From the Guidelines
Pleomorphic adenomas have a low recurrence rate after complete surgical resection, typically ranging from 1-5% over 5-10 years when properly excised. The clinical behavior of these tumors is similar to low-grade salivary gland cancers, which have been shown to have excellent disease control when managed with complete surgical resection, even with narrow surgical margins, in the absence of adverse features such as perineural or lymphovascular invasion or pathologic nodal disease 1. Recurrence usually happens slowly, with most cases appearing 5-15 years after the initial surgery.
Key Factors Influencing Recurrence
- The risk of recurrence depends significantly on the surgical approach used, with superficial or incomplete removal (enucleation) leading to higher recurrence rates of 20-45%
- Complete excision with a margin of normal tissue (superficial or total parotidectomy) results in much lower recurrence rates
- Factors that increase recurrence risk include tumor location (especially in the deep lobe of the parotid gland), tumor size, younger patient age, and cellular characteristics showing increased myxoid stroma
Management and Follow-Up
Regular follow-up examinations are recommended for at least 10 years after surgery due to the potential for late recurrence, with physical examinations every 6-12 months and imaging studies as clinically indicated. The goal is for complete excision, but there is not a need to remove additional parotid tissue containing adjacent lymph nodes because of the low rate of metastatic spread 1.
From the Research
Recurrence Rates of Pleomorphic Adenomas
- The recurrence rate of pleomorphic adenomas after resection is high, with 27 out of 84 patients developing a subsequent recurrence in one study 2.
- The interval since last surgery is a significant factor, with patients who had a >10-year interval since their last surgery having a lower subsequent recurrence rate (20% vs 68.2%) 2.
- The number of previous recurrences is also a risk factor, with increasing number of prior recurrences associated with increased risk of subsequent recurrence (hazard ratio, 1.23; 95% confidence interval, 1.13-1.35, P < .001) 3.
Factors Influencing Recurrence
- Incomplete excision, intraoperative capsule rupture, myxoid subtype, presence of satellite nodules and tumor extensions (pseudopodia), and lack of glandular tissue margin are significant risk factors for recurrence 4.
- The experience of the surgeon and the technique of tumor enucleation are also important factors, with parotidectomy being recommended over enucleation to reduce the risk of recurrence 4, 5.
Treatment Options and Outcomes
- Surgical techniques such as superficial or total parotidectomy are recommended to reduce the risk of further recurrence in patients with recurrent pleomorphic adenoma 5.
- Adjuvant radiation therapy (RT) after surgery is associated with a significant decrease in risk of subsequent tumor recurrence (hazard ratio, 0.09; 95% confidence interval, 0.02-0.41, P = .002) 3.
- The optimal management of recurrent pleomorphic adenoma is still arguable, with varying opinions on the surgical extent and the necessity of radiotherapy 6.