Overview
The aim of the study is to provide prospective data regarding microscopic tumor spread in all directions from the macroscopic tumor in pathology specimens, as seen by eye, and on imaging to define the target volume for endoluminal radiation boosting in rectal cancer patients.
Description
This study is a prospective multicentre cohort trial in ≥50 patients with a residual ycT1-3N0 tumor after neoadjuvant chemoradiotherapy or radiotherapy for rectal adenocarcinoma at least 6 weeks after the neoadjuvant treatment.
In addition to standard workup and treatment (e.g. a flexible endoscopy and an MRI scan at 6-8 weeks post-neoadjuvant therapy), patients will undergo pre-operatively, after induction of general anaesthesia, an endorectal ultrasound and rigid rectoscopy as study procedures if these procedures are not already part of standard workup. Furthermore, the pathological specimens of some patients will be scanned using MR imaging during certain parts of the pathological process.
Objectives include determining the maximum distance of microscopic tumor spread per patient in all directions, creating a tissue deformation model to account for changes due to e.g. fixation and pathological processing, using this tissue deformation model to translate the microscopic tumor spread back to the in vivo situation (e.g. back to in vivo MRI scans, 3D endo-ultrasounds), and evaluating/determining risk factors for the presence and/or extent of microscopic tumor spread.
This data will be used for target volume definition in rectal endoluminal radiation boosting.
Eligibility
Inclusion Criteria:
- ≥18 years of age and capable of giving informed consent.
- ycT1-3N0() residual(*) histology confirmed rectal adenocarcinoma after neoadjuvant radiotherapy or long-course chemoradiotherapy for which patients will undergo TME surgery.
- Minimal interval between end of neoadjuvant chemoradiotherapy or radiotherapy: 6 weeks.
(*)= as determined by clinical assessment (digital rectal examination, endoscopy with or without biopsy) and/or MRI. Biopsy/histology around the time of diagnosis is adequate; no biopsy/histology is needed after neoadjuvant therapy.
(**)= including tumor regrowths/local recurrence after an initial clinical complete response and a "watch and wait" approach. These patients will also be included after the local recurrence has been determined using endoscopy and/or MRI.
Exclusion Criteria:
- Patient has received brachytherapy as part of neoadjuvant treatment.
- <18 years of age or incapable of giving informed consent.
- Patient has not been treated with neoadjuvant radiotherapy or long-course chemoradiotherapy.
- Patient will not undergo TME surgery for a ycT1-3N0 residual histology confirmed rectal adenocarcinoma.
- Interval between end of neoadjuvant therapy and surgery is <6 weeks.