Efficacy and Safety of Conventional Neoadjuvant Therapy Versus Total Neoadjuvant Therapy in Older Patients With Locally Advanced Rectal Cancer

Inclusion criteria

• Age ≥ 70 years old
• ECOG performance status (PS):
• ≤1 if age \> 75 years old
• ≤2 if age ≤ 75 years old
• Histologically or cytologically confirmed adenocarcinoma of the rectum
• Distal border of the tumour below the peritoneal reflection and within 15 cm of the anal verge
• Operable stage III or high-risk stage II rectal cancer (high-risk tumours defined as those having ≥1 of the following features: T4, mesorectal fascia (MRF) involvement/threatening \[i.e.,tumour within 1 mm of the MRF\], extramural venous invasion). Patient with involvement of lateral pelvic lymph nodes are also eligible.
• Adequate bone marrow function as defined below:
• Absolute neutrophil count ≥1,500/µL
• Haemoglobin ≥9 g/dL
• Platelets ≥100,000/µL
• Adequate liver function as defined below:
• Serum total bilirubin ≤1.5 x ULN. In case of known Gilbert's syndrome \<3xUNL is allowed
• AST (SGOT) and ALT (SGPT) ≤2.5 x ULN
• Alkaline phosphatase ≤2.5 x ULN
• Adequate renal function as defined by estimated glomerular filtration rate (GFR) ≥30 mL/min/1.73m² (according to the CKD-EPI 2021 equation).
• Absence of clinical conditions that in the opinion of the investigator, would contraindicate neoadjuvant therapy and/or surgery.
• Signed Informed Consent form (ICF) obtained prior to any study related procedure.
• Male subjects with partners of childbearing potential must agree to use condom during the course of this study and for at least 6 months after the last administration of study drugs.

Exclusion criteria

• Extensive growth into cranial part of the sacrum (above S2/3 junction) or the lumbosacral nerve roots indicating that surgery will never be possible even if substantial tumour down-sizing is achieved.
• Presence of metastatic disease or recurrent rectal tumour.
• Presence of grade ≥2 peripheral neuropathy according to the Common Toxicity Criteria for Adverse Events (CTCAE) v.5.0.
• Significant medical, neuro-psychiatric, or surgical condition, currently uncontrolled by treatment, which, in the principal investigator's opinion, may interfere with completion of the study.
• Any contraindication to pelvic irradiation as evaluated by the investigator.
• Known hypersensitivity reactions to the study drugs or to any excipients, premedications or non-investigational medicinal products or concomitant medications.
• Any investigational anti-cancer therapy other than the protocol specified therapies (participation in other prospective studies which do not imply any specific intervention may be allowed after discussion with the Study Chair).
• Patients with a prior or concurrent malignancy whose natural history or treatment has the potential to interfere with the safety or efficacy assessment.
• Clinically significant (i.e., active) cardiovascular disease: cerebral vascular accident/stroke, myocardial infarction, unstable angina, congestive heart failure (grade III or IV as classified by the New York Heart Association), or serious cardiac arrhythmia requiring medication within the past 6 months.
• Complete dihydropyrimidine dehydrogenase (DPD) deficiency.
• Any previous treatment for rectal cancer.
• Use of brivudine, sorivudine or their chemically related analogues.