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ORIGINAL ARTICLE
Year : 2021  |  Volume : 17  |  Issue : 3  |  Page : 688-694

Comparison of three-dimensional-printed template-guided and traditional implantation of 125I seeds for gynecological tumors: A dosimetric and efficacy study


1 Department of Oncology, Hebei Medical University, No.361 East Zhongshan Road, Shijiazhuang; Department of Surgery, Maternal and Child Health Hospital of Shijiazhuang, Hebei, China
2 Department of Oncology, Hebei General Hospital, Shijiazhuang, Hebei, China
3 Department of Oncology, Hebei Medical University, No.361 East Zhongshan Road, Shijiazhuang, Hebei, China
4 Department of Oncology, Hebei Medical University, No.361 East Zhongshan Road; Department of Oncology, Hebei General Hospital, Shijiazhuang, Hebei, China

Date of Submission24-Oct-2020
Date of Decision25-Dec-2020
Date of Acceptance01-Apr-2021
Date of Web Publication9-Jul-2021

Correspondence Address:
Juan Wang
Department of Oncology, Heibei Medical University, No. 361 East Zhongshan Road, Shijiazhuang, Hebei; Department of Oncology, Hebei General Hospital, Shijiazhuang, Hebei
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jcrt.JCRT_1565_20

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 > Abstract 


Objective: The objective of the study was to compare the dose parameter and clinical efficacy of three-dimensional-printed template (3D-PT)-guided and traditional 125I seed implantation in treatment of gynecological tumors.
Materials and Methods: A total of 28 patients with gynecological tumors treated with radioactive seed implantation in Hebei General Hospital from January 2016 to December 2018 were retrospectively analyzed. Twelve patients (template group) were guided by 3D-PT and the remaining 16 patients (traditional group) were guided by computed tomography (CT) with traditional technique. Preoperative treatment plan (preplan) was completed through a treatment planning system. In the template group, 3D-PT was printed according to preplan and seeds were implanted under the guidance of 3D-PT and CT. In the traditional group, seeds were implanted under the guidance of single CT directly according to the preplan. Postoperative verification plan (post-plan) was completed. Dose–volume histogram (DVH) was calculated and D80, D90, V90, V100, and V150 were obtained according to DVH. Then, deviation of the dosimetric parameters D80, D90, V90, V100, and V150 between the preplan and postplan were compared within the two groups. The difference and percentage of difference of the above dosimetric parameters between the preplan and postplan within the two groups were calculated using the formula Xd = Xpost-plan– Xpre-plan, and Xd% = (Xpost-plan– Xpre-plan)/Xpre-plan × 100%. Doses were calculated to determine whether the differences there were statistically significant. Efficacy evaluation was completed according to RECISIT 1.1. Local control rate and effective rate of 2-months postplan were compared between the two groups. Survival analysis was completed by the Kaplan–Meier method. The patients were followed up for 12 months, and their survival rate was calculated and compared.
Results: There was no significant difference between the two groups for all the parameters, except for D80 of the preplan and postplan in the traditional group (P = 0.000). All the differences and percentage of difference were calculated and it was found that the Xd difference of D80 (P = 0.035), D90 (P = 0.023), V90 (P = 0.047), V100 (P = 0.032), and V150 (P = 0.031), as well as the Xd% difference of D80 (P = 0.032), D90 (P = 0.034), V90 (P = 0.042), V100 (P = 0.036), and V150 (P = 0.044) of the two groups was statistically significant, thus indicating that the dosimetric parameter fluctuation in the template group was more stable. The result of the curative effect after 2 months were as follows: the local control rate and effective rate of the template group were 100% (12/12) and 83.3% (10/12), while those of the traditional group were 100% (16/16) and 81.2% (13/16). There was no statistically significant difference in the curative effect between the two groups. After 6–27 months (median = 12 months) of follow-up, the median survival time of the template group and traditional group were 17 (10–23) and 16 (11–20) months, respectively, and the 1-year overall survival rate was 63% and 79% (P = 0.111), respectively, with no statistically significant difference observed.
Conclusion: 3D-PT-guided 125I seed implantation is safe and effective in the treatment of gynecological tumors.

Keywords: Brachytherapy, gynecological tumors, iodine isotopes, seed implantation, three-dimensional-printed template


How to cite this article:
Kang W, Zhang H, Liang Y, Chen E, Zhao J, Gao Z, Wang J. Comparison of three-dimensional-printed template-guided and traditional implantation of 125I seeds for gynecological tumors: A dosimetric and efficacy study. J Can Res Ther 2021;17:688-94

How to cite this URL:
Kang W, Zhang H, Liang Y, Chen E, Zhao J, Gao Z, Wang J. Comparison of three-dimensional-printed template-guided and traditional implantation of 125I seeds for gynecological tumors: A dosimetric and efficacy study. J Can Res Ther [serial online] 2021 [cited 2021 Jul 29];17:688-94. Available from: https://www.cancerjournal.net/text.asp?2021/17/3/688/321012




 > Introduction Top


Gynecological tumors mainly include the uterus, vagina, and ovarian malignant tumor. All these tumors are given priority for comprehensive treatment including surgery, radiotherapy, and chemotherapy. The anatomical relationship of gynecological tumor is complicated, especially for metastasis lymph nodes, which surrounds the tumor, retroperitoneal vessels, nerve, and spinal cord. Surgery is a difficult modality for the complete treatment of gynecological tumor; besides, it may lead to high complications and the effect is not ideal. In literature, it was reported that the 1-year survival rate of patients with gynecological tumor is 15%–27%, while the 5-year survival rate is 3.2%–13%.[1],[2] Radiotherapy is an important treatment method and the median survival time of patients with gynecological tumor recurrence and metastasis treated by external radiotherapy alone was only 8 months.[3] However, the incidence of adverse reactions is 89.5%, among which 12.5% of patients develop late reactions.[4] Therefore, external irradiation combined with intracavitary brachytherapy is widely used, especially the high-dose intracavitary brachytherapy with 192I radioactive source. The local control rate of intracavity brachytherapy for small gynecological tumors is up to 75%–95%.[5] However, it is difficult to insert the applicator under poor anatomical conditions (such as vaginal stenosis) or retroperitoneal lymph node metastasis if the target volume of intracavitary radiotherapy is not fully covered, prescribed dose (PD) cannot cover all clinical target volume, and local control rate is low.[6],[7] The American Association for Brachytherapy and European scholars recommend interstitial implantation therapy, which can make up for the deficiency of intraluminal radiotherapy, in order to better cover the target area[8] and perform accurate dose irradiation on the target area. If the tumor is too high and difficult to implant, radioactive seed implantation can be used.[9]

Radioactive 125I seed implantation has been mostly used in the treatment of recurrent and metastatic gynecological tumors, which provides a new direction for the treatment of gynecological tumors, thus achieving a good efficacy.[10] However, currently, there is no standard implanting method, apart from freehand implantation, which requires multiple computed tomography (CT) scans and repeated adjustment of needle path. The operation time is long; the preoperative plan is not consistent with the intraoperative implantation and it induces a low control rate. Zhang et al.[11] compared the difference between three-dimensional-printed template (3D-PT)-guided 125I seed implantation and traditional implantation and concluded that the postimplantation dose guided by 3D-PT was inconsistent with the preoperative plan dose, which could provide a scientific basis for precise implantation of seeds according to the preoperative plan. The 3D-PT can insert the needle at any angle at the same time, effectively avoiding the puncture of blood vessels and bones. 3D-PT is more consistent and can meet the requirements of dosimetry. The dose distribution of 3D-PT implantation is more conformal to the tumor, with small error. 3D-printed template-guided 125I seed implantation is safe and effective in the treatment of gynecological tumors.


 > Materials and Methods Top


Ethics statement

All patients including in this study underwent 125I seed implantation at our hospital. Ethics approval was obtained from the Ethical Committee of the Hebei General Hospital and all patients signed an informed consent.

Study population

A retrospective analysis of the medical records of patients with gynecological tumors in our hospital between January 2016 and December 2018 was performed. A total of 28 patients met the inclusion criteria (age range = 34–70 years). Among these patients, 16 cases were cervical cancer, 5 cases were ovarian cancer, 6 cases were endometrial cancer, and 1 case was vaginal cancer [Table 1]. There were 28 lesions in total. The patients were generally in good condition, without severe organ dysfunction. All patients had an ECOG <2. The primary tumor was pathologically proven malignant and without other distant metastases of vital organs. There were clinical lesions that can be evaluated. There was no obvious abnormality in routine blood tests, biochemistry examination, or coagulation function. The expected survival time was more than 6 months. They all signed informed consent and refused radiotherapy, chemotherapy, and other treatments. Some patients cannot tolerate radiation or chemotherapy. The exclusion criteria included patients with severe organ dysfunction, blood coagulation disorder, acute and chronic infection, mental disorder, and patients not appropriate for seed implantation determined by the surgeon.
Table 1: Clinical information of the two groups

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Therapeutic method

Preoperative plan and three-dimensional-template printing

One week before implantation, the patients were fixed in preset surgical position with vacuum cushion. A position line was drawn along the CT positioning laser line at the flat skin on upper edge of the tumor surface projection and 3–4 markers were pasted on the horizontal line at a distance of 3–4 cm. Then, enhanced CT scanning was performed with a slice thickness of 5 mm. Afterward, the CT DICOM data were transmitted to Prowess treatment planning system (TPS) (Panther Brachy version 5.0 TPS, Prowess Inc., Concord, CA, USA) to create Brachy Stereo–Seed preplan. In TPS, the target volume and organ at risk (OAR) were delineated carefully according to the CT images and seed activity was selected. Regarding the activity, when the tumor is near an OAR such as bowel, the activity is reduced to prevent intestinal damage, which is caused by the high activity particles. The application of high activity particles will produce high dose area when the target area is located in the groin, OARs are less, target area is not sensitive to radiation, and volume of the target area is larger. After comprehensive evaluation, the particles with higher activity are selected. The needle entry paths were designed according to the relationship between tumor and blood vessels, bones, and OARs. The needle passage layer interval was 5–10 mm [Figure 1]a. When the target and OAR dose reach the prescribed dose, the plan was committed and D90, V90, V100, V150, seed number, and dose–volume histogram (DVH) were generated. Finally, we ordered a definite amount of seeds needed and prepared. Meanwhile, TPS was applied to reconstruct the skin contour of CT images, needle passage coordinates, and the area to be printed [Figure 1]b. According to clinical requirements, size of the needle passage puncture hole was defined and the printing files were generated as output. The templates were printed by a sla600 type 3D printer (Unicorn 3DSL450M, Beijing Unicorn Science and Technology Ltd., Beijing, China). The 3D printed templates were disinfected and sterilized a day before the implantation.
Figure 1: (a) Preplan made by treatment planning system to determine the number, location of the radioactive implanted seeds, as well as the needles direction and depth. (b) Three-dimensional view of the reconstructed template, skin surface, needles, tumor, and organ at risk

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Seed activity measurement

A radioactivity meter (RM-905a well-type ionization chamber, National Institute of Metrology, Beijing, China) was used to measure the activity of radioactive 125I seeds (model 6711-99; activity, 0.3–0.7 m Ci; length, 4.5 mm; diameter, 0.8 mm; average energy, 27–35 keV; Beijing Zhibo Pharmaceutical Company, Beijing, China) before the operation. If activity error was <5%, all seeds would be blocked in the shell of the brachytherapy applicator for disinfection.

Brachytherapy operation

The patients were fixed with vacuum cushion in order to achieve the consistent position as preplan. The laser line of CT positioning was superimposed on the skin of the patients before implantation. In the freehand group, after disinfection, under local anesthesia, puncture was performed directly under the guidance of CT and seeds were implanted according to the preoperative plan. In the template group, after the disinfection of 3D-PT, the templates were fixed according to the body surface mark. Afterward, the position of the template was confirmed by CT scan, and needles were punctured though the preset needle path on the templates [Figure 2]. Another CT scan was performed after all the needles were punctured into the tumor [Figure 3]. If all the needles reach the right place in the tumor, the seeds were implanted according to the preoperative plan.
Figure 2: Photograph of the template in position on the patient and with the seed-loaded needles inserted to the planned depth

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Figure 3: Computed tomography scan during the implanting to confirm the needle positions

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Postoperative validation

Another CT scan with 5 mm interval was performed immediately after the seeds implantation process. After the image was transferred to TPS, the postplan was started. The target volume and OARs were delineated. All the seeds in the CT images were pick up. The postoperative isodose curve [Figure 4], DVH and other parameters were calculated.
Figure 4: Postplan made by treatment planning system and the isodose line distribution

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Therapeutic evaluation and side effects

The difference of D80, D90, V90, V100, and V150 between the two groups before and after implantation was compared. The formula Xd = Xpost-plan– Xpre-plan and Xd% = (Xpost-plan-Xpre-plan)/Xpre-plan × 100% were used to calculate the difference value and percentage of D80, D90, V90, V100, and V150 between the two groups and to determine whether the difference and percentage difference value of parameters between the two groups were statistically significant.

All patients who accepted radioactive seeds brachytherapy were followed up with CT at 1 and 2 months after implantation. The largest diameter of the tumor was measured and all tumors diameters were added up. According to Response Evaluation Criteria in Solid Tumors 1.1, tumor response in every patient was classified into four categories: complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD). CR implies complete disappearance of lesions disappeared, which was achieved at least 4 weeks. PR was reduction of target lesion length and diameter by at least 30% relative to baseline level for at least 4 weeks; SD was between PR and PD (the overall diameter of target lesion increasing by ≥20% relative to baseline or the emergence of new lesion. Effective rate = (CR + PR)/total number of cases × 100%; Local control rate = (CR + PR + SD)/total number of cases × 100%.

Statistical methods

SPSS Statistics for Windows, versions 22.0 (IBM Corp., Armonk, NY, USA) was used for the data analysis. Paired t-test was applied to analyze the statistical difference in D80, D90, V90, V100, and V150, as well as the difference and percentage difference value between the preplan and postplan of the two groups. Kaplan–Meier method was used to analyze the efficacy and survival rate. P < 0.05 was considered statistically significant.


 > Results Top


All the 12 patients in the template group and all the 16 patients in the traditional group were successfully operated. The mean values of D80 and D90 before and after operation in the two groups are shown in [Table 2].
Table 2: The mean values of D80 and D90 before and after operation in the two groups

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The mean values of V90, V100, and V150 in the two groups after operation are shown in [Table 3]. The difference and percentage difference of D80, D90, V90, V100, and V150 between the two groups before and after operation are shown in [Table 3].
Table 3: Statistical analysis of parameters of the two groups

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Postoperative CT re-examination was performed in the two groups after 2 months and compared with preoperative CT. Evaluation of 2 months after surgery was conducted according to the efficacy evaluation criteria. CR in the template group was 6 cases, PR was 4 cases, SD was 2 cases, effective rate was 83.3% (10/12), and local control rate was 100% (12/12). There were 10 cases of CR, 3 cases of PR, and 3 cases of SD in the traditional group. The 2-month effective rate was 81.2% (13/16) and the local control rate was 100% (16/16). There was no statistically significant difference between the local control rate and effective rate (χ2 = 1.44) [Table 4]. As for complications, one patient in the traditional group experienced hemorrhage of about 20 ml. Pain and fever occurred in both groups. Seeds migration occurred in some patients with recurrent central cervical cancer and seeds fell off from the vagina after implantation.
Table 4: Efficacy and complications of the two groups

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For the survival analysis, patients were followed up for 6–27 months and the median follow-up time was 12 months. The 1-year survival rate was 63% and 79%. The median survival time was 17 (10–23) months. Group 2: 16 (11–20) months. The 1-year survival was similar and the 2-year survival was better with the template group [Figure 5].
Figure 5: 1: Template group 2: Traditional group

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 > Discussion Top


Radioactive seed implantation has provided a new way for the treatment of gynecological tumors and has achieved good results. At present, the main seeds implantation method is the free-handed method, which has many shortcomings.[12],[13],[14],[15],[16],[17],[18] However, there are few reports on whether the application of 3D-PT can make up for these shortcomings and give full play to its advantages. Ang et al.[19],[20] reported that the accuracy of dose parameter was greatly improved when the 3D-PT were applied to abdominal tumors. In this study, there were no statistically significant differences in D90, postoperative V90, V100, and V150 between the template group and traditional group before and after surgery. Compared to tumors in thoracic and abdominal regions, gynecological tumors are greatly affected by anatomical structure such that it there is an uncertainty of the depth and path of needle inserted and that dissatisfaction of needle entry will still occur even if the 3D template is used and the needle passage needs to be adjusted again and that there is a little difference in the dosimetric parameters. However, the difference and difference percentage of D80, D90, V90, V100, and V150 in the template group were smaller and the data were more stable than that of the traditional group and the difference was statistically significant, indicating that, compared to the traditional group, the application of the template was advantageous. It is consistent with Zhang Hongtao's report.[21] We therefore opine that traditional implantation requires higher skill and experience and that the operation error incurred by different doctors is high and that the repeatability is low, which is not favorable to the quality control of seed implantation. In addition, the cooperation between physicists and operators is inadequate so that the preoperative plan cannot be well implemented during the operation process. The application of 3D-PT can make up for these errors, reduce the requirements on the operator's technical level, implement the preoperative plan more accurate, have good repeatability, simplify the process, and provide accurate dose, which is an important guarantee for quality control and treatment effect improvement. As the location of gynecological tumors varies in depth, the puncture route is uncertain, which would lead to the increase of 3D template application. During the intraoperative operation, the anatomical factors of the tumor should be taken into account and the intraoperative plan should be combined if necessary.

In terms of clinical efficacy, most of the patients underwent multi-line treatment and some of the patients were at the advanced age, so this study only evaluated the local control rate and effective rate 2 months after seed implantation in the two groups. Statistical analysis showed that there was no difference in the efficacy 2 months after seed implantation in the two groups. The reasons for the analysis may be as follows: First, the efficacy of seed implantation depends on the dosage. There was no statistically significant difference in D90 between the two groups; thus there was no statistically significant difference in efficacy between the two groups. Second, due to the influence of various factors, the small sample size of this study also had a certain impact on the experimental results. Third, the follow-up time was short in this study. Fourth, the traditional group applied intraoperative plans to ensure an accurate dose.

As for complications, one patient in the traditional group experienced hemorrhage of about 20 ml. The hemorrhage stopped after symptomatic treatment. The hemorrhagic spot was close to the puncture point. The reason for the hemorrhage might be that the microvessel pierced by puncture needles. Pain and fever occurred in both groups and transient postoperative pain was considered to be related to local tissue edema caused by the operation. Fever was considered to be related to the tumor absorption heat, stress response of patients, or some other unknown reasons. In this study, seeds migration occurred in some patients with recurrent central cervical cancer and seeds fell off from the vagina after implantation, resulting in the decrease of local dose. Furthermore, the tumor is more likely to spread along the vaginal wall; the tumor boundary is not easy to be determined and the peripheral dose drops rapidly, which would affect the dose distribution on target. Moreover, the vaginal wall is thin, which would increase the difficulty of operation. The above reasons may affect the efficacy of seed implantation in such patients. The data of complications in the template and traditional group were 13 and 20, respectively. There was no statistically significant difference in the incidence of complications between the two groups. However, it was judged that the safety of the 3D group was higher than that of the traditional group, based on the numerical results of complications, indicating that the application of 3D-PT reduced the incidence of complications compared to the traditional group. Multicenter large-scale randomized controlled trial is needed if statistical differences are to be obtained.

In this study, the median survival time of the two groups was 17 (10–23) and 16 (11–20) months and 1-year overall survival rate was 63% and 79%, respectively. The results were similar to the reports of Ang et al.,[22] and the efficacy reported in foreign studies were superior to this study. The patients in this study were those who had received radiotherapy or chemotherapy again after recurrence and all of them refused surgery or were unable to receive surgery. The patients that enrolled in foreign studies had better basic physical conditions and less early treatment. The median survival time was 17 (10–23) and 16 (11–20) months and the 1-year overall survival rate was 54.7% and 47.7%, respectively. Although there was no statistically significant difference, the template group was slightly better than the traditional group according to the data. This indicates that the treatment effect of the template group was significantly better than that of the traditional group; however, the survival time of patients in the template group was longer than those in the traditional group, but the difference was not statistically significant. Thus, more samples are needed for future studies if a significant difference is to be obtained.

To sum up, 125I seeds brachytherapy, which is guided by 3D-PT, is a feasible treatment modality for gynecological tumors. 3D-PT achieved accurate dose control and good repeatability, which is favorable to the promotion and application of 3D-printed technology. However, this study is a retrospective study and there are a little number of cases included in this study. In future, large-scale prospective randomized studies are needed to verify the clinical value of 3D-PT -assisted 125I seeds brachytherapy in gynecological tumors.

Acknowledgments

The authors would like to thanks Health and Family Planning Commission of Hebei province for supporting Juan Wang, which enabled her to perform this study. We would like to thank the team at the nuclear department of Hebei General Hospital for their assistance.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 > References Top

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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