SURVive: investigating new imaging criteria for non-operative treatment following neoadjuvant chemoradiation in rectal cancer patients

Following the great success of neoadjuvant treatment, recently, studies have
addressed the non-operative treatment for rectal cancer patients. Especially in
locally advanced rectal cancer, a pathological complete response (pCR) after
chemoradiation therapy correlates positively with outcome and it has been
suggested that these patients could be managed less invasively or even without
surgery. This would be a very important improvement in rectal cancer treatment,
as the current surgical treatment can lead to significant short- and long-term
complications and functional problems in the majority of patients. Up to 20%
of patients have a complete remission of their rectal tumor and lymph nodes
after neoadjuvant treatment. Although this could mean that surgery is no longer
required and major complications can be avoided, these patients (with a
clinical complete response on imaging, cCR) cannot be accurately selected by
the currently available imaging modalities.
Both MRI and FDG-PET/CT have their limitations in the prediction of pCR.
Diffusion Weighted-MRI (DW-MRI) can provide information related to tumor
cellularity and the integrity of cell membranes and is sensitive to
intratumoral changes induced by chemotherapy. Digital FDG-PET/CT visualizes
changes in glucose metabolism and provides higher time-of-flight resolution
images when compared to conventional FDG-PET/CT. The combination of both could
possibly have complimentary value to predict pCR in those patients in whom
surgery could potentially be avoided. Available data in the literature is
currently insufficient to evaluate such a multimodality imaging approach.

Evaluation of the feasibility of the combination of (DW-)MRI and digital
FDG-PET/CT for prediction of response to chemoradiation therapy.

As a pilot study, we want to include 20 patients. All patients who meet the
inclusion criteria are asked to participate in this study. The combined value
of MRI and digital FDG-PET/CT, in the prediction of response to chemoradiation
will be evaluated observationally. Results will be compared to the current
standard imaging methods. Since this trial is a pilot study, no formal power
analysis has been performed.

Patients will receive 3 additional FDG-PET/CT scans and 1 additional (DW-)MRI
scan. Three hours will be calculated for the FDG-PET/CT scan and 2 hours for
the MRI scan.
Radiation of the FDG-PET/CT is minimal and will not lead to any changes in
normal metabolism of the human body.
Only an allergic reaction to the FDG is possible but has only occured in very
few cases. In case of a reaction, trained personell is closeby and will handle
the situation.