The Effects Of Different Activity Of¹²⁵I Seeds Nterstitial Brachytherapy On Human Gastric Subcutaneous Arcinoma Of Nude Mice

Gastric cancer is a common malignant tumor in digestive tract. Operationis internationally recognized as the preferred method of treatment of gastriccancer. But most patients’s symptoms appeared ago has been localizedmetastases or peripheral tissue organ metastases, operation to radicalcombined with chemotherapy in treating gastric cancer, and there was a70%recurrence rate[1]. Local recurrence is the main cause of gastric cancertreatment failure. According to the literature[2,3]reported by autopsy found80%cause of cancer deaths in patients with residual or recurrence tumorlocalized in the region of. On postopevrtive recurrent of gastric cancer andadvanced gastric cancer, bowel obstruction, jaundice, anemia, weight loss orcachexia, clinically is still lack of life. Retroperitonsal lymph node metastasisdue to anatomic site of speration, easy removal, serious causes the waist,abdominal pain, affect appetite and rest and even lead to death. Althoughearly radiotherapy in gastric cancer intraperitoneal application have beenreported, but surrounding normal tissues such as the normal gastric tissue,intestine and can not tolerate radiotherapy dose, and gastric cancerradiotherapy>55Gy,30%-40%patients appeared complications afterradiotherapy[4], therefore, at present, the treatment of tumor radiotherapy dosenot actually tumor radical dose, but the tumor surrounding normal tissuemaximum tolerated dose. Eeternal radiotherapy for palliative radiotherapy intreatment of gastric cancer needs repeated treatment, due to repeatedchemotherapy side effects, especially in patients with poor general condition,difficult to tolerate.¹²⁵I seeds interstitial implantation treatment belongs to one ofbrachytherapy, for nearly a hundred years of history, currently at home and abroad has been widely used in solid tumor comprehensive treatment[5].Brachytherapy in treatment of tumor is the radioactive seeds implantationwithin the tumor or tumor infiltration of the tissue by the particle source, acontinuous low energy gamma rays, destroy tumor cells and fracture og DNAdouble strand, leading to tumor cells lose their proliferative capacity[6], andthe normal tissue without injury or minor injury[7]. Effect of¹²⁵I seedsimplantation for many kinds of factors, such as the activity, with activitydecreased, dose rate decreases exponentially, we can say the activity thataffects radioactivity¹²⁵I seeds is one of the key factors of efficacy andcomplications. At present, in the process of treatment of gastric cancer is less,therefore, how to select of the activity of radioactive¹²⁵I seeds on tumor cellsto killer and what are their efficacy and complications respectively in theclinical application of how are the problems to be solved.Through the observation of different activity of¹²⁵I seeds in gastriccancer and complications, compared with15⁽th(,30⁽th(day: high activity groups,low activity groups and the control group in the nude, nude body weight,survival rate of tumor inhibition rate, histopathological changes and the localskin reactions, for gastric cancer line particle implantation in the treatment ofselect¹²⁵I seeds activity and provide experimental basis.Objective: To explore the same matched peripheral dose of differentactivity of¹²⁵I seeds interstitial brachytherapy on human gatric carcinomaxenografts in nude mice killing effect andtissue injury.Methods: Animal model simulating human gastric carcinoma of42wereestablished by subcutaneous implantation into nude mice. Mice wererandomly divided into treated groups and the control group. The treatedgroups by implantation of seeds activity is divided into high-activity group（33.3MBq×1） and low-activity group （16.65MBq×2）, matched peripheraldose were100Gy. The control group （0MBq×2）. Each of groups was7nudemice. On15⁽th(,30⁽th(day after the¹²⁵I seeds implantation: comparison ofsurvival ratio, body weight of the nude mice, tumor inhibition rate （based on average tumor volume calculation）, histopathologic response and regionalskin reaction.Results：On15^th,30^thday①The survival ratio rate in control group andtreated groups were100%and100%, respectively.②The body weight ofnude mice: There was no statistically significant difference in the body weightamong the groups after¹²⁵I seeds implantation)P>0.05).③The average tumorvolume: there was statistically significant difference in average tumor volumefounded between the treated groups and the control group after15^th,30^thday)P<0.05), and there was no statistically significant difference in averagetumor volume founded between the treated groups and the control group after15^th,30^thday)P<0.05), and there was no statistically significant difference inaverage tumor volume founded within the treated groups. In all treatedgroups, the tumor volume inhibitory rates were66.85%,78.24%)15^thday)and82.5%,93.83%)30^thday), respectively.④Histopathologic response:on15^thand30^thday, there was statistically significant difference between thetreated group and the control group)P<0.05). There was statisticallysignificant difference in histopathologic response founded between the treatedgroups and the control group after15^th,30^thday)P<0.05), and there was nostatistically significant difference in histopathologic response founded withinthe treated groups.⑤Local cutireaction: there was statistically significantdifference between the treated groups and the control group)P<0.05), therewas statistically significant difference in local cutireaction founded betweenthe high activity group and the control group after15^th,30^thday)P<0.05), andthere was no statistically significant difference in local cutireaction foundedbetween the low activity group and the control group after15^th,30^thday)P>0.05), there was no statistically significant difference in localcutireaction founded within the treated group after15^thand30^thday)P>0.05).Conclusions:1．Radioactive¹²⁵I seeds implantation in the treatment ofgastric carcinoma transplanted subcutaneously in nude mice effectively. 2．In the peripheral dose in the same condition, high, low activity groups hadno significant difference in treatment, as the particle activity increases,increase radioactive injury.