benign cancers can become malignant over time.1
Benign tumors grow slowly and do not metastasize, but the incidence of malignant transformation increases with the duration of the tumor.2
The size of parotid tumors often depends on the stages and tumor size is measured in centimeters. Tumors can grow as big and invade the arteries.3, 4
Can Benign Parotid Tumors Become Malignant?
Parotid tumors account for 80% of salivary gland cancers and out of which 20% of cases turn malignant. Tumors can occur in any glands, but parotid glands have a higher incidence of developing abnormal growth of cells. Although most cases are benign, some benign cancers can become malignant over time.1
They form a swelling or lump near the jaw, cheek, or in front of the ears. In the regular clinical practice, the parotid masses are removed through surgical resection for the management of the facial nerve. A medical study was conducted on 540 patients who underwent surgery for the removal of the parotid gland. The diagnosis of these patients showed that 470 cases were non-cancerous (benign) and 70 cases were malignant.
The recurrence of benign tumors had a higher incidence when compared to the malignant cases that were removed by parotidectomy. Benign tumors grow slowly with painless masses in the tail of the parotid gland and do not metastasize, but the incidence of malignant transformation increases with the duration of the tumor. Pleomorphic adenoma is the classic example of a benign tumor and mucoepidermoid carcinoma is the most common malignant tumor.2
How Big Are Parotid Tumors?
The TNM system is the most commonly used staging system for cancer. The stages are often based on diagnostic tests and imaging studies.
T (Tumor) – The size of the tumor and determine whether it has spread to the nearby tissues
N (Node) – Refer to the regional lymph node metastases. Where and how it has spread.
M (Metastases)- whether or not it has spread to other parts of the body such as the lungs.
The results are combined to identify the stage of cancer for every individual. Stages are classified from 0 through 4 and each stage shows the growth and size of cancer. The size of parotid tumors often depends on the stages and tumor size is measured in centimeters. Tumors can grow as big and invade the arteries. There is no evidence of malignancy when the tumor stage is T0. The tumor grows up to 2cm when they are T1 stage. The tumor grows large and invasive during stage T2.
During the T3 stage, the tumor grows larger than 6cm and spread to distant parts of the organ beyond the salivary glands and affects the seventh cranial nerve.3, 4
Both benign and malignant tumors can develop anywhere in the salivary gland, but parotid glands have an increased risk of developing this condition. The parotid glands are the largest salivary glands sitting in front of the ears.
Certain factors such as dehydration, smoking, exposure to radiation enhance the risk of developing parotid tumors. The majority of the salivary gland tumors are non-cancerous and may resolve without treatment. But some may turn malignant and cause persistent pain in the area of the salivary gland.
- “Salivary Gland Tumors.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 30 July 2020, www.mayoclinic.org/diseases-conditions/parotid-tumor/cdc-20388269.
- Bussu, F, et al. “Clinical Approach and Treatment of Benign and Malignant Parotid Masses, Personal Experience.” Acta Otorhinolaryngologica Italica : Organo Ufficiale Della Societa Italiana Di Otorinolaringologia e Chirurgia Cervico-Facciale, Pacini Editore SpA, June 2011, www.ncbi.nlm.nih.gov/pmc/articles/PMC3185824/.
- Ho, Kimberley, et al. “An Overview of the Rare Parotid Gland Cancer.” Head & Neck Oncology, BioMed Central, 14 Sept. 2011, www.ncbi.nlm.nih.gov/pmc/articles/PMC3197557/.
- “Salivary Gland Cancer – Stages and Grades.” Cancer.Net, 2 July 2020, www.cancer.net/cancer-types/salivary-gland-cancer/stages-and-grades.