Long-Term Feasibility of 13.56 MHz Modulated Electro-Hyperthermia-Based Preoperative Thermoradiochemotherapy in Locally Advanced Rectal Cancer

Survival probability

Survival probability

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Summary

This study evaluated the effect of 13.56 MHz modulated electro-hyperthermia (mEHT) boost in neoadjuvant treatment for patients with rectal cancer. The results suggest, mEHT was feasible considering long-term survival.

Patients characteristics

60 patients with median age of 59 (range, 33–83) years, and they were predominantly male (n = 3
45, 75%). The clinical tumor volume had a median of 52.7 (range, 22.4–233.1) cm , patients with
cT3-4 or cN positive rectal cancer faithfully underwent preoperative radiochemotherapy with concomitant mEHT boost. All patients had a general condition of ECOG performance status ≤2.

Treatment

Three- or four-field linear accelerator-based 6–15 MV X-rays from three-dimensional planning were delivered to the whole pelvis area including the rectal tumor, mesorectum, and internal iliac/presacral lymph node chain up to the sacral promontory level in 2 Gy daily fractions up to a total dose of 40 Gy.
Intravenous 5-fluorouracil (400 mg/m2/day at the 1st and 5th weeks from the start of radiotherapy) or oral capecitabine (825 mg/m2 based on the virtual period of the conventional 28-fraction radiation schedule) was administered concomitantly.
In addition to chemoradiation, eight sessions of mEHT were combined twice weekly during the radiotherapy period using 13.56 MHz capacitive coupled device (EHY2000). Treatment was performed such that a 30 cm- diameter electrode included the entire treatment area based on the center of the irradiation site while the patient was in a supine position. Treatment duration per session was 60 min, and the interval between mEHT and radiotherapy on the same day was <1 hour. The power to be applied was 140 W; only for the first session, a gradual power increase method (starting at 100 W to increase in 20 W per 20 min) was used in consideration of the patient’s adaptation status.

Results

The median follow-up period was 58 (6–85) months. Total/near total tumor regression was observed in 20 patients (33.3%), including nine cases of complete response.
Toxicity
All acute toxicity occurred within grade 2. As for late toxicity, there were no >grade 2 events other than grade 3 gastrointestinal toxicity in four cases. Among the analyzed patients, mEHT-related toxicity was mild in all but one grade 2 case.
SurvivalThe 5-year overall survival (OS) is 94%, disease-free survival (DFS) is 77.1%, LRRFS is 96.4% and DMFS rates were78.7%.

Conclusion

A non-inferior effect of 40 Gy radiation plus mEHT combination was substantiated in the long- term survival of patients. In a slightly low-dose radiation platform, less thermotoxic mEHT can be considered to aid in rectal cancer treatment.

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Scientific article publishing date: 3/1/2022

Immucura identifier BSC22_375EN

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