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The cisplatin-based concurrent chemoradiotherapy (CCRT) has been accepted as a standard treatment for most locally advanced cervical cancer. Compared with radiation therapy alone, CCRT can increase tumor control and survival rates, whereas it also can increase the incidence of acute hematological toxicity, which results in the treatment interruption or delay, and may even affect clinical efficacy and prognosis of patients. Therefore, how to reduce the incidence and severity of acute hematological toxicity induced by CCRT is a hot spot of clinical research. Previous studies have demonstrated that the occurrence of hematological toxicity is associated with the volume and dose of irradiated pelvic bone marrow. With the development of modern radiotherapy technology, precise radiotherapy technologies, such as intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT), not only guaranteed the enough dose for tumor, but also realized the protection of normal tissues. This article will focus on the feasibility of bone marrow sparing during CCRT for cervical cancer, and summarize the research progress in recent years.
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Concurrent chemoradiotherapy can improve the survival rate in patients with advanced pelvic tumors.However,it also increases the incidence of hematologic toxicity and other adverse events.Patients cannot tolerate these adverse events and discontinue the therapy.Pelvic bone marrow-sparing intensity-modulated radiotherapy (PBMS-IMRT) possesses obvious advantages in reducing the radiation dose and volume of the pelvic bone marrow.In this article,comparison between PBMS-IMRT and other irradiation therapies,correlation between dosimetric parameters and hematologic toxicity and imaging methods with precise delineation of the active bone marrow were reviewed.
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Objective To analyze the relationship between the dose volume of bone marrow and acute hematologic toxicity in craniospinal irradiation (CSI),and preliminarily explore the dosimetric differences in bone marrow between helical tomotherapy (HT) and volumetric modulated arc therapy (VMAT).Methods Clinical data and HT plans of twenty patients treated with CSI in the First Affiliated Hospital of Kunming Medical University were collected,and the HT plans were transferred back to the MIM system.The skull,mandible,clavicle,sternum,scapula,ribs,vertebrae and pelvis were successively delineated on the CT images and then the V2,V5,V10,V15,V20,V25,V30,V35,Dmax Dmean of each aforementioned bone and total bone were read on DVH images.The correlation between those indexes and the incidence of ≥ grade Ⅱ hematologic toxicity was subsequently analyzed.The images of 6 patients were selected and transferred to Monaco TPS and VMAT plans were completed.The dosimetric differences of those indexes were statistically compared between HT and VMAT.Statistical analyses were performed by using Spearman correlation analysis and Wilcoxon symbol rank-sum test.Results The incidence of ≥ grade Ⅱ leukopenia was positively correlated with the V25 of pelvis and the V5 of total bones (P =0.038);the risk of ≥ grade Ⅱ thrombocytopenia was positive associated with the V20 of pelvis (P=0.041);the incidence of ≥grade Ⅱ neutropenia was positively correlated with the V10 of vertebrae (P=O.036).There was no dosimetric difference of dose volume of vertebral and pelvis between HT and VMAT plans (P＞ 0.05).Conclusions There is a positive correlation between ≥ grade Ⅱ leukopenia and the V25 of pelvis and the V5 of total bones.The V20 of pelvis shows a positive correlation with ≥ grade Ⅱ thrombocytopenia.A positive correlation is found between ≥ grade Ⅱ neutropenia and the V10 of vertebrae.The indices of vertebral and pelvis between HT and VMAT plans show no significant differences.
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Objective To observe the therapeutic effects and toxicities of bone marrow-sparing intensity-modulated radiation therapy (BMS-IMRT) for postoperative cervical cancer.Methods From January 2011 to June 2012,totally 70 postoperative patients with cervical cancer were divided into BMS-IMRT group with 34 cases and IMRT group with 36 cases randomly.External whole pelvic intensitymodulated irradiation combined with chemotherapy was carried out for all patients.The planning target volume received a dose of 45 Gy/25 fractions in all patients.Delineation of the pelvis and limitation dose were carried out in BMS-IMRT group:the pelvis V30 ≤ 50％.All cases received chemotherapy with cisplatin (40 mg/m2) once a week concurrently with radiotherapy.Results Treatment was completed in 67 patients,as the other 3 patients stopped chemotherapy because of myelosuppression.There was no statistically significant differences between two groups for the 2-year local control survival(LCS)and overall survival(OS),alimentary tract toxicity and urinary toxicity.IMRT group had more serious hematologic toxicity than BMS-IMRT group,with statistically significant difference (x2 =14.355,P ＜ 0.05).Conclusions The postoperative cervical cancer patients with poor prognostic factors who undergo concurrent chemoradiotherapy,IMRT group has more serious hematologic toxicity than BMS-IMRT group.The short-term effect and other toxicities reaction are similar between two groups.
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Objective:To compare bone marrow-sparing intensity-modulated radiotherapy(BMS-IMRT)with conventional (four-field box[3DCRT]and anteroposterior-posteroanterior[CRT])techniques in the treatment of cervical cancer.Methods:For a cohort of 10 patients,BMS-IMRT,3DCRT and CRT planning were designed.The prescribed dose was 45Gy/1.8Gy/25f,95%of the planning target volume received this dose.Doses were computed with a commercially available TPS.Plans were compared according to dose-volume histogram (DVH)analysis in terms of PTV homogeneity and conformity indices(HI and CI)as well as OARs dose and volume parameters.Results:BMS-IMRT had an advantages over 3DCRT and CRT in terms of CI,but inferior to the latter two for HI.BMS-IMRT was superior to 3DCRT in reducing the dose to PBM,small bowel,bladder and rectum.Compared with CRT,BMS-IMRT reduced the volume irradiated to the doses from 30Gy to 40Gy,but increased the volume irradiated to the low doses from 5Gy to 20Gy.In addition,BMS-IMRT reduced the volume of small bowel,bladder,rectum at nearly all dose levels.Conclusion:BMS-IMRT reduced irradiation of PBM compared with 3DCRT technique.Compared with CRT technique,BMS-IMRT reduced the volume of PBM irradiated to high doses.Therefore,for patients with cervical cancer after hysterectomy,BMS-IMRT might reduce acute hematologic toxicity(HT)compared with conventional techniques.