Functional imaging-guided radiotherapy dose escalation in rectal adenocarcinoma: a feasibility study

Interventions: This study will evaluate the feasibility of a diffusion-weighted magnetic resonance imaging (DW-MRI) guided radiotherapy boost for locally advanced rectal cancer.
Patients will undergo pre-treatment MRI in the fortnight prior to commencing radiotherapy (+/- chemotherapy). Boost volume will be defined quantitatively according to intratumoural apparent diffusion coefficient (ADC) value. This volume will be targeted for a single-fraction 5-10Gy boost 3-5 days prior to commencing standard radiotherapy (50Gy delivered in 25 fractions).
Treatment will be administered by the Radiation Oncology department at Sunshine Coast University Hospital (SCUH), Birtinya. Each treatment takes approximately 15 minutes per day. Patients will be reviewed once per week by radiation oncology medical staff as per normal practice. Patients will also be asked to complete a quality of life questionnaire at several timepoints prior to, during and following completion of the treatment course, which will take an additional 5-10 minutes on each occasion.
Primary outcome(s): Rate of radiotherapy-related treatment toxicity as per Common Terminology Criteria for Adverse Events v5.0[Acute toxicity: throughout and up to 3 months after treatment
Late toxicity: assessed at 3-12 monthly intervals after completion of treatment]
Study Design: Purpose: Treatment; Allocation: Non-randomised trial; Masking: Open (masking not used);Assignment: Single group;Type of endpoint: Safety/efficacy