| Objective: To study the therapeutic effect of interstitial brachytherapy by 125I seeds with the same activity but different distribution in gastric carcinoma nude mice.Methods: 70 nude mice models stimulating human gastric carcinoma were established by subcutaneous implantation of cultured BGC-823 cell lines into nude mice, 64 of which were chosen. Mice were randomly divided into treated group and control group. The treated group is implanted 125I seeds with the activity of 33.3MBq, all of them are divided into high activity group (33.30 MBq×1), moderate activity group (16.65 MBq×2) and low activity group (11.10 MBq×3), according to the activity and distribution of single seed, whereas in control group, the dummy seeds were implanted. Based on time of the observation, all groups are divided into 15-day and 30-day groups. Measure the nude mice volume and tumor weight once in three days, calculate the tumor volume and draw a weight growth curve of nude mice and tumor volume growth curve. At the 15th and 30th day, the tumor was cut off. The survival rate and weight of nude mice, the volume inhibitory rate, tumor regression and regional skin reaction in each group were compared, The pathological complete response and regional skin reactions are evaluated according to rectal cancer regression grade (RCRG) and the Radiation Therapy Oncology (RTOG) grade respectively. Analysis of variance and Kruskal-Wallis H test were employed to deal with the experimental data respectively.Results: Each group had no nude mice death, the survival rate was 100%.The weight of nude mice in each group has no significant difference (F=1.42, P>0.05); It showed a slight increase after seed is implanted. The growth curve of tumor volume in each treated group declined rapidly with time, while the growth curve in the control group rose rapidly. After 125I seeds implantation for15 days and 30 days, moderate and low activity group and the control group concentrated to the centre in varying degrees, high activity group is still in the regional centre. The volume inhibitory rate of 15-day and 30-day groups in the treated group were 66.62%, 77.84%, 76.23% and 92.47%, 97.15%, 89.01% respectively. There are significant differences between 15-day or 30-day treated group and control groups in average volume of nude mice (P<0.05), there are significant differences between high activity group and moderate activity group, low activity group of 15-day group (t=3.15, 2.69,P<0.05), between moderate activity group and low activity group of 30-day group (t=2.31, P<0.05). While no significant differences in other groups (P>0.05). The pathological evaluation: tumor cells surrounding 125I seeds in each 15-day and 30-day treated group appeared degeneration and necrosis in different degrees. At the 15th day, 8 nude mice in treated group were RCRG3 , 1 and 7 in high activity group were RCRG1 and RCRG2 respectively; 3 and 5 in moderate activity group were RCRG1 and RCRG2 respectively; 3 was RCRG1. 4 was RCRG2 and 1 was RCRG3 in low activity group. There were significant differences between each group(H=19.46, P<0.05); Rectal cancer regression grade (RCRG) 1 was seen in 30-day high activity group and moderate activity group; In low activity group 3 was RCRG3, 4 was RCRG2,1 was RCRG1.There were significant differences between each group(H=23.50,P<0.05).7 nude mice in high activity group appear RTOG1~2 radio active hurt after 9~12 days with 125I seeds implantation, and no hurt in nude mice of the moderate and low activity groups. There were significant differences between each group(H=65.54,P<0.05)。Conclusions: In the process of interstitial brachytherapy, choosing and distributing single 125I seed can have a direct impact on the therapeutic effect and the degree of radioactive injury. |
PDF Full Text Request