Modulated Electro-Hyperthermia in Combination With Multimodal Therapy for Locally Advanced Rectal Cancer

The goal of this clinical trial is to investigate if the addition of modulated electro-hyperthermia (mEHT) improves tumor down-staging and pathological response in adult patients (20 years and above) with locally advanced rectal adenocarcinoma (cT3N0M0 with high risk of recurrence, cT3N1-2M0, or cT4N0-2M0). The main questions it aims to answer are: * Does the addition of mEHT to the Total Neoadjuvant Therapy (TNT) regimen significantly increase the rate of tumor down-staging (ypT and ypN) compared to TNT alone? * Does the combination therapy improve the pathological complete response (pCR) rate and long-term outcomes (such as disease-free survival) compared to standard TNT? Researchers will compare participants randomized to receive Total Neoadjuvant Therapy (TNT) plus mEHT using the Oncotherm EHY-2030 device to participants receiving TNT alone to see if the adjunctive mEHT therapy enhances tumor regression and improves patient prognosis. Participants will be randomized (1:1) into one of the two groups and will undergo the following regimen: * Receive standard TNT, which includes 5-6 weeks of chemoradiotherapy (CRT) followed by 4-6 months of neoadjuvant chemotherapy. * Patients in the experimental group will receive mEHT twice a week during the CRT period.

Sex

All

Minimum age

20 Years

Inclusion Criteria:

1. Age: 20 years and above
2. Gender: Not restricted
3. Initial pathological diagnosis of adenocarcinoma of the rectum
4. Expected survival ≥ six months
5. Clinical staging of cT3N0 with high recurrence risk or cT3N1-2 or cT4N0-2 rectal cancer, requiring neoadjuvant therapy, without distant metastasis; must meet the following tumor definitions \[staging system according to the 8th edition of the AJCC staging manual\]:

   1. cT3: Tumor invades through the muscularis propria into pericolorectal tissues
   2. cT4a: Tumor invades through the visceral peritoneum (including gross perforation of the bowel through tumor and continuous invasion of tumor through areas of inflammation to the surface of the visceral peritoneum)
   3. cT4b: Tumor directly invades or adheres to adjacent organs or structures \*High recurrence risk factors: cT3 tumor ≤ 5 cm from the anal verge or MRI showing circumferential resection margin (CRM) \< 0.2 cm; cT4 tumor or cN2, presence of MRI showing extramural vascular invasion.

7\. ECOG performance status: 0 - 2 8. Healthy condition suitable for standard treatment, including 25 to 30 fractions of long-course radiotherapy and concurrent chemotherapy (capecitabine or fluorouracil) and subsequent 4- to 6-month chemotherapy, including modified FOLFOX-6 or CAPEOX 9. Willingness to participate in the clinical trial and signed the informed consent form for the protocol.

Exclusion Criteria:

* (e) Active infection or severe underlying disease making the patient unsuitable for the trial treatments
* Known HIV infection
* Untreated thyroid disease
* Active Crohn's disease or ulcerative colitis
* Other systemic autoimmune diseases 9. History of any physical or mental disorder resulting the patient unable to understand or comply with trial requirements, or diminished social communication ability, or unable to provide informed consent 10. Known allergic reaction to trial medications 11. Pregnant or breastfeeding women 12. Substance or alcohol dependence within six months before screening 13. Inability to comply with treatment, assessments, or follow-up

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