Comparison of pathological response rates in long-term chemoradiotherapy versus short-term radiotherapy in the total neoadjuvant treatment of patients with locally advanced rectal cancer in the context of a randomized clinical trial

Evaluation of pathologic response following long-course chemoradiotherapy versus short-course radiotherapy in total neoadjuvant treatment of patients with locally advanced rectal cance

Randomized clinical trial, parallel-group, phase 2. In this study, patients are allocated to two treatment groups (Group A: long-course chemoradiation, Group B: short-course radiotherapy). Randomization is performed using the RAND function in Microsoft Excel. The total sample size is 60 patients (30 patients per group).

This study is a phase 2 randomized clinical trial conducted at Shahid Rajaei Hospital, Babolsar, Iran. Eligible patients with locally advanced rectal adenocarcinoma are recruited from the hospital’s oncology and colorectal surgery clinics.

Patients aged over 18 years with locally advanced rectal adenocarcinoma located within 16 cm from the anal verge, who are clinically eligible for surgery following neoadjuvant treatment, and who do not meet any of the exclusion criteria—including histology other than adenocarcinoma, synchronous adenocarcinoma elsewhere in the colon, history of prior malignancy (except basal cell carcinoma of the skin), prior chemotherapy, prior pelvic radiotherapy, inflammatory bowel disease, or bilateral hip prostheses—will be eligible for inclusion in the study.

patients aged ≥18 years with biopsy-confirmed rectal adenocarcinoma located ≤16 cm from the anal verge, clinical stage cT3–T4 or regional lymph node-positive, ECOG 0–2, without distant metastasis, and meeting standard laboratory criteria. Patients with synchronous colorectal cancer, prior malignancy (except BCC), prior chemotherapy or pelvic radiotherapy, inflammatory bowel disease, or bilateral hip prostheses will be excluded.

Pathologic complete response, pCR

In this study, a blocked randomization method with double and quadruple permutations will be used to allocate patients to the two groups. In this method, two- and four-patient blocks, each comprising combinations of the two treatment arms, are created. To prevent predictability of future treatment assignments, the order of the blocks is determined using a random number table. Accordingly, for a sample size of 60 patients, ten four-patient blocks will be selected from the combinations AABB, ABAB, ABBA, BABA, BBAA, and BAAB, and ten two-patient blocks will be selected from the combinations AB and BA, using a random number table.

In this study, anonymized raw and processed data will be collected, including patient demographic characteristics, tumor features, details of neoadjuvant treatment (chemotherapy and radiotherapy), surgical findings, pathological outcomes (including pathological complete response), and treatment-related outcomes and toxicities. In addition, the study protocol, data collection forms, and final statistical analysis reports will be available for sharing. After completion of the study and publication of the results, de-identified data will be shared exclusively for research purposes upon formal request and approval by the principal investigator. Data sharing will be conducted in compliance with ethical standards, patient confidentiality, and non-commercial use policies.

Start of access period: 6 months after publication of the results

Researchers affiliated with academic and scientific institutions

The data and documents generated in this study will be available solely for scientific research purposes, including secondary analyses, systematic reviews, and meta-analyses, with the aim of advancing scientific knowledge in the field of rectal cancer treatment. Access to the data will be granted upon formal request and approval by the principal investigator, subject to compliance with research ethics principles, protection of patient confidentiality, and complete anonymization of participant information. The data may be used exclusively for non-commercial and academic research purposes.

shabnam Ashofte 09353413556

All requests for access to the study data or documents must be submitted in writing to the principal investigator. Upon receipt, the principal investigator will review and evaluate the request, and if approved, access to the data will be provided in anonymized files, in compliance with confidentiality and research ethics principles. All use of the data is strictly limited to research and non-commercial purposes, and recipients are required to adhere to the terms of use and not disclose any identifiable patient information.”