老年宫颈癌盆腔放疗骨盆限量对骨髓抑制的影响

Effect of dosimetric constraints in pelvic radiotherapy on bone marrow suppression in patients with cervical cancer

摘要:

目的 探讨老年宫颈癌患者行盆腔容积旋转调强放疗(VMAT)时骨盆限量的剂量(体积)参数与急性骨髓抑制发生的相关性,为临床确定骨盆限量的剂量(体积)参数标准提供依据。方法 回顾性分析2016年1月至2020年1月青岛市中心医院住院的老年宫颈癌患者76例,国际妇产科联盟分期为ⅠB～ⅣA期,均接受VMAT治疗,根据放疗计划是否符合骨盆骨髓保护(骨盆V20≤70%,V30≤50%,Vx指骨盆接受≥xGy剂量的体积)分为骨髓保护组(n=35)和非骨髓保护组(n=41)。采用SPSS 22.0统计软件进行数据分析。根据数据类型,分别采用t检验、秩和检验和χ²检验进行组间比较。 结果 骨髓保护组白细胞2级及以上骨髓抑制发生率为68.6%(24/35),低于非骨髓保护组87.8%(36/41),差异有统计学意义(P=0.042)；骨髓保护组中性粒细胞2级及以上骨髓抑制发生率为45.7%(16/35),低于非骨髓保护组发生率70.7%(29/41),差异有统计学意义(P=0.028)；骨髓保护组靶区适形指数(0.835±0.059)、均匀指数(0.090±0.005),非骨髓保护组靶区适形指数(0.854±0.072)、均匀指数(0.086±0.005),差异均无统计学意义(均P＞0.05)。结论 骨盆限量V20≤70%、V30≤50%可明显降低老年宫颈癌患者盆腔放疗2级及以上骨髓抑制的发生,且骨盆限量未影响放疗靶区剂量分布的适形度与均匀度,V20≤70%、V30≤50%可作为骨盆限量的剂量(体积)参数标准。

Abstract:

Objective To observe the correlation between the dosimetric constraints for pelvic bone marrow (PBM) and the occurrence of acute myelosuppression in elderly patients with cervical cancer undergoing pelvic volumetric modulated arc therapy (VMAT), and to provide reference for clinical determination of the dose/volume parameter standards of PBM sparing. Methods A retrospective analysis was performed on 76 elderly patients with cervical cancer who were treated in Qingdao Central Hospital from January 2016 to January 2020. They were classified into stage IB to IVA with International Federation of Gynecology and Obstetrics (FIGO) staging system and all received VMAT treatment. According to whether PBM sparing was performed (pelvic bone dose/volume parameters V20≤70%, V30≤50%, Vx refers to the volume of the pelvis receiving a dose ≥ xGy), they were divided into PBM sparing group (n=35) and non-PBM sparing group (n=41). SPSS statistics 22.0 was used for data analysis. Student′s t test, rank sum test or Chi-square test was used for comparison between groups depending on the data type. Results The incidence of myelosuppression with leukopenia≥grade 2 was significantly lower in the PBM sparing group (68.6%, 24/35) than the non-PBM sparing group (87.8%, 36/41, P=0.042). So was the incidence of neutropenia≥grade 2 in the 2 groups [45.7% (16/35) vs 70.7% (29/41), P=0.028]. There were no statistical differences in the conformity index (0.835±0.059 vs 0.854±0.072) and homogeneity index (0.090±0.005 vs 0.086±0.005) between the 2 groups (P>0.05). Conclusion PBM dosimetric constraints with V20≤70% and V30≤50% can significantly reduce the incidence of myelosuppression≥grade 2 in elderly patients with cervical cancer, and show no effect on the target volume dose conformity and homogeneity. V20≤70% and V30≤50% can be used as the dose/volume standards of PBM dosimetric constraints.