局部晚期宫颈癌腔内联合自由式插植近距离治疗剂量分布研究

Dosimetric distribution study of combined intracavitary/free interstitial brachytherapy in locally advanced cervical cancer

目的比较局部晚期宫颈癌(ⅡB期体外照射后局部病灶残留≥5 cm)腔内联合自由式组织间插植(IC/IS)治疗及三维腔内治疗[IC(3D)]剂量分布之间的差异。方法选取局部晚期宫颈癌(ⅡB期)经体外放射治疗(EBRT)50.4 Gy/28f后肿瘤消退不明显、局部病灶≥5 cm的患者47例,分别采用IC(3D)(IC组,n=20)即宫腔管加卵圆体和宫腔管加插植针(IC/IS组,n=27)两种方式进行植入,行CT扫描、靶区勾画[宫颈癌的高危临床靶体积(HR-CTV)、直肠、膀胱及乙状结肠],计划设计采用模拟退火逆向优化(IPSA)方式,比较腔内治疗IC及腔内联合组织间插植治疗IC/IS之间剂量学差异。结果 IC/IS组HR-CTV的D90[(6.34±0.18)Gy vs(5.08±0.54)Gy]、D100[(4.30±0.37)vs(3.01±0.48)Gy]高于IC组,差异有统计学意义(P<0.01);IC/IS组HR-CTV的V100[(93.64±1.80)%vs(80.27±5.69)%]明显优于IC组,差异有统计学意义(P<0.01);而HR-CTV的V150及V200两组比较差异无统计学意义(P>0.05);IC/IS组膀胱、直肠、乙状结肠D2cc受量与IC组比较差异无统计学意义(P>0.05)。结论局部晚期宫颈癌(ⅡB期外照射后局部病灶残留≥5 cm)采用IC(3D)治疗虽可以保证正常组织达到剂量限制要求,但容易导致HR-CTV剂量不足;采用IC/IS治疗方式,不仅可以满足正常组织的剂量限制要求,而且可以满足HR-CTV的D90受量、得到更好的靶区适形度。

Objective To compare the difference of dosimetric distribution between combined intracavitary /free interstitial ( IC /IS) brachytherapy and three-dimensional intracavitary therapy [IC( 3D)] in locally advanced cervical cancer ( local lesion residual ≥5 cm after external irradiation in stage ⅡB).Methods A total of 47 patients with locally advanced cervical cancer ( stage IIB) who underwent external beam radiation therapy( EBRT) 50.4 Gy /28f with no obvious tumor regression and local lesions ≥5 cm were selected and were using uterine tube with oval body implant ( IC group, n = 20) and uterine tube with insertion needle implant ( IC /IS group,n = 27),CT scaned,target area delineation [high risk clinical target volume of cervical cancer ( HR-CTV),rectal,bladder,and sigmoid colon],the planned design used inverse simulated annealing optimization ( IPSA) and compared the dosimetric differences between IC and IC /IS.Results D90 [( 6.34 ± 0.18) Gy vs ( 5.08 ± 0.54) Gy] and D100 [( 4.30 ± 0.37) Gy vs ( 3.01 ± 0.48) Gy] of HR-CTV in IC /IS group were higher than that of IC group, and the differences were statistically significant ( P < 0.01).V100 [( 93.64 ± 1.80)% vs ( 80.27 ± 5.69)%] of HR-CTV in IC /IS group was significantly high than that of IC group,the difference was statistically significant ( P < 0.01);There was no significant difference in V150 and V200 of HR-CTV between the two groups ( P > 0.05).There was no significant difference in the dose of bladder,rectum and sigmoid D2cc between the IC /IS group and the IC group ( P > 0.05).Conclusions In patients with locally advanced cervical cancer ( residual lesions ≥5 cm after external exposure in stage IIB),IC ( 3D) treatment can ensure he dose limit requirements of normal tissues,but it is easy to cause HR-CTV dose deficiency;IC/IS treatment not only can meet the dose limit requirements of normal tissues, but also can meet the D 90 dose of HR-CTV and get better target area conformity.