Excellent long-term patient-reported quality of life and low levels of treatment regret after surgery and adjuvant radiation therapy for primary salivary gland malignancies

Background: Surgical resection is the mainstay of curative treatment for localised salivary gland malignancies of the head and neck, with adjuvant radiation therapy (RT) indicated in the presence of high-risk features to reduce the risk of recurrence. Most patients survive for many decades after locoregional treatment and thus understanding the impact of treatment(s), particularly RT, on long term quality of life (QOL) is critical. This study aimed to investigate the long-term QOL of patients treated with surgery and adjuvant RT for primary salivary gland malignancies of the head and neck, and to assess for potential predictors of QOL which might guide refinement of current treatments and improve survivorship care. Methods: This retrospective cohort study included patients who underwent surgery and post-operative RT for primary malignant salivary gland tumours of the head and neck at a single tertiary cancer centre between 2006 and 2022. Patient, tumour and treatment information was extracted from a prospectively maintained database. Patients who were still alive were contacted to complete a QOL survey. Kaplan-Meier survival analysis was used to summarise overall survival (OS) and disease-free survival (DFS), with log-rank test used to assess prognostic factors. Univariate binary logistic regression model was used to identify factors associated with worse QOL. Results: Sixty-seven patients underwent surgery and RT during the study period. Median follow up was 4.4 years [interquartile range (IQR), 2.4–7.4 years] for all patients and 5.2 years (IQR, 3.9–9.2 years) for patients who completed the QOL survey 5-year OS and DFS and local failure rates were 79%, 79% and 3% respectively (all patients). Twenty-nine patients completed the QOL survey, of which 93% were in remission. Most patients (79%) reported their health as the same or better than before RT. Almost all patients (90%) had no treatment regret regarding receipt of adjuvant RT. Conclusions: Surgery and adjuvant RT achieves durable local control, excellent patient reported QOL and low levels of treatment regret in patients with high-risk primary salivary gland malignancies. However, survivorship care remains a key issue in patents with potentially lengthy survival. Future prospective studies may identify novel biomarkers to further refine patient selection for adjuvant RT, while longitudinal QOL assessment will assist in further refining survivorship protocols.