ESTRO 2024 - Abstract Book

S1237

Clinical - Head & neck

ESTRO 2024

997

Digital Poster

Impact of Treatment Package Time on Survival in Adenoid Cystic Carcinoma of the Head and Neck

Ela Kini 1 , Demond Handley 2 , Yevgeniya Gokun 2 , Emile Gogineni 3 , Dukagjin M Blakaj 3 , Sujith Baliga 3 , Rafi Kabarriti 4 , Madhur Garg 4 1 Hunter High School, N/A, New York, USA. 2 The Ohio State University Wexner Medical Center, Biostatistics, Columbus, USA. 3 The Ohio State University Wexner Medical Center, Radiation Oncology, Columbus, USA. 4 Montefiore Medical Center, Radiation Oncology, New York, USA

Purpose/Objective:

Adenoid cystic carcinoma (ACC) is a rare and aggressive salivary malignancy, with a propensity for perineural and local tumor invasion, as well as late disease recurrence. The standard of care treatment involves surgical resection followed by post-operative radiotherapy (RT), which has been shown to improve local control. A prolonged treatment package time (TPT), defined as the time from surgery to the end of radiation therapy, been shown to be associated with inferior overall survival (OS) in head and neck squamous cell carcinomas. Given that ACC has slow tumor growth kinetics, it is unclear if there is an impact of prolonged TPT on OS in this tumor histology. Therefore, our objective was to analyze the impact of prolonged TPT (>100 days) on OS in patients with ACC.

Material/Methods:

In this population based retrospective cohort study, we queried the National Cancer Database for patients diagnosed with non-metastatic ACC between the years 2004-2019. All patients were treated with surgery followed by post-operative radiotherapy, with or without chemotherapy. TPT was defined as the number of days from surgery to the end of radiation therapy. Patients were stratified into two groups based on their TPT (≤100 days vs >100 days). Patient clinical and demographic characteristics were analyzed by treatment duration group. Wilcoxon rank sum tests were used to analyze continuous variables and chi- squared or Fisher’s exact test were used to analyze categorical variables as appropriate. Kaplan-Meier curves along with Log-Rank tests were used to assess the association between overall survival and treatment duration groups. A Cox proportional-hazards multivariable model compared two treatment duration groups with adjustment for covariates that were statistically significant (p value < 0.05) in the unadjusted results. All analyses were conducted using SAS v9.4 (SAS Institute, Cary, NC).

Results:

We identified 1,909 patients with ACC, of which 1,251 had a TPT ≤100 days (65.5%) and 658 had a TPT >100 days (34.5%). ACC Patients with a TPT >100 days were more likely to have pathological T4 disease (29.5% vs 22.1%, p<0.001), Medicaid insurance (9.3% vs 5.5%, p<0.001), be of Hispanic race (10% vs 4.7%, p<0.001), have positive margins (51.5% vs 48.1%, p=0.046), more likely to be treated with chemotherapy (13.4% vs 10.1%, p=0.025), and treated to a higher median RT dose (66 Gy vs 64 Gy, p<0.001). The 10- year OS for patients with a TPT ≤100 days vs >100 days was 66% (95% CI:77%-84%) vs 62% (95% CI: 57%-67%), respectively (log-rank, p=0.07). On multivariable analysis, after adjusting for age, sex, insurance, rurality, Charlson-Deyo score, pathological T and N stage, margin