Trial A: A multicenter, prospective, randomized trial to compare neoadjuvant
chemoradiotherapy (NCRT) followed by radical surgery with surgery alone for cT3a-bN0-1aM0 mid
rectal cancer.
Research objects: Patients with locally advanced rectal cancer, being clinically staged
T3a-bN0-1aM0 by rectal MRI and/or endorectal ultrasonography (ERUS), the tumor being located
6-12 cm above the anal verge.
After giving fully informed consent, the prospective participants will be randomly divided
into two groups, receiving the following two treatment modalities.
Group A1: radical surgery + adjuvant chemotherapy (ACT) Group A2: NCRT + radical surgery +
ACT
Trial B: A multicenter, prospective, randomized trial to compare combined versus single-agent
chemotherapy with concurrent radiotherapy for cT4NanyM0 or cTanyN2M0 rectal cancer.
Research objects: Patients with locally advanced rectal cancer, being clinically staged
cT4NanyM0 or cTanyN2M0 by rectal MRI and/or ERUS, or patients with any other risk factors for
tumor relapse.
After giving fully informed consent, the prospective participants will be randomly divided
into two groups, receiving the following two treatment modalities.
Group A1: NCRT with combined chemotherapy (Capox regimen) + radical surgery + ACT Group A2:
NCRT with single-agent chemotherapy (Capecitabine) + radical surgery + ACT
Trial C: A multicenter, prospective, randomized trial to compare transanal ndoscopic
microsurgery (TEM) excision versus radical resection of rectal cancer being staged clinical
complete response (cCR) after NCRT.
Research objects: Patients with locally advanced rectal cancer, being clinically staged cCR
after NCRT.
After giving fully informed consent, the prospective participants will be randomly divided
into two groups, receiving the following two treatment modalities.
Group A1: TEM excision + ACT Group A2: radical surgery + ACT
Trial D: A prospective, observational study to determine the value of circulating tumor DNA
(ctDNA) for predicting the therapeutic effects of NCRT for locally advanced rectal cancer and
the patients' long-term prognosis.
Research objects: Patients with locally advanced mid/low rectal cancer (cT3-4N0M0 or
cTanyN+M0) who undergo NCRT.
After giving fully informed consent, the prospective participants will undergo the classical
'NCRT + radical surgery + ACT' comprehensive treatment. Serial analysis of ctDNA will be
performed at specific time points including pre-NCRT, post-NCRT, postoperative week 1,
post-ACT, postoperative year 1, 2, and 3. The next-generation sequencing of surgical
specimens will be performed as well. Participants will be observed and examined during the
entire course of treatment and the follow-up period. The pathological results of the surgical
specimen and the 3 year disease free survival (3y-DFS) will be the main end-points.