Adenoid Cystic Carcinoma of the Skull Base: Response to Radiation Therapy and Outcomes in a Retrospective Case Series

Long-term outcomes after particle radiation therapy in patients with nasopharyngeal adenoid cystic carcinoma

BACKGROUND

Nasopharyngeal adenoid cystic carcinoma (NACC) is a relatively rare salivary gland tumor that is generally associated with poor outcomes. High-dose radiotherapy is a key treatment for patients with NACC. This study reported the long-term efficacy and safety of particle beam radiation therapy (PBRT) for NACC.

METHODS AND MATERIALS

Twenty-six patients with nonmetastatic NACC who received definitive PBRT alone were included in this retrospective study. The majority of patients (92.3%) had locally advanced disease. Twenty-five (96.15%) patients received intensity-modulated proton radiotherapy (IMPT) followed by a carbon ion radiotherapy (CIRT) boost, and one patient received CIRT alone. Overall survival (OS), local control (LC), regional control (RC), and distant metastasis control (DMC) rates were calculated via the Kaplan-Meier method.

RESULTS

The median follow-up time was 46.95 months for the entire cohort. Seven patients experienced local recurrence, and one patient experience neck lymph node recurrence. The 3- and 4-year OS, LC, RC, and DMC rates were 100% and 91.7%, 92.3% and 84.6%, 95.8% and 87.8%, and 90.2% and 71.3%, respectively. A total of 91.3% of the patients achieved complete remission of gross tumors at 1 year after PBRT. Severe acute toxicity was observed in only two patients. A grade 4 decrease in visual acuity was observed in one patient with orbital apex invasion. No late grade 3 or 5 toxicity was observed.

CONCLUSION

Definitive PBRT provided a satisfactory 4-year OS for patients with locally advanced NACC. The toxicity was acceptable and mild. Further follow-up is necessary to confirm the efficacy and safety of definitive PBRT for patients with NACC.

Proton therapy and/or helical tomotherapy for locally advanced sinonasal skull base adenoid cystic carcinoma: Focus on experience of the Institut Curie and review of literature

BACKGROUND

Sinonasal adenoid cystic carcinomas (SNACC) have high propensity for skull base (SB) infiltration. Unresectability or incomplete surgical resection in such cases make radiotherapy treatment paramount. Curative dose escalation is challenging because of adjacent organs at risk, especially in locally advanced cases.

METHODS

Eighteen patients that had locally advanced SB SNACC with unresectable or incomplete surgical resection treated by proton therapy and/or helical tomotherapy at Institut Curie between 3/2010 and 8/2020 were retrospectively included.

RESULTS

After median follow-up of 52 months, 5-year OS, LRRFS, DMFS, DFS rates were, respectively, 47% (95%CI: 26-83), 50% (95%CI: 36-88), 39% (95%CI: 26-81), 33% (95%CI: 22-73). One patient had grade 4 late optic nerve disorder. Eight patients had grade 3 late toxicity including mainly hearing impairments.

CONCLUSION

Proton therapy and helical tomotherapy are effective and safe methods for curative dose escalation of locally advanced SB SNACC, which are a poor prognosis subgroup. Available literature suggests carbon-ion therapy could be an efficient alternative.

Posterior fossa giant adenoid cystic carcinoma with skull base invasion mimicking glomus jugulare: A case report and review of literature

The author describes a rare case of giant adenoid cystic carcinoma (ACC) mimicking large paraganglioma with lower cranial nerve palsy. A 60-year-old female presented with a progressive increase in postauricular swelling with unilateral hearing loss, facial deviation, difficulty in swallowing, and hoarseness of voice. MRI brain showed highly vascular infiltrating and osteolytic mass suggestive of large glomus jugulare versus sarcoma. It was completely engulfing the jugular foramen and lower cranial nerves with bony erosion of the jugular foramen and occipital condyle. The whole mastoid was filled with the tumor. On digital subtraction angiography the majority of blood supply was from the occipital branch of the external carotid artery and vertebral artery. The patient underwent percutaneous embolization followed by external carotid ligation and resection of the mass. The postoperative course was uneventful. Histopathology was suggestive of mixed ACCs. The patient received radiotherapy. After 1 year of follow up no recurrence or distant metastasis was noted.

Adenoid Cystic Carcinoma of the Nasopharynx with Skull Base Involvement: Retrospective National Cohort Analysis of Treatment Paradigms, Outcomes, and Provider Density

Objectives This article examines a national cohort of patients with nasopharyngeal adenoid cystic carcinoma (ACC) for incidence, skull base invasion, overall survival, and treatment paradigms.

Design, Setting, and Participants Retrospective national population-based study using Surveillance, Epidemiology, and End Results program data of patients with ACC of the nasopharynx (NACC) and skull base between 2004 and 2016.

Main Outcomes and Measures Primary outcomes included 5-year overall survival and odds of radiation treatment. Statistical analysis was performed using STATA 15.0 (STATACorp). p-Values < 0.05 were considered statistically significant.

Results Of the 2,385 cases of ACC, 70 cases were classified as NACC. Twenty-one percent (15) involved invasion of the skull base or posterior pharyngeal wall, and 42% (30) were either stage 3 or stage 4. The 5-year overall survival for patients with NACC without skull base invasion was 67% which dropped to 40% with invasion into the skull base. Radiation was used as the primary form of therapy for 62% of NACC and 73% of NACC invading into skull base. Odds of receiving radiation therapy and 5-year survival were not affected by socioeconomic status or density of providers.

Conclusion NACC is rare in incidence and was most commonly treated with radiation therapy when advanced in stage. Prognosis was dependent on invasion through posterior pharyngeal wall and skull base. Provider density and socioeconomic status did not affect odds of radiation or overall survival for NACC.