Validation of a Predictive Model After Complete Response in Rectal Cancer

General objective

The long-term research objective is to be able to select rectum cancer patients who could receive a less invasive treatment. If prediction of response is possible, surgery may be avoided when complete response after chemoradiotherapy is expected or performed with smaller incisions if stage reduction is significant. This support decision system helps to individualize patient treatment and can improve the quality of life for the patient.

Aim of the study

The main aim is to validate a predictive model for pathologic complete response (ypT0N0) in rectal cancer patients treated with chemoradiotherapy by multi-centric prospective data collection. The second aim is to collect extra data for improvement of the accuracy of the prediction models with new variables. This new model will be validated later in the model development process.

Hypothesis

General hypothesis:

The validated accuracy of predictive models for pathologic complete response after chemoradiotherapy in rectal cancer patients is high enough to tailor treatment (surgery/non-surgery and/or administer extra radiation boosts) in clinical practice.

Specific hypotheses:

• The performance of the developed models on the validation data is at least equal to the performance achieved during the model development process.
• The performance of a new model based on the addition of variables performs better than the previous model

Inclusion criteria

• Histological proven rectal cancer
• UICC stage I-III
• Only primary tumors; no recurrences
• Only concurrent chemoradiotherapy treatment
• Willing and able to comply with the study prescriptions
• 18 years or older
• Have given written informed consent before patient registration
• No previous radiotherapy to the pelvis

Exclusion criteria

• No adenocarcinoma histology
• History of prior pelvis radiotherapy