Abstract
BackgroundImage guidance in radiation oncology has resulted in significant improvements in the accuracy and precision of radiation therapy (RT). Recently, the resolution and quality of cone beam computed tomography (CBCT) for image guidance has increased so that tumor masses and lymph nodes are readily detectable and measurable. During treatment of head and neck squamous cell carcinoma (HNSCC), on-board CBCT setup imaging is routinely obtained; however, this CBCT imaging data is not utilized to predict patient outcomes. Here, we analyzed whether changes in CBCT measurements obtained during a course of radiation therapy correlate with responses on routine 3-month follow-up diagnostic imaging and overall survival (OS).Materials/methodsPatients with oropharyngeal primary tumors who received radiation therapy between 2015 and 2018 were included. Anatomical measurements were collected of largest nodal conglomerate (LNC) at CT simulation, end of radiation treatment (EOT CBCT), and routine 3-month post-RT imaging. At each timepoint anteroposterior (AP), mediolateral (ML) and craniocaudal (CC) measurements were obtained and used to create a 2-dimensional (2D) maximum.ResultsCBCT data from 64 node positive patients were analyzed. The largest nodal 2D maximum and CC measurements on EOT CBCT showed a statistically significant correlation with complete response on 3-month post-RT imaging (r = 0.313, p = 0.02 and r = 0.318, p = 0.02, respectively). Furthermore, patients who experienced a 30% or greater reduction in the CC dimension had improved OS (Binary Chi-Square HR 4.85, p = 0.028).ConclusionDecreased size of pathologic lymph nodes measured using CBCT setup imaging during a radiation course correlates with long term therapeutic response and overall survival of HNSCC patients. These results indicate that CBCT setup imaging may have utility as an early predictor of treatment response in oropharyngeal HNSCC.
Highlights
Head and Neck Squamous Cell Carcinoma is a significant health issue with more than 600,000 new cases of head and neck squamous cell carcinoma (HNSCC) diagnosed worldwide and more than 60,000 new cases per year in the United States [1]
Decreased size of pathologic lymph nodes measured using cone beam computed tomography (CBCT) setup imaging during a radiation course correlates with long term therapeutic response and overall survival of HNSCC patients
These results indicate that CBCT setup imaging may have utility as an early predictor of treatment response in oropharyngeal HNSCC
Summary
Head and Neck Squamous Cell Carcinoma is a significant health issue with more than 600,000 new cases of HNSCC diagnosed worldwide and more than 60,000 new cases per year in the United States [1]. Innovations including Varian’s Iterative CBCT have tremendously improved the resolution and quality of cone beam computed tomography (CBCT) such that discrete masses and lymph node conglomerates are readily discernable [5,6,7]. This large dataset of CT information has not been routinely used to monitor treatment responses largely because of the low resolution of CBCT in the past. The resolution and quality of cone beam computed tomography (CBCT) for image guidance has increased so that tumor masses and lymph nodes are readily detectable and measurable. At each timepoint anteroposterior (AP), mediolateral (ML) and craniocaudal (CC) measurements were obtained and used to create a 2-dimensional (2D) maximum
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