Evaluation of survival outcomes and prognostic factors in acinic cell carcinomas of the parotid gland receiving adjuvant radiotherapy

Abstract

Aim: To evaluate the survival outcomes and prognostic factors in acinic cell carcinoma of the parotid gland, a retrospective study was designed. Material and Method: Consecutive patients diagnosed with parotid acinic cell carcinoma and treated with surgery and adjuvant radiotherapy were retrospectively reviewed. Data regarding age, sex, TNM stage, pathologic characteristics, treatment details, and follow-up examinations were collected and analysed. The primary end-point was overall survival; the distant metastasis free survival was calculated from the date of surgery to the date of death or the latest follow-up examination and analysed by the Kaplan-Meier method. Independent prognostic factors were evaluated by the Cox proportional hazards method. Results: Between years of 2010-2020, two radiotherapy centers’ database were reviewed. A total of 32 patients were included. The median age was 55 years (35-80 years). Four-teen (43.75%) were male and 18 (56.25%) were female. Median follow-up was 44 months (8-120). Seven (21.9%) were in T1, 7 (21.9%) in T2, 6 (18.8%) in T3 and 12 (37.5%) in T4 at the time of diagnosis. In all cohort, 6 (18.8%) of them had lymph node metastasis. The 2-year and 5-year OS rates were 92.6% and 78.5%, locoregional recurrence-free survival rates were 100% and 89.1%, distant metastasis free survival rates were 85.9% and 85.9%, respectively. Locoregional recurrence detected in 2 (6.25%), distant metastases detected in 4 (12.5%) patients. All distant metastases detected in the lungs. Univariate analysis showed that age, gender, margin status, T stage, facial nerve involvement, lymphovascular invasion, and perineural invasion were not significantly related to overall survival (all p>0.05). Lymph node involvement (p<0.013) and grade (p<0.006) were the only significant prognostic factors for OS. In multivariate analysis, both lymph node involvement (p<0.050) and grade (p<0.028) remained the significant prognostic factors. Conclusion: In acinic cell carcinoma of the parotid gland, high-grade histology and node positivity are independent variables that affect OS. Since survival is lower in these patient groups, it is imperative to explore other treatment options in addition to adjuvant radiotherapy.

Keywords

• Parotid cancer
• acinic cell carcinoma
• prognostic factors
• radiotherapy
• survival

References

1. Khelfa Y, Mansour M, Abdel-Aziz Y, et al. Relapsed acidic cell carcinoma of the parotid gland with diffuse distant metastasis: case report with literature review. Med High Impact Case Rep 2016; 4: 2324709616674742.
2. Son E, Panwar A, Mosher C, et al. Cancers of the major salivary gland. J Oncol Pract 2018; 14: 99–108.
3. Godwin JT, Foote FW, Frazell EL. Acinic cell adenocarcinoma of the parotid gland; report of twenty-seven cases. Am J Pathol 1954; 30: 465–77.
4. Buxton RW, Maxwell JH, French AJ. Surgical treatment of epithelial tumors of the parotid gland. Surg Gynecol Obstet 1953; 97: 401–16.
5. Al Zaher N, Obeid A, Al-Salam S et al. Acinic cell carcinoma of the salivary glands: a literature review. Hematol Oncol Stem Cel Ther 2009; 2: 259–64.
6. Cavaliere M, De Luca P, Scarpa A et al. Acinic cell carcinoma of the parotid gland: from pathogenesis to management: a literature review. Eur Archi Otorhinolaryngol 2020; 277: 2673-9.
7. Düzova M, Turkan TS. Survival outcomes and prognostic factors in salivary gland cancers treated by surgery and adjuvant radiotherapy. Namık Kemal Tıp Derg 2021; 9: 108-15.
8. Bianchini C, Ciorba A, Stomeo F, et al. A case of parotid acinic cell carcinoma in a young boy. Brazilian J Otorhinolaryngol 2011; 77: 402.

9. Thompson L. World Health Organization classification of tumours: pathology and genetics of head and neck tumours. Ear Nose Throat J 2006; 85: 74.
10. Vander Poorten V, Triantafyllou A, Thompson LDR, et al. Salivary acinic cell carcinoma: reappraisal and update. Eur Archi Otorhinolaryngol 2016; 273: 3511-31.
11. Fang Q, Wu J, Du W, et al. Predictors of distant metastasis in parotid acinic cell carcinoma. BMC Cancer 2019; 19: 1-6.
12. van Weert S, Valstar M, Lissenberg-Witte B, et al. Prognostic factors in acinic cell carcinoma of the head and neck: The Amsterdam experience. Oral Oncology 2022; 125: 105698.
13. Grasl S, Janik S, Grasl M, et al. Nodal metastases in acinic cell carcinoma of the parotid gland. J Clin Med 2019; 8: 1315.
14. Rodriguez-Cuevas S, Labastida S, Baena L, et al. Risk of nodal metastases from malignant salivary gland tumors related to tumor size and grade of malignancy. Eur Archi Otorhinolaryngol 1995; 252: 139-42.
15. Napier SS, Herron BT, Herron BM. Acinic cell carcinoma in Northern Ireland: a 10-year review. British J Oral Maxillofac Surg 1995; 33: 145-8.
16. Mariano FV, Da Silva SD, Chulan TC, et al. Clinicopathological factors are predictors of distant metastasis from major salivary gland carcinomas. Int J Oral Maxillofac Surg 2011; 40: 504-9.
17. Zenga J, Parikh AS, Emerick KS, et al. Close margins and adjuvant radiotherapy in acinic cell carcinoma of the parotid gland. JAMA Otolaryngol Head Neck Surg 2018; 144: 1011-6.
18. Gomez DR, Katabi N, Zhung J, et al. Clinical and pathologic prognostic features in acinic cell carcinoma of the parotid gland. Cancer 2009; 115: 2128-37.
19. Vander Poorten V, Triantafyllou A, Thompson LDR, et al. Salivary acinic cell carcinoma: reappraisal and update. Eur Archi Otorhinolaryngol 2016; 273: 3511-31.
20. Spafford PD, Mintz DR, Hay J. Acinic cell carcinoma of the parotid gland: review and management. J Otolaryngol 1991; 20: 262-6.
21. Greig SR, Chaplin JM, McIvor NP, et al. Acinic cell carcinoma of the parotid gland: Auckland experience and literature review. ANZ J Surg 2008, 78: 754-8.