Should Skull Base Surgery Be Offered for Patients with Adenoid Cystic Carcinoma?

The management of head & neck adenoid cystic carcinoma (ACC) involving the skull base appears to vary from center to center, ranging from biopsy/interval imaging/radiotherapy with palliative intent to radical surgical resection and radiotherapy. It is unclear to what extent intervention results in local disease control, or prevents proliferation to systemic disease and whether this impacts on survival.

We aimed to explore our evolving approach to patients with ACC extending to the skull base and to summarize our approach in a suggested management algorithm.

We retrospectively analyzed all case notes of patients with ACC referred to our skull base MDT from June 2005 to date. Their outcomes were analyzed.

Twenty four patients (9 males / 15 females) were identified. The primary site was lacrimal (n = 8), submandibular (n = 3), parotid (n = 4), and minor salivary gland (n = 9). Twelve of the twenty four patients underwent craniofacial resection. Ten of these received adjuvant radiotherapy with two not receiving any adjuvant therapy. In ten patients we provided the initial treatment intervention; two patients had previous surgical resection; one patient had radiotherapy; and one had both previous surgery and radiotherapy. Significant complications occurred in 40% of those operated, i.e., flap failure / CSF leak. Currently 67% of patients operated on are alive and radiological free of local disease recurrence. Out of the twelve patients that did not receive surgery, seven had radiotherapy and five were managed palliatively.

We suggest consideration of extending the limits of resection of ACC to above the skull base when disease is neurotropic and low grade and also suggest the use of gamma knife boost to the cavernous sinus as an adjuvant option. Based on patterns of neurotropic spread we propose a four grade staging system for each of the three primary ACC tumor sites (lacrimal, minor salivary and parotid/submandibular). As a starting point for determining management of this rare tumor type, we suggest a treatment algorithm based on our staging system taking into account non-neurotropic tumor behavior, growth rate, histology and presence of metastatic disease.