The rising incidence of parotid metastases: our experience from four decades of parotid gland surgery

Secondary neoplasia in the parotid gland is increasingly frequent. We examined outcomes from 40 years of parotid surgery to analyse patterns for metastasis, review the staging procedure and discuss management. We retrospectively examined 772 consecutive cases of parotid surgery in a university hospital between 1975 and 2015 and assessed changes in incidence and management over four decades. In all, 71% percent of patients were male and 29% were female, with a mean age of 68 years, aged between 23 and 93 years. We diagnosed 683 parotid tumours of which 15.8% (n = 108) were malignant; 44% (n = 48) of all malignant lesions were metastases. The incidence of malignant tumours rose from 8% in the first decade, 14% in the second, 17% in the third to 21% in the fourth. The incidence increased even further from 10% in the first to 57% in the final decade. Most frequent tumours were metastases of squamous cell carcinoma (79%), and the majority of these lesions (87%) arose from above the clavicle, with 30 primary tumours in the skin. In most cases, the skin tumour had been excised between 6 and 24 months prior to parotid metastasis. Management consisted of surgery with neck dissection. 48 patients (67%) received adjuvant therapy, but despite aggressive multimodal treatment, disease progressed in the majority of cases, in 57% squamous cell carcinoma of the skin primaries, 67% of mucosal primaries above the clavicle and 83% of infraclavicular primaries. Parotid malignant tumours are increasing in incidence, mostly due to a rise in metastatic malignant tumours within the parotid gland, most of which are metastases of skin tumours, commonly squamous cell carcinoma. Despite multimodal therapy, their recurrence and progression rate remains high. We propose inclusion in head and neck follow-up in all cases of head and neck skin cancers.