Short-course Radiotherapy With Induction and Consolidation Chemotherapy in Patients With Locally Advanced Rectal Cancer

Phase II Study of Short-course Radiotherapy With Induction and Consolidation Chemotherapy in Patients With Locally Advanced High-risk Rectal Cancer

Short-course radiotherapy followed by consolidation chemotherapy has shown a better response rate when compared to chemoradiotherapy treatment.

In addition, recent studies have shown better tolerance with total neoadjuvant treatment, with induction or consolidation chemotherapy. Induction chemotherapy could reduce the size of the tumor, treat micrometastases early and allow treatment to start immediately (avoiding potential delays in waiting for radiotherapy). While consolidation chemotherapy allows longer waiting times for surgery, with higher response rates.

Methods: This trial aim to evaluate induction treatment with CAPOX, followed by short-course radiotherapy consolidation chemotherapy with CAPOX. After 5-7 weeks, patients will be evaluate by MRI. Patients with incomplete clinical response will be referred to immediate surgery and patients with complete clinical response will be managed with "watch and wait" approach. Patients with progression disease during the treatment phase will be withdrawn from the study and will receive their treatment according to the investigator's judgment.

The sample size was calculated according to Simon's optimal two-stage design. Accordingly, 21 patients must be included in each group during the first stage and 24 during the second stage. Treatment regimen will be considered effective if 9 or more patients show good response (final analysis), reaching 80% power with an alpha of 0.10 level of significance.

Inclusion Criteria:

• Histologically confirmed adenocarcinoma of mid or low rectum
• Locally advanced rectal cancer with one of the high-risk factors confirmed by high-resolution thin-slice Magnetic resonance image (3 mm) tumors extending to within 1 mm of, or beyond the mesorectal fascia; tumor extending 5 mm or more into perirectal fat; resectable cT4 tumors; lower third; nodal involvement; extramural vascular invasion
• ECOG performance status of 0-2
• An informed consent has been signed by the patient

Exclusion Criteria:

• Upper rectal cancer
• Metastatic disease
• The patient received any previous therapy for colorectal cancer or another malignancy
• Other malignant tumours within the last 5 years except cervical carcinoma in situ and basal cell carcinoma of the skin
• Previous thromboembolic or haemorrhagic events within 6 months prior to registration
• Patients with malabsorption syndrome or difficulties in swallowing
• The patient has severe underlying diseases or poor condition to receive chemotherapy or radiotherapy
• Pregnant of breastfeeding women
• The patient who participate in another clinical trial, or receives any drug for the trial
• Uncontrolled peripheral neuropathy (more than grade 2)