Causes of Recurrence
The primary cause of benign parotid tumor recurrences is due to the capsule of the tumor being breached during surgery, and/or pieces of the tumor being left behind. The tumor pieces can be microscopic and not visible to the eye.
If tumor cells are spilled into the gland during surgery, it can cause new tumors to grow in the parotid bed and may cause multiple new tumors to develop.
It generally takes approximately five to seven years for a benign parotid tumor recurrence to grow to a size where it can be felt, and/or to be detected by imaging studies.
The time frame for a recurrence can be shorter or longer depending on the biology of the tumor, and the completeness of the surgery.
There are some benign tumors, and certain malignant tumors, such as adenoid cystic carcinoma or other low-grade cancers, that can recur up to 20 or more years following the initial operation.