Local low-frequency magnetic field as radio-modificator of preoperative radiotherapy in rectal cancer
Radiation therapy for rectal cancer is effective and scientifically grounded method of antitumor action that integrates achievements of experimental and clinical oncology, radiobiology, physics and a range of opportunities of gamma-therapeutic equipment. But the opportunity of radiotherapy for rectal cancer is limited by the low tolerance of surrounding organs and tissues before exposure. It is also limited the risk of inducing adverse reactions by the body in general. This fact is the basis for searching ways and remedies that would help to increase the radiosensitivity of the rectum tumor. The aim – an investigation of effective radiomodification by the local low-frequency magnetic field in the neoadjuvant therapy for rectum cancer. An investigation included 52 patients aged 41 - 80 years old (62,8±8,6): 27 (51,9%) men and 25 (48,1%) women. The design of study is to conduct the searching of proliferate activity (Ki-67) in adenocarcinoma of the rectum and further neoadjuvant radiation therapy (NRT), total focal dose (TFD) 20-25 g (4-5 sessions to 5 g) using physical radio modifier (local low-frequency magnetic field). Later it was second study of proliferation activity (Ki-67) in adenocarcinomas and also surgery. Established that the expression of Ki-67 in the adenocarcinomas of the rectum to NRT and radiomodification by the local low-frequency magnetic field (RLLMF) was 15,5±5,9% (p<0,05). Thus expression of Ki-67 in adenocarcinomas of the rectum decreased by 9,8%. An index Ki-67 to NRT and RLLMF of the patients that have the degree differentiation of adenocarcinomas of the rectum G2 (n=43) was 24,8±9,4%. The index of the patients that have the degree differentiation G3 (n=9) to NRT and RLLMF was 27,6±9,4% (p>0,05). After NRT and RLLMF the patients of G2 (n=48) have Ki-67 of 15,0±5,5%. But the patients of G3 (n=4) have Ki-67 of 22,2±8,4% (p=0,01). There was a significant difference in reducing the percentage of proliferation activity in subgroups of patients with moderately differentiated (G2) and low-differentiated adenocarcinoma (G3) after NRT and RLLMF. Ki-67 index (n=43) G2 after NRT and RLLMF decreased by 9,3% but index Ki-67 (n+4) G3 after NRT and RLLMF decreased by 5,4%. However it should be noted that degree differentiation of n=5 from G3 has changed to G2. It was noted the moderate correlation of proliferation index from the expression level of Ki-67 till the treatment beginning and the expression of Ki-67 against a background of NRT and RLLMF: r=0,6; p<0,05. Index of proliferation activity in the adenocarcinomas of the rectum of the old age and elderly patients (n=19) was almost equal 24,9±8,0% and 26,0±10,8%. After the end of NRT and RLLMF the average value of Ki-67 in the adenocarcinomas of the rectum of age subgroups was 16,0±5,8% (n=33) and 14,3±6,1% (n=19). Proliferation index of adenocarcinomas of the middle-aged patients decreased by 11,7% but it was by 8,9% (p<0,05) of the old age and elderly patients. So according to research local low-frequency magnetic field against a background of radiation therapy is an effective factor that contributes to the morphological and immunohistochemical regression of adenocarcinoma of the rectum.
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