Abstract

Muhammad Shahid Iqbal¹, Fatima Jamil², Josef Kovarik², Michelle Cunnell³, Charles Kelly¹, Santu Saha⁴, Rahul Patil¹, James O'Hara⁵, David Hamilton⁵, Hannah Fox⁵, Laura Warner⁵, Omar Ahmed⁶, Anthony Waton¹, Daniel Saleh⁶

¹Northern Centre for Cancer Care, Clinical Oncology, Newcastle upon Tyne, United Kingdom; ²Northern Centre for Cancer Care , Clinical Oncology, Newcastle upon Tyne, United Kingdom; ³Northern Centre for Cancer Care, Medical Oncology, Newcastle upon Tyne, United Kingdom; ⁴Newcastle University, Academy of Medical Sciences, Newcastle upon Tyne, United Kingdom; ⁵Freeman Hospital, Head and Neck surgery, Newcastle upon Tyne, United Kingdom; ⁶Freeman Hospital, Plastic surgery, Newcastle upon Tyne, United Kingdom

To investigate the factors affecting the survival outcomes of patient's with carcinoma of the parotid gland treated with surgery and postoperative radiotherapy (S+RT) or radical radiotherapy (RT) who were unfit or declined surgery. 

77 patients treated with S+RT or RT in Newcastle upon Tyne from January 2009 to December 2019 were included in this retrospective study.  Data were collected retrospectively. Survival analysis was performed using log rank analysis and cox regression. 

There were 40 males and 37 females. Sixty five patients were treated with S+RT and 12 patients were treated with RT. 38/77 patients were ≤60 and remaining 39/77 patients were >60 years age; this difference was significant as younger patients had better overall survival (OS) (p <0.001). In terms of T-stage, 15 patients were with T1, 25 with T2, 14 were with T3 and 23 with T4 disease. T-stage by itself was not a significant factor (p 0.117). With regards to N-stage, 47 patients were with N0, 10 with and N1, 18 with N2 and 2 patients were with N3 disease and this N-stage was not prognostic factor (p 0.294). In terms of overall stage, 13 patients were with stage I, 18 with stage II, 12 with stage III, and 34 with stage IV.  Overall stage was not significant factor either (p 0.167). Eighteen patients had adenocarcinoma, 11 patients had squamous cell carcinoma (SCC) differentiation with no obvious skin primary, 10 patients had other high-grade histology and remaining 38 patients had other low-grade histology (including acinic cell, adenoid cystic, mucoepidermoid) and this difference was statistically significant as SCC had the worst OS (p 0.001).Six patients also had addition of concomitant chemotherapy to the radiotherapy and this factor was not significant (p 0.676).

Intent of treatment was a significant prognostic factor. The mean OS was 104 months (95%CI: 89.3–119.0) for S+RT cohort versus 38 months (95%CI: 15.5-60.6) for the RT alone cohort, p< 0.0001. Estimated 5-year OS for S+RT group was 68.4% and for RT group was 28.1% [Figure 1]. Cox regression analysis showed that S+RT group had 0.243 times less risk of dying as compared to that of RT group (p 0.001). Even for progression free survival (PFS), S+RT group had better PFS than RT group (mean PFS 93.38 months with SE 6.34 vs 39.93 with SE 12.0, p 0.001). Females had better survival (p 0.001). Patients were treated with either 60-65Gy in 30 fractions or 50-55Gy in 20 daily fractions and this dose fractionation was not a significant factor for OS (p 0.70).

5 patients (7%) had local recurrence, 4 regional (5%) and 16 (21%) developed distant metastasis. Age (p 0.022) and N-stage (p 0.003) were significant factors for PFS whilst gender, dose fractionation, T & overall-stage and histology were not.

Our analysis showed that patients with parotid carcinoma who had radical radiotherapy alone had worst prognosis. Male gender, age >60 at diagnosis and SCC histology were associated with worst survival.