CT-based 3D dose-volume parameter of the rectum and late rectal complication in patients with cervical cancer treated with high-dose-rate intracavitary brachytherapy

3D-Image-Guided Multi-Catheter Interstitial Brachytherapy for Bulky and High-Risk Stage IIB-IVB Cervical Cancer

Simple Summary

The prognosis of locally advanced cervical cancer still remains poor. Recently, image-guided brachytherapy ameliorated local control and pelvic control in these patients. Additionally, concurrent chemoradiotherapy with interstitial brachytherapy (ISBT) demonstrated more favorable outcomes than that with intracavity brachytherapy. The purpose of our study was to evaluate the efficacy and safety of CT-MRI-guided multi-catheter ISBT for bulky (≥4 cm) and high-risk stage IIB-IVB cervical cancer. Total of 18 patients with squamous cell carcinoma received concurrent chemoradiotherapy with ISBT were assessed. Four (22.2%), seven (38.9%), and seven (38.9%) patients were diagnosed with stage II, III, and IV cervical cancer, respectively. The four-year local control, pelvic control, disease-free survival, and overall survival rates were 100%, 100%, 81.6%, and 87.8%, respectively. Although three (16.7%) patients experienced grade 3 late adverse events, no one had procedure-related complications. CT-MRI-guided multi-catheter ISBT could be a promising treatment strategy for locally advanced cervical cancer.

Abstract

This study aimed to evaluate the efficacy and safety of computed tomography-magnetic resonance imaging (CT-MRI)-guided multi-catheter interstitial brachytherapy for patients with bulky (≥4 cm) and high-risk, stage IIB–IVB advanced cervical cancer. Eighteen patients who underwent concurrent chemoradiotherapy with multi-catheter interstitial brachytherapy between September 2014 and August 2020 were enrolled. The prescribed dose of external beam radiotherapy was 45–50.4 Gy, and the brachytherapy high-dose-rate aim was 25–30 Gy per 5 fractions. The endpoints were four-year local and pelvic control rates, four-year disease-free and overall survival rates, and the adverse events rate. The median follow-up period was 48.4 months (9.1–87.5 months). Fifteen patients received concurrent cisplatin therapy (40 mg/m², q1week). Four (22.2%), seven (38.9%), and seven (38.9%) patients had stage II, III, and IV cervical cancer, respectively. Pelvic and para-aortic lymph node metastases were observed in 11 (61.1%) and 2 (11.1%) patients, respectively. The median pre-treatment volume was 87.5 cm³. The four-year local control, pelvic control, disease-free survival, and overall survival rates were 100%, 100%, 81.6%, and 87.8%, respectively. Three (16.7%) patients experienced grade 3 adverse events, and none experienced grade 4–5 adverse events. CT-MRI-guided multi-catheter interstitial brachytherapy could be a promising treatment strategy for locally advanced cervical cancer.

Role of non-absorbable oral antibiotics in bowel preparation for intracavitary brachytherapy: effects of rifaximin on rectal dosimetric parameters during vaginal cuff brachytherapy

Purpose

Brachytherapy is a major tool for dose escalation in gynecological cancer treatment. Control of rectal repletion is particularly challenging; it can impact dose received by this organ at risk and there are reported toxicities. The use of methods, such as enema and bowel preparation, to reduce rectal volume is a difficult process for patients, and its repeatability requires patients' cooperation. Due to the effect of antibiotics on reducing intestinal gases, this study was conducted to measure the effect of adding rifaximin to bowel preparation on rectal dose-volume histogram (DVH) parameters.

Material and methods

In this prospective interventional study, 24 patients with cervical and endometrial cancer were treated with adjuvant high-dose-rate (HDR) brachytherapy. Both first and second sessions of brachytherapy were performed with bowel preparation, before and after the administration of rifaximin, respectively. The rectum was contoured as an organ at risk, and DVH parameters were recorded and compared in both sessions using magnetic resonance imaging (MRI)-based 3D treatment planning system.

Results

Rifaximin consumption reduced the rectal volume (p = 0.01), but had no significant correlation with other DVH parameters, especially D_2cc (p = 0.599). Moreover, rectal volume had no significant correlation with DVH parameters (all p-values ≤ 0.05).

Conclusions

Even though the addition of rifaximin to bowel preparation significantly reduced rectal volume, no significant difference was observed in DVH parameters. Therefore, it is recommended that adjuvant vaginal cuff HDR brachytherapy should be performed without the use of rifaximin, until further researches' validate its effects.

The Relationship Between Late Morbidity and Dose-Volume Parameter of Rectum in Combined Intracavitary/Interstitial Cervix Cancer Brachytherapy: A Mono-Institutional Experience

Purpose

To establish a dose volume–effect relationship for predicting late rectal complication (LRC) in locally advanced cervical cancer patients treated with external beam radiotherapy (EBRT) followed by combined intracavitary/interstitial brachytherapy (IC/IS-BT).

Materials and Methods

A retrospective analysis was performed in 110 patients with locally advanced cervical cancer who underwent definitive radiotherapy combined with IC/IS-BT from July 2010 to September 2018. We report the 90% of the target volume receiving the minimum dose for high risk clinical target volume (HR-CTV D₉₀) and intermediate risk clinical target volume (IR-CTV D₉₀), and the minimum doses to the most exposed 0.1, 1, and 2 cm³ D0.1cm3,D1cm3,D2cm3 doses at the International Commission on Radiation Units and Measurements (D_ICRU) for organs at risk (OARs). The total dose of EBRT plus brachytherapy was transformed to the biologically equivalent dose in 2 Gy fractions (EQD2) with α/β value of 10 Gy for target, 3 Gy for organs at risk using the linear quadratic model. The morbidity was scored according to the Radiation Therapy Oncology Group (RTOG) criteria. The Probit model was used to establish a prediction model on rectum between the organs at risk for dose and LRC. The receiver operating characteristic (ROC) curve was used to evaluate the predictive value of dose volume parameters for LRC.

Results

The median follow-up time was 72.3 months. The mean ( ± standard deviation) D2cm3,D1cm3,D0.1cm3, and D_ICRU values of rectum were 64.72 ± 7.47 Gy_EQD2, 70.18 ± 5.92 Gy_EQD2, 79.32 ± 7.86 Gy_EQD2, and 67.22 ± 7.87 Gy_EQD2, respectively. The Probit model showed significant relationships between D1cm3 or D0.1cm3, and the probability of grade1–4, grade 2–4 rectal events at 1 year, and between D1cm3and the probability of grade2–4 rectal events at 3 and 5 years. The dose values for 10% complication rates (ED10) of D1cm3were 74.18 (70.42–76.71) Gy_EQD2, 67.80 (59.91, 71.08) Gy_EQD2, 66.37 (52.00, 70.27) Gy_EQD2 for grade 2–4 with rectal morbidity at 1, 3, and 5 years, respectively.

Conclusion

Our study proved that D1cm3 andD0.1cm3were considered as useful dosimetric parameters for predicting the risk of grade1–4 and grade2–4 LRC at 1-year, and D1cm3might be an indicator for predicting grade2-4 LRC at 3/5years. The patients with rectal D1cm3>66.37–74.18 Gy_EQD2 should be closely observed for grade2–4 LRC.

[Dose optimization in 3D pulsed dose rate brachytherapy for patients with locally advanced cervical cancer: A French multicenter phase II trial]

PURPOSE

We present the results of the PHRC Tridicol, a prospective French phase II study whose objective was to increase the dose delivered to the target volume during brachytherapy for locally advanced cervical cancers.

MATERIAL AND METHODS

Eight centers included 48 patients, treated with concomitant radiochemotherapy, then uterovaginal brachytherapy.

RESULTS

The median follow-up was 63 months. The dose of brachytherapy delivered in biological equivalent dose (EQD2) to 90% of the High Risk CTV (D90 CTV HR) was 80Gy in median dose. The 5-year local control rate (LC) was 84%, close to the hypothesis of 86.7%. The rate of severe complications (grade 3-4) was 23% at 5 years. The rectal dose was correlated with the risk of severe complications.

CONCLUSION

HR CTV dose was below the target (85Gy) due to low use of parametrial interstitial needles, as the centers did not always have an adequate applicator, or were at the time at the beginning of their learning curve. The 5-year LC rate was improved compared to that of the comparable STIC PDR group (78%) but lower than the retroEMBRACE cohort of GEC ESTRO (89%). The complication rate was higher than in the comparable group of STIC PDR but close to that of retroEMBRACE. Training brachytherapy teams in interstitial implantation or referring patients to referral centers should help improve the therapeutic index of cervical cancer.

Dosimetric feasibility of computed tomography-based image-guided brachytherapy in locally advanced cervical cancer: a Japanese prospective multi-institutional study

The aim of this study was to assess the feasibility of planning dose-volume histogram (DVH) parameters in computed tomography-based 3D image-guided brachytherapy for locally advanced cervical cancer. In a prospective multi-institutional study, 60 patients with stage IIA2-IVA cervical cancer from eight institutions were treated with external beam radiotherapy using central shielding and intracavitary or hybrid (combined intracavitary/interstitial) brachytherapy (HBT). The dose constraints were set as a cumulative linear quadratic equivalent dose (EQD2) of at least 60 Gy for high-risk clinical target volume (HR-CTV) D90, D2cc ≤ 75 Gy for rectum, D2cc ≤ 90 Gy for bladder and D2cc ≤ 75 Gy for sigmoid. The median HR-CTV D90 was 70.0 Gy (range, 62.8-83.7 Gy) in EQD2. The median D2cc of rectum, bladder and sigmoid was 57.1 Gy (range, 39.8-72.1 Gy), 68.9 Gy (range, 46.5-84.9 Gy) and 57.2 Gy (range, 39.2-71.2 Gy) in EQD2, respectively. In 76 of 233 sessions (33%), 23 patients underwent HBT, and the median number of interstitial needles was 2 (range, 1-5). HBT for a bulky HR-CTV (≥40 cm3) significantly improved the HR-CTV D90 compared with intracavitary brachytherapy alone (P = 0.010). All patients fulfilled the dose constrains for target and at risk organs by undergoing HBT in one-third of sessions. We conclude that the planning DVH parameters used in our protocol are clinically feasible.

Verification of Guiding Needle Placement by Registered Ultrasound Image During Combined Intracavitary/Interstitial Gynecologic Brachytherapy

Purpose

Our previous research demonstrated that under ideal conditions, rigid registration between MRI images and US images had high accuracy for real-time image guidance. The work presented in this paper focused on the application of the previously established procedures to a new context, including preoperative CT images.

Materials and Methods

We used a template to calibrate the US probe and completed the registration between preoperative CT images and US images. Marker experiments on the accuracy of real-time needle trajectories in CT images were performed using micro electromagnetic sensors. Pelvic phantom experiments were carried out to test the registration accuracy between CT and US images, in addition to registration accuracy between US images and real-time needle trajectories (real-time space model).

Results

The US probe calibration error in CT images was 0.879 ± 0.149 mm. The difference of registration between US images and CT images was 0.935 ± 0.166 mm in the axial plane (n = 30) and 0.916 ± 0.143 mm in the sagittal plane (n =12). The difference of registration between US images and the needle’s real-time trajectories was 0.951 ± 0.202 mm.

Conclusion

Under ideal conditions, rigid registration between CT images and US images had high accuracy for real-time image guidance.

Plan-Optimization Method for Central-shielding Pelvic Volumetric-modulated Arc Therapy for Cervical Cancer

AIM

To establish a method of plan optimization in pelvic volumetric-modulated arc therapy (VMAT) for cervical cancer using the central-shielding (CS) principle.

PATIENTS AND METHODS

We created external beam VMAT plans for eight cases with non-bulky stage I-IIb using the CS principle based on the Japanese standard guideline. Clinical target volumes (CTVs) for whole-pelvis (WP) irradiation were created using published guidelines, and CTVs for CS irradiation were created by subtracting the uterus corpus and 4 cm-wide regions centered at the cervix and vagina from the CTVs for WP irradiation. For plan optimization of CS irradiation, a 4-cm diameter cylindrical volume centered in the cervix and vagina was created as the volume receiving a high dose in brachytherapy, and the volume overlapping with the rectum was defined as the Ant-Rectum. Dose-volume histogram (DVH) parameters of two CS VMAT plans with and without (VMAT_OPT/VMAT_NO) dose optimization to the Ant-Rectum were compared.

RESULTS

VMAT_OPT plans resulted in significantly lower DVH parameters of the Ant-Rectum and rectum compared to VMAT_NO plans. These were comparable to the DVH parameters of three-dimensional conformal radiotherapy (3DCRT) plans. Both VMAT plans resulted in significantly better coverage of planning target volumes than did the 3DCRT plans.

CONCLUSION

In the implementation of IMRT/VMAT as the standard treatment for cervical cancer in Japan, our optimization method may be an essential step toward fully benefitting from the CS principle.

A case report of a patient with bulky uterine cervical neoplasm who achieved complete response with "intentional internal high-dose policy" high-dose-rate interstitial brachytherapy

RATIONALE

Gynecological high-dose-rate (HDR) brachytherapy has progressed for years, but it remains difficult for bulky tumors to be controlled locally. Dose limitations to organs at risk (OARs) are invariably obstacles in increasing the prescription dose. Additionally, it is controversial that the excessive hyperdose sleeve, the volume receiving a dose equal to or greater than twice the reference dose, should be eliminated in gynecological HDR brachytherapy. On the other hand, the technique of simultaneous integrated protection was reported for large hepatocellular carcinoma treatment, and similarly, internal high-dose brachytherapy could be used for treating bulky cervical carcinoma.

PATIENT CONCERNS

A 54-year-old female had irregular genital bleeding and lost 13 kg in one year.

DIAGNOSIS

She was diagnosed with T3bN1M0 cervical cancer in another hospital. The transverse diameter of the primary tumor was 10.5 cm.

INTERVENTIONS

The whole pelvis and para-aortic lymph node were irradiated with a total of 50 Gy in 25 fractions, but the size of the tumor showed only a slight decrease to 8.9 cm. After external beam radiotherapy, first-time high-dose-rate interstitial brachytherapy (HDR-ISBT) was administered without "intentional internal high-dose (IIHD) policy," the technique of high-dose administration to only the inside of the tumor. Considering the rectum dose limitation, in the additional 2 times of brachytherapy, "IIHD policy" HDR-ISBT was applied. In the second and third HDR-ISBT, the percentage of the volume exposed to 200% of the prescribed dose for high-risk clinical target volume increased by 241% and 204% compared with the first HDR-ISBT, while the doses to OARs were not significantly higher than those of the first-time HDR-ISBT.

OUTCOMES

Complete response was obtained, and no recurrence findings and side effects caused by HDR-ISBT have been detected for 2 years and 9 months.

LESSONS

To our knowledge, this is the first report of IIHD HDR-ISBT for bulky cervical cancer. This technique can be the solution for treating bulky cervical cancer.

Quantitative analysis of intra-fractional variation in CT-based image guided brachytherapy for cervical cancer patients

We quantified intra-fractional dose variation and organ movement during CT-based 3D-image guided brachytherapy (3D-IGBT) in cervical cancer patients. Fifteen patients who underwent CT-based 3D-IGBT were studied. For all patients, pre-delivery CT for treatment planning after applicator insertion and post-delivery CT after dose delivery without changing the applicator position were acquired. Pre- and post-delivery CT were rigidly fused by matching the inserted applicator and planned dose on pre-delivery CT (pre-delivery dose) was mapped on post-delivery CT (post-delivery dose). D2, D1, and D0.1 cm³ of the rectum and bladder were compared between pre- and post-delivery doses with contours on each CT image. Organ movement and deformation was evaluated using deformation vector fields calculated by deformable image registration between pre- and post-delivery CT. We also evaluated dose variation and DVF between with and without a catheter to control filling. Differences in all DVH parameters were <±3% in physical dose and ± 5% in EQD2. However, a > 15% dose difference was found in 13.8% of the fractions in rectum D2 cm³ and in 11.1% of those in bladder D2 cm³. The mean value of DVF for bladder was larger than that of rectum, especially for the superior-inferior (S-I) direction. Insertion catheters in bladder reduced mean dose and DVF variation compared with that of without catheters. In fraction groups with large dose increasing, DVF in the S-I direction was significantly larger than that of other fraction groups. Our results indicated that preparation is needed to reduce changes in the S-I direction affect dose variation.

Retrospective DVH analysis of point A based intracavitary brachytherapy for uterine cervical cancer

Combining external beam radiotherapy (EBRT) with intracavitary brachytherapy (ICBT) is important for definitive treatment of cervical cancer. In cervical cancer patients receiving radiotherapy, we evaluated treatment outcomes in relation to dose-volume histogram parameters, including the computed tomography (CT)-based high-risk clinical target volume (HR-CTV) for ICBT. Between 2010 and 2015, 89 consecutive cervical cancer patients were mostly treated with 40 Gy of EBRT in 20 fractions and 18 Gy of ICBT prescribed to point A in 3 fractions. CT scans were obtained during ICBT. The HR-CTV D90 was calculated and the total doses of ICBT and EBRT were converted to the equivalent dose in 2 Gy fractions (EQD2). When the patients were divided into four groups according to EQD2 of the HR-CTV D90, the 3-year local recurrence-free survival rates were 95.2, 78.4, 52.7 and 42.9% for patients receiving >80 , 70-80 , 60-70 and <60 Gy, respectively. There was a significant negative correlation between EQD2 of the HR-CTV D90 and the HR-CTV volume at first ICBT (r = -0.713). Local recurrence was more frequent when the HR-CTV volume was ≥22 cc and EQD2 of the HR-CTV D90 was <70 Gy. Multivariate analysis showed that EQD2 of the HR-CTV D90 and concurrent chemotherapy (≥4 cycles) were significant determinants of overall survival. HR-CTV D90 was an important prognostic indicator for local recurrence. HR-CTV D90 >70 Gy is required for the better local control, especially in patients with a larger HR-CTV (≥22 cc at initial ICBT).

Definitive radiotherapy consisting of whole pelvic radiotherapy with no central shielding and CT-based intracavitary brachytherapy for cervical cancer: feasibility, toxicity, and oncologic outcomes in Japanese patients

BACKGROUND

This prospective study investigated the feasibility, toxicity, and oncologic outcomes of definitive radiotherapy (RT) consisting of whole pelvic radiotherapy with no central shielding (noCS-WPRT) and CT-based intracavitary brachytherapy (ICBT) in Japanese patients with cervical cancer.

METHODS

Patients with cervical cancer of FIGO stages IB1-IVA were eligible. The treatment protocol consisted of noCS-WPRT of 45 Gy in 25 fractions and CT-based high dose-rate ICBT of 15 or 20 Gy in 3 or 4 fractions prescribed at point A. The prescribed ICBT dose was decreased if the manual dwell time/position optimization failed to meet organs-at-risk constraints. Graphical optimization and additional interstitial needles were not applied.

RESULTS

We enrolled 40 patients. FIGO stages were IB1: 11, IB2: 13, IIA2: 1, IIB: 11, IIIB: 3, and IVA: 1. Median (range) pretreatment tumor diameter was 47 (14-81) mm. Point A doses were decreased in 19 of 153 ICBT sessions (12%). The median follow-up duration was 33 months. The 2-year rates of pelvic control, local control (LC), and progression-free survival were 83%, 85%, and 75%, respectively. Pre-ICBT tumor diameter, high-risk clinical target volume (HR-CTV), total HR-CTV D90, and overall treatment time (OTT) significantly affected LC. Late adverse events (grade ≥ 3) were observed in 3 patients (2 in the bladder, 1 in the rectum).

CONCLUSIONS

Definitive RT consisting of noCS-WPRT and CT-based ICBT was feasible for Japanese patients with cervical cancer. To further improve LC, additional interstitial needles for patients with a large HR-CTV and shorter OTT should be considered.

Impact of CT-based brachytherapy in elderly patients with cervical cancer

PURPOSE

Three-dimensional image-guided brachytherapy (3D-IGBT) has become the standard therapy for patients with cervical cancer. However, in this population, the impact of 3D-IGBT in elderly individuals remains unknown. This study assessed the efficacy of 3D-IGBT for elderly patients with cervical cancer.

METHODS AND MATERIALS

We performed a retrospective chart review of 105 consecutive patients with cervical squamous cell carcinoma aged ≥70 years who received radiotherapy alone between January 2001 and September 2014. All patients were treated with external beam radiotherapy and high-dose-rate intracavitary brachytherapy. We assessed the treatment outcomes in all patients. We then compared outcomes between two groups: patients treated by changing the Point A dose at brachytherapy (Group A, n = 71) and those treated with 3D-IGBT at least twice (Group B, n = 34).

RESULTS

The median followup period was 59 (range, 6-203) months; the median age was 77 years. The 5-year local control and cause-specific survival rates were 89% and 78%, respectively. The 5-year cumulative rates of late toxicities of the rectum and bladder of Grade ≥3 were 2.0% and 4.2%, respectively. No statistically significant differences were observed in the local control and cause-specific survival rates, or in the incidence of rectal toxicities between groups. The 3-year cumulative rates of urinary toxicity of Grade ≥1 were 20.4% and 6.9% in Group A and Group B, respectively (p = 0.035).

CONCLUSION

In elderly patients with cervical cancer, 3D-IGBT could be performed safely and effectively and contributed to decreasing urinary toxicity incidence rates.

Comparison of clinical outcome between computed tomography-based image-guided brachytherapy and two-dimensional-based brachytherapy for cervical cancer

This study aimed to analyze the clinical results of radiotherapy for cervical cancer using two-dimensional (2D) intracavitary brachytherapy (ICBT) and computed tomography (CT)-based image-guided brachytherapy (IGBT) at our institution. Patients with stage IB–IVA cervical cancer who received ICBT between April 2008 and April 2014 were included in this study. In total 58 patients were assessed. The first 38 patients received ICBT with the 2D treatment plan (the 2D group), and the remaining 20 patients received CT-based IGBT (the IGBT group). The dose of point A tended to be lower in the IGBT group (mean value, 60.6 Gy vs. 62.5 Gy; p = .07), though the minimum dose to the 90% (D90) of the clinical target volume (CTV) was equivalent in both groups (mean value, 66.0 Gy vs. 66.2 Gy; p = .91). The rectum minimum dose to 2 cc (D2cc) was significantly lower in the IGBT group than in the 2D group (mean value, 61.2 Gy vs. 69.1 Gy; p = .001). With a median follow-up time of 60 months, the 5-year local control rates (LCRs) of the IGBT group and 2D group were 100% and 83%, respectively (p = .12). The 5-year incidence of rectal complications in the IGBT group and the 2D group were 11% and 29%, respectively (p = .26). Our study showed favorable LCR and preferred incidence of rectal complications in patients treated with CT-based IGBT.

•

The difference of the treatment results between 2D and 3D brachytherapy was analyzed.

•

The rectum D2cc was significantly lower in the IGBT group compared with the 2D group.

•

Local control rates tended to be better in the IGBT group than in the 2D group.

•

The incidence of rectal complications tended to be lower in the IGBT group.

Hyaluronate gel injection for rectum dose reduction in gynecologic high-dose-rate brachytherapy: initial Japanese experience

Perirectal hyaluronate gel injection (HGI) appears to be a promising technique for healthy tissue dose sparing in pelvic radiotherapy. In this analysis, we report our initial experience of HGI in gynecologic brachytherapy, focusing on its safety and effectiveness for dose reduction to the rectum. Between July 2013 and May 2014, 36 patients received HGI for primary/salvage gynecologic brachytherapy. Dosimetric effect analysis was based on pre- and post-HGI computed tomography dataset registration with corresponding dose-volume histogram evaluation. The maximum dose to the most exposed 0.1 cm3 (D0.1cm3) and 2.0 cm3 (D2.0cm3) were used as index values for rectum and bladder dose evaluation. The dose indexes for target volume (TV) coverage were TV D90/V100. In all cases, HGI was well tolerated, with no acute or late adverse events documented at a median follow-up of 220 days (range, 18-1046 days). Rectum D2.0cm3 and D0.1cm3 were significantly decreased by HGI (P < 0.001 and P = 0.003, respectively), with no significant impact on dosimetric parameters of bladder and TV coverage. Factors correlating negatively with the dosimetric effect of HGI were an increasing number of interstitial catheters (P = 0.003) as well as Lcranial100% (P = 0.014) and Lcranial80% (P = 0.001) [i.e. the length from the anal verge to the most cranial point at which the 100% and 80% isodose lines, respectively, crossed the rectum]. The concept of HGI for gynecologic brachytherapy is plausible, and our initial experience indicates it to be an effective technique for rectal dose reduction in radiotherapy of intrapelvic tumours.

Analysis of late adverse events and their chronological changes after radiation therapy for cervical cancer

Several late adverse events occur after radiation therapy (RT) for cervical cancer. However, there has been little reported about their chronological changes. It is still unclear whether concurrent chemoradiotherapy (CCRT) increases late complications. We aimed to evaluate the late adverse events and their chronological changes and whether CCRT increases their incidence and severity. For this purpose, we retrospectively analyzed 157 women with histologically proven cervical cancer. We reviewed all late adverse events and compared the frequency and severity between the patients who underwent CCRT and those who underwent RT alone. We calculated the cumulative occurrence rates of late adverse events stratified by the site and severity, and determined the chronological changes. With survivors' median follow-up time of 74.3 months, late adverse events occurred in 49.0% and serious complications developed in 24.2% of all patients. There was no significant difference in the cumulative incidence rate of all late adverse events between the CCRT and RT-alone groups (p = 0.720). The incidence rate of rectal bleeding was 25.5%. Serious rectal bleeding developed in 5 patients, all within 20 months from the start of RT. Importantly, the symptoms of rectal bleeding disappeared or were relieved in most patients during follow-up. In conclusion, we evaluated the late adverse events and their chronological changes after RT for cervical cancer and showed that adding chemotherapy to RT did not affect the frequency and severity of late complications, and the symptoms of rectal bleeding were relieved over time.

Dosimetric research into target regions and organs at risk in three-dimensional intracavitary brachytherapy techniques for Chinese patients with cervical carcinoma

The present study aimed to compare the dosages of target regions and organs at risk (OARs) in 3D intracavitary brachytherapy (ICBT) and conventional 2D ICBT for Chinese patients with cervical carcinoma. ICBT was performed in a total of 66 patients with Stage IB to IVA cervical carcinoma who had not received surgery but who had received whole-pelvic external-beam radiotherapy (EBRT). Plans for the 3D-ICBT and the conventional 2D-ICBT were individually designed for every patient. The dosages differences between the target regions and the OARs in patients with each of the various stages of cervical carcinoma were compared between the two ICBT plans. There was no significant difference in the dose at Point A between the two ICBT plans. However, the CTVhr-D90, CTVhr-D100 and CTVir-D90 in 3D-ICBT were much higher than in 2D-ICBT, especially in Stage IIB (P < 0.05). As compared with conventional 2D-ICBT, the dosages of DICRU and D2.0cm3 in the rectum/bladder, and D2.0cm3 in the sigmoid/small bowel were decreased significantly in 3D-ICBT (P < 0.05). For patients with Stage IIA, IIB and IIIB, the D2.0cm3 in the rectum/bladder was significantly reduced in 3D-ICBT (P < 0.05). It was demonstrated that, in Chinese patients, 3D-ICBT for cervical carcinoma could optimize the target coverage and reduce the dosages to the OARs compared with conventional 2D-ICBT.

Computed tomography-based image-guided brachytherapy for cervical cancer: correlations between dose-volume parameters and clinical outcomes

This study evaluated the oncologic outcomes and complications of cervical cancer patients in terms of CT-based image-guided brachytherapy (IGBT) parameters. Of 68 cervical cancer patients treated with definitive radiotherapy/concurrent chemoradiotherapy, most received whole-pelvis external beam RT (EBRT) of 40 Gy in 20 fractions, pelvic EBRT with central shield of 10 Gy in 5 fractions, and CT-based IGBT of 18 Gy in 3 fractions prescribed to point A. Cumulative EBRT and IGBT doses were calculated as the total equivalent dose in 2 Gy fractions (EQD2). The median follow-up was 31 (3-52) months. The 2-year overall survival, local control, pelvic control, and disease-free survival rates of the 68 patients were 92%, 83%, 82% and 73%, respectively. The HR-CTV D90, length from the tandem axis to left/right margin of the HR-CTV (T-LR), and HR-CTV volume were significant IGBT parameters for predicting local/pelvic control. Patients who received an HR-CTV D90 of >60 Gy, compared with ≤60 Gy, had significantly better local/pelvic control. Furthermore, 70 Gy was a marginally significant HR-CTV D90 cut-off affecting local control. T-LR was an independent IGBT parameter predicting local/pelvic control on multivariate analysis. Three patients developed Grade 3 or higher treatment-related complications. The D2cm3 of organs at risk were not significant predictors of complications. Future challenges for further improving outcomes include additional interstitial needles for irregularly shaped HR-CTVs, and moderate dose escalation, especially for patients with poor tumor responses.

Evaluation of rectum and bladder dose accumulation from external beam radiotherapy and brachytherapy for cervical cancer using two different deformable image registration techniques

We evaluated dose-volume histogram (DVH) parameters based on deformable image registration (DIR) between brachytherapy (BT) and external beam radiotherapy (EBRT) that included a center-shielded (CS) plan. Eleven cervical cancer patients were treated with BT, and their pelvic and CS EBRT were studied. Planning CT images for EBRT and BT (except for the first BT, used as the reference image) were deformed with DIR to reference image. We used two DIR parameter settings: intensity-based and hybrid. Mean Dice similarity coefficients (DSCs) comparing EBRT with the reference for the uterus, rectum and bladder were 0.81, 0.77 and 0.83, respectively, for hybrid DIR and 0.47, 0.37 and 0.42, respectively, for intensity-based DIR (P < 0.05). D1 cm3 for hybrid DIR, intensity-based DIR and DVH addition were 75.1, 81.2 and 78.2 Gy, respectively, for the rectum, whereas they were 93.5, 92.3 and 94.3 Gy, respectively, for the bladder. D2 cm3 for hybrid DIR, intensity-based DIR and DVH addition were 70.1, 74.0 and 71.4 Gy, respectively, for the rectum, whereas they were 85.4, 82.8 and 85.4 Gy, respectively, for the bladder. Overall, hybrid DIR obtained higher DSCs than intensity-based DIR, and there were moderate differences in DVH parameters between the two DIR methods, although the results varied among patients. DIR is only experimental, and extra care should be taken when comparing DIR-based dose values with dose-effect curves established using DVH addition. Also, a true evaluation of DIR-based dose accumulation would require ground truth data (e.g. measurement with physical phantom).

American Brachytherapy Task Group Report: A pooled analysis of clinical outcomes for high-dose-rate brachytherapy for cervical cancer

PURPOSE

Advanced imaging used in combination with brachytherapy (BT) has revolutionized the treatment of patients with cervical cancer. We present a comprehensive review of the literature for definitive radiation with high-dose-rate (HDR) BT. In addition, we investigate potential outcome improvement with image-based brachytherapy (IBBT) compared to studies using traditional Point A dosing. This review extensively investigates acute and late toxicities.

METHODS AND MATERIALS

This study reviews the literature from 2000 to 2015 with an emphasis on modern approaches including concurrent chemotherapy (chemoRT), radiation, and HDR BT and IBBT. Descriptive statistics and pelvic control (PC), disease-free survival (DFS), and overall survival (OS) outcomes were calculated using weighted means to report pooled analysis of outcomes.

RESULTS

Literature search yielded 16 prospective, 51 retrospective studies that reported survival outcomes, and 13 retrospective studies that focused on acute and late toxicity outcomes regardless of applicator type. There are 57 studies that report Point A dose specification with 33 having chemoRT, and 10 studies that use IBBT, 8 with chemoRT. Patients receiving radiation and chemoRT with HDR BT in the prospective studies, with >24 months followup, rates of PC were: for RT: 73%, SD: 11; CRT: 82%, SD: 8; DFS-RT: 55%, SD: 10; CRT: 65%, SD: 7; OS-RT: 66%, SD: 7; CRT: 70%, SD: 11. In the retrospective studies, the PC rates (weighted means) for the radiation and chemoradiation outcomes are 75% vs. 80%, and for DFS, the values were 55% vs. 63%, respectively. Comparing patients receiving chemoRT and IBBT to traditional Point A dose specification, there is a significant improvement in PC (p < 0.01) and DFS (p < 0.01) with IBBT. The range of genitourinary late toxicity reported for radiation was Grade 3: 1-6% and for chemoRT 2-20%. The range of late gastrointestinal toxicity for radiation was Grade 3: 4-11% and for chemoRT, 1-11%. For the late gynecologic toxicity, only 1 of the 16 prospective trials report a Grade 1-2 of 17% for radiation and 9% for chemoRT effects.

CONCLUSIONS

We present concise outcomes of PC, DFS, OS, and toxicity for cervical cancer patients treated with chemoradiation and HDR BT. Our data suggest an improvement in outcomes with the use of IBBT compared with traditional Point A dose prescriptions. In conclusion, HDR BT is a safe, effective modality when combined with IBBT.

In-room computed tomography-based brachytherapy for uterine cervical cancer: results of a 5-year retrospective study

Herein, we investigate the long-term clinical outcomes for cervical cancer patients treated with in-room computed tomography-based brachytherapy. Eighty patients with Stage IB1-IVA cervical cancer, who had undergone treatment with combined 3D high-dose rate brachytherapy and conformal radiotherapy between October 2008 and May 2011, were retrospectively analyzed. External beam radiotherapy (50 Gy) with central shielding after 20-40 Gy was performed for each patient. Cisplatin-based chemotherapy was administered concurrently to advanced-stage patients aged ≤75 years. Brachytherapy was delivered in four fractions of 6 Gy per week. In-room computed tomography imaging with applicator insertion was performed for treatment planning. Information from physical examinations at diagnosis, and brachytherapy and magnetic resonance imaging at diagnosis and just before the first brachytherapy session, were referred to for contouring of the high-risk clinical target volume. The median follow-up duration was 60 months. The 5-year local control, pelvic progression-free survival and overall survival rates were 94%, 90% and 86%, respectively. No significant differences in 5-year local control rates were observed between Stage I, Stage II and Stage III-IVA patients. Conversely, a significant difference in the 5-year overall survival rate was observed between Stage II and III-IVA patients (97% vs 72%; P = 0.006). One patient developed Grade 3 late bladder toxicity. No other Grade 3 or higher late toxicities were reported in the rectum or bladder. In conclusion, excellent local control rates were achieved with minimal late toxicities in the rectum or bladder, irrespective of clinical stage.

The use of trans-applicator intracavitary ultrasonography in brachytherapy for cervical cancer: phantom study of a novel approach to 3D image-guided brachytherapy

Purpose

To assess the feasibility of applying trans-applicator intracavitary ultrasonography to image-guided brachytherapy for cervical cancer.

Material and methods

For this experiment, a phantom was created and included a polyethylene tube, intended to simulate a tandem applicator, which was inserted into chicken meat and embedded in agar, along with magnetic resonance imaging (MRI)-compatible ovoid applicators. Three-dimensional images of the phantom were obtained using computed tomography (CT), MRI (T2-weighted), and intracavitary ultrasonography sectional images acquired at 1 mm slice intervals. Intracavitary ultrasonography images were acquired from within the simulated tandem applicator using a radial transducer. Magnetic resonance imaging and intracavitary ultrasonography images were manually registered onto CT images. The chicken meat was contoured as the target volume independently on the CT, MRI, and intracavitary ultrasonography images, and the Dice similarity coefficient was used to compare the target volumes. The dose distributions of a sample brachytherapy plan were also evaluated.

Results

Computed tomography, MRI, and intracavitary ultrasonography all visualized the three-dimensional phantom volumes. Intracavitary ultrasonography images depicted the meat with high echoic signals and a border clearly distinguishable from the surrounding agar. The Dice similarity coefficient values for the target volumes on CT vs. MRI, CT vs. intracavitary ultrasonography, and MRI vs. intracavitary ultrasonography were 0.966, 0.965, and 0.971, respectively, indicating similar contouring with the three modalities. Among the modalities, the differences in D₅₀, D₉₀, D₉₈, and D₁₀₀ values were 1.8%, 2.9%, 3.7%, and 2.9%, respectively.

Conclusions

Three-dimensional reconstructed trans-applicator intracavitary ultrasonographic images clearly depicted meat tissue within the phantom, and could thus be used for brachytherapy planning. This study proves the concept of trans-applicator intracavitary ultrasonography for intracavitary brachytherapy. Further research such as development of intracavitary ultrasonography system, 3D reconstruction method, ultrasonography-compatible applicators, and ultrasonography-based target concept is warranted to assess the potential clinical application.

Recommendations for high-risk clinical target volume definition with computed tomography for three-dimensional image-guided brachytherapy in cervical cancer patients

Our purpose was to develop recommendations for contouring the computed tomography (CT)-based high-risk clinical target volume (CTVHR) for 3D image-guided brachytherapy (3D-IGBT) for cervical cancer. A 15-member Japanese Radiation Oncology Study Group (JROSG) committee with expertise in gynecological radiation oncology initiated guideline development for CT-based CTVHR (based on a comprehensive literature review as well as clinical experience) in July 2014. Extensive discussions occurred during four face-to-face meetings and frequent email communication until a consensus was reached. The CT-based CTVHR boundaries were defined by each anatomical plane (cranial-caudal, lateral, or anterior-posterior) with or without tumor progression beyond the uterine cervix at diagnosis. Since the availability of magnetic resonance imaging (MRI) with applicator insertion for 3D planning is currently limited, T2-weighted MRI obtained at diagnosis and just before brachytherapy without applicator insertion was used as a reference for accurately estimating the tumor size and topography. Furthermore, utilizing information from clinical examinations performed both at diagnosis and brachytherapy is strongly recommended. In conclusion, these recommendations will serve as a brachytherapy protocol to be used at institutions with limited availability of MRI for 3D treatment planning.

Dosimetric and radiobiological comparison of Cyberknife and Tomotherapy in stereotactic body radiotherapy for localized prostate cancer

BACKGROUND AND PURPOSE

As recent studies have suggested relatively low α/β for prostate cancer, the interest in hypofractionated stereotactic body radiotherapy (SBRT) for prostate cancer is rising. The aim of this study is to compare dosimetric results of Cyberknife (CK) with Tomotherapy (HT) in SBRT for localized prostate cancer. Furthermore, the radiobiologic consequences of heterogeneous dose distribution are also analyzed.

MATERIAL AND METHOD

A total of 12 cases of localized prostate cancer previously treated with SBRT were collected. Treatments had been planned and delivered using CK. Then HT plans were generated for comparison afterwards. The prescribed dose was 37.5Gy in 5 fractions. Dosimetric indices for target volumes and organs at risk (OAR) were compared. For radiobiological evaluation, generalized equivalent uniform dose (gEUD) and normal tissue complication probability (NTCP) were calculated and compared.

RESULT

Both CK and HT achieved target coverage while meeting OAR constraints adequately. HT plans resulted in better dose homogeneity (Homogeneity index: 1.04±0.01 vs. 1.21±0.01; p = 0.0022), target coverage (97.74±0.86% vs. 96.56±1.17%; p = 0.0076) and conformity (new vonformity index: 1.16±0.05 vs. 1.21±0.04; p = 0.0096). HT was shown to predict lower late rectal toxicity as compared to CK. Integral dose to body was also significantly lower in HT plans (46.59±6.44 Gy'L vs 57.05±11.68 Gy'L; p = 0.0029).

CONCLUSION

Based on physical dosimetry and radiobiologic considerations, HT may have advantages over CK, specifically in rectal sparing which could translate into clinical benefit of decreased late toxicities.

Outcomes with volume-based dose specification in CT-planned high-dose-rate brachytherapy for stage I-II cervical carcinoma: A 10-year institutional experience

OBJECTIVE

To determine prognostic factors for progression-free survival (PFS) and overall survival (OS) for stage I-II cervical-cancer patients treated using computed-tomography (CT)-planned high-dose-rate (HDR) intracavitary brachytherapy (BT).

METHODS

A total of 150 patients were treated for Stage I-II cervical cancer using CT-planned BT between 4/2004 and 10/2014. Of these, 128 were eligible for inclusion. Kaplan-Meier local control (LC), pelvic control (PC), overall survival (OS), and PFS estimates were calculated.

RESULTS

After a median follow-up of 30months, the 2-year LC rate was 96%, PFS was 88%, and OS was 88%. Overall, 18 patients (14%) experienced any recurrence (AR), 8 had distant recurrence only and 10 had a combination of local, pelvic, regional, and distant recurrence. No patients had LR only. A prognostic factor for AR was tumor size >4cm (p=0.01). Patients with tumors >4cm were 3.3 times more likely to have AR than those with tumors ≤4cm (hazard ratio [HR]=3.3; 95% confidence interval [CI] 1.28-9.47). Point A was 85% of prescription for tumors < 4 cm and decreased approximately 3% over 5 fractions compared to 90% of prescription for tumors > 4 cm that decreased approximately 4% over 5 fractions. Two patients (2%) experienced grade≥2 late toxicity. There were no acute or late grade≥3 toxicities.

CONCLUSION

CT-planned BT resulted in excellent local control and survival. Large tumor size was associated with an increased risk of recurrence outside the radiation field and worse PFS and OS. A volume-optimized plan treated a smaller area than a point A standard plan for patients with Stage I-II cervical cancer that have received chemoradiation. Given the outstanding LC achieved with modern therapy including chemoradiation, HDR, and image-based BT, further efforts to combat spread outside the radiation field with novel therapies are warranted.

Late rectal toxicity determined by dose-volume parameters in computed tomography-based brachytherapy for locally advanced cervical cancer

The aim of this study was to observe the relationship between dose–volume histogram (DVH) parameters and rectal late side effects (LSE) in computed tomography (CT)‐based brachytherapy (BT) for patients with locally advanced cervical cancer. In total, 144 cervical cancer patients received external beam radiotherapy and CT‐based BT. The data from 111 survival cases with pelvic local control (LC) were used to analyze the relationship between DVH parameters and rectal LSE. The total doses, manifesting 2, 1, and 0.1 cm³ (D_2cc, D_1cc, and D_0.1cc) of the rectum, and D₉₀ for high‐risk clinical target volume (HR CTV) were computed and normalized to 2 Gy fractions (EQD2) using a linear‐quadratic model. The rectal LSE were evaluated by the late effects in normal tissues‐subjective, objective, management, and analytic (LENT‐SOMA) scale. A dose–response relationship was evaluated by probit analyses. For all patients, the total rate of rectal LSE was 56%, and the rate of ≥Grade 2 LSE was 27.4%. For the 111 survival cases with pelvic LC, the total mean for D_2cc was 71.23 ± 5.54 Gy for the rectum, and the D_2cc, D_1cc, and D_0.1cc values for Grades 2 and 3 were higher than those for Grades 0 and 1. In addition, the number of complications increased, and the complications became more severe as the dose increased, with a dose of 73.5 Gy resulting in a 10% probability of ≥Grade 3 LSE. In conclusion, DVH parameters could predict the incidence and grades of rectal LSE in CT‐based BT. D_2cc showed an excellent predictive value, and 73.5 Gy for D_2cc of the rectum might be considered as an alternative dose limit.

Simulation analysis of optimized brachytherapy for uterine cervical cancer: Can we select the best brachytherapy modality depending on tumor size?

PURPOSE

To choose the optimal brachytherapeutic modality for uterine cervical cancer, we performed simulation analysis.

METHODS AND MATERIALS

For each high-risk clinical target volume (HR CTV), we compared four modalities [classical conventional intracavitary brachytherapy (ConvICBT), Image-guided ICBT (IGICBT), intracavitary/interstitial brachytherapy (ICISBT), and interstitial brachytherapy (ISBT) with perineal approach] using dose-volume histograms using eight sizes of HR CTV (2 × 2 × 2 cm to 7 × 4 × 4 cm) and organs at risk model.

RESULTS

In ConvICBT, the doses covered 90% of the HR CTV [D90(HR CTV)] decreased from 197% prescribed dose (PD) for the HR CTV size (2 × 2 × 2 cm) to 73% PD for 5 × 4 × 4 cm, whereas the other three modalities could achieve 100% PD for all HR CTV sizes. The minimum doses received by the maximally irradiated 2-cm(3) volumes for organs at risks of IGICBT demonstrated lower values than those of ConvICBT for the HR CTV size of 4 × 3 × 3 cm or smaller. ICISBT demonstrated lower values than those of IGICBT for 4 × 3 × 3 cm or larger. ISBT demonstrated lowest values for 5 × 4 × 4 cm or larger.

CONCLUSIONS

HR CTV size of 4 × 3 × 3 cm seems to be a threshold volume in this simulation analysis, and IGICBT is a better choice for smaller HR CTV than the threshold volume. On larger HR CTV, ICISBT or ISBT is the better choice.

Assessing cumulative dose distributions in combined radiotherapy for cervical cancer using deformable image registration with pre-imaging preparations

Background

The purpose of the study was to evaluate the feasibility of deformable image registration (DIR) in assessing cumulative dose distributions of the combination of external beam radiotherapy (EBRT) and fractionated intracavitary brachytherapy (ICBT) for cervical cancer.

Materials and methods

Three-dimensional image data sets of five consecutive patients were used. The treatment plan consisted of whole pelvic EBRT (total dose: 45 Gy in 25 fractions) combined with computed tomography (CT)-based high-dose rate ICBT (≥24 Gy in 4 fractions to the high risk clinical target volume (HR-CTV)). Organs at risk and HR-CTV were contoured on each CT images and dose-volume parameters were acquired. Pre-imaging preparations were performed prior to each ICBT to minimize the uncertainty of the organ position. Physical doses of each treatment were converted to biologically equivalent doses in 2 Gy daily fractions by the linear quadratic model. Three-dimensional dose distributions of each treatment were accumulated on CT images of the first ICBT using DIR with commercially available image registration software (MIM Maestro®). To compare with DIR, 3D dose distributions were fused by rigid registration based on bony structure matching. To evaluate the accuracy of DIR, the Dice similarity coefficient (DSC) was measured between deformed contours and initial contours.

Results

The cumulative dose distributions were successfully illustrated on the CT images using DIR. Mean DSCs of the HR-CTV, rectum, and bladder were 0.46, 0.62 and 0.69, respectively, with rigid registration; and 0.78, 0.76, and 0.87, respectively, with DIR (p <0.05). The mean DSCs derived from our DIR procedure were comparable to those of previous reports describing the quality of DIR algorithms in the pelvic region. DVH parameters derived from the 2 methods showed no significant difference.

Conclusions

Our results suggest that DIR-based dose accumulation may be acceptable for assessing cumulative dose distributions to assess doses to the tumor and organs at risk in combined radiotherapy for cervical cancer under pre-imaging preparations.

Can combined intracavitary/interstitial approach be an alternative to interstitial brachytherapy with the Martinez Universal Perineal Interstitial Template (MUPIT) in computed tomography-guided adaptive brachytherapy for bulky and/or irregularly shaped gynecological tumors?

Background

Interstitial brachytherapy (ISBT) is an optional treatment for locally advanced gynecological tumours for which conventional intracavitary brachytherapy (ICBT) would result in suboptimal dose coverage. However, ISBT with Martinez Universal Perineal Interstitial Template (MUPIT), in which ~10-20 needles are usually applied, is more time-consuming and labor-intensive than ICBT alone, making it a burden on both practitioners and patients. Therefore, here we investigated the applicability of a combined intracavitary/interstitial (IC/IS) approach in image-guided adaptive brachytherapy for bulky and/or irregularly shaped gynecological tumours for which interstitial brachytherapy (ISBT) was performed.

Methods

Twenty-one consecutive patients with gynecological malignancies treated with computed tomography-guided ISBT using MUPIT were analyzed as cases for this dosimetric study. For each patient, the IC/IS plan using a tandem and 1 or 2 interstitial needles, which was modeled after the combined IC/IS approach, was generated and compared with the IS plan based on the clinical ISBT plan, while the IC plan using only the tandem was applied as a simplified control. Maximal dose was prescribed to the high-risk clinical target volume (HR-CTV) while keeping the dose constraints of D_2cc bladder < 7.0 Gy and D_2cc rectum < 6.0 Gy. The plan with D90 HR-CTV exceeding 6.0 Gy was considered acceptable.

Results

The average D90 HR-CTV was 77%, 118% and 140% in the IC, IC/IS and IS plans, respectively, where 6 Gy corresponds to 100%. The average of the ratio of D90 HR-CTV to D_2cc rectum (gain factor (GF) _rectum) in the IC, IC/IS and IS plans was 0.8, 1.3 and 1.5 respectively, while GF_bladder was 0.9, 1.4 and 1.6, respectively. In the IC/IS plan, D90 HR-CTV, GF_rectum and GF_bladder exceeded 100%, 1.0 and 1.0, respectively, in all patients.

Conclusions

These data demonstrated that the combined IC/IS approach could be a viable alternative to ISBT for gynecological malignancies with bulky and/or irregularly shaped tumours.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-014-0222-6) contains supplementary material, which is available to authorized users.

Dose-volume histogram parameters of high-dose-rate brachytherapy for Stage I-II cervical cancer (≤4cm) arising from a small-sized uterus treated with a point A dose-reduced plan

We investigated the rectal dose-sparing effect and tumor control of a point A dose-reduced plan in patients with Stage I-II cervical cancer (≤4 cm) arising from a small-sized uterus. Between October 2008 and August 2011, 19 patients with Stage I-II cervical cancer (≤4 cm) were treated with external beam radiotherapy (EBRT) for the pelvis and CT-guided brachytherapy. Seven patients were treated with brachytherapy with standard loading of source-dwell positions and a fraction dose of 6 Gy at point A (conventional brachy-plan). The other 12 patients with a small uterus close to the rectum or small intestine were treated with brachytherapy with a point A dose-reduction to match D2cc of the rectum and <6 Gy as the dose constraint ('point A dose-reduced plan') instead of the 6-Gy plan at point A ('tentative 6-Gy plan'). The total doses from EBRT and brachytherapy were added up and normalized to a biological equivalent dose of 2 Gy per fraction (EQD2). The median doses to the high-risk clinical target volume (HR-CTV) D90 in the conventional brachy-plan, tentative 6-Gy plan and point A dose-reduced plan were 62 GyEQD2, 80 GyEQD2 and 64 GyEQD2, respectively. The median doses of rectal D2cc in the corresponding three plans were 42 GyEQD2, 62 GyEQD2 and 51 GyEQD2, respectively. With a median follow-up period of 35 months, three patients developed Grade-1 late rectal complications and no patients developed local recurrence. Our preliminary results suggested that CT-guided brachytherapy using an individualized point A dose-reduced plan might be useful for reducing late rectal complications while maintaining primary tumor control.

The association of rectal equivalent dose in 2 Gy fractions (EQD2) to late rectal toxicity in locally advanced cervical cancer patients who were evaluated by rectosigmoidoscopy in Faculty of Medicine, Chiang Mai University

Purpose

To evaluate association between equivalent dose in 2 Gy (EQD2) to rectal point dose and gastrointestinal toxicity from whole pelvic radiotherapy (WPRT) and intracavitary brachytherapy (ICBT) in cervical cancer patients who were evaluated by rectosigmoidoscopy in Faculty of Medicine, Chiang Mai University.

Materials and Methods

Retrospective study was designed for the patients with locally advanced cervical cancer, treated by radical radiotherapy from 2004 to 2009 and were evaluated by rectosigmoidoscopy. The cumulative doses of WPRT and ICBT to the maximally rectal point were calculated to the EQD2 and evaluated the association of toxicities.

Results

Thirty-nine patients were evaluated for late rectal toxicity. The mean cumulative dose in term of EQD2 to rectum was 64.2 Gy. Grade 1 toxicities were the most common findings. According to endoscopic exam, the most common toxicities were congested mucosa (36 patients) and telangiectasia (32 patients). In evaluation between rectal dose in EQD2 and toxicities, no association of cumulative rectal dose to rectal toxicity, except the association of cumulative rectal dose in EQD2 >65 Gy to late effects of normal tissue (LENT-SOMA) scale ≥ grade 2 (p = 0.022; odds ratio, 5.312; 95% confidence interval, 1.269-22.244).

Conclusion

The cumulative rectal dose in EQD2 >65 Gy have association with ≥ grade 2 LENT-SOMA scale.

Interfractional change of high-risk CTV D90 during image-guided brachytherapy for uterine cervical cancer

The purpose of this study was to evaluate interfractional changes of the minimum dose delivered to 90% of the high-risk clinical target volume (HR-CTV D90) and D2cc of the bladder and rectum during brachytherapy for uterine cervical cancer patients. A total of 52 patients received external beam radiotherapy and high-dose-rate intracavitary brachytherapy (ICBT). For each of four ICBT applications, a pelvic CT scan was performed and the HR-CTV was delineated. Retrospectively, these patients were divided into two groups: (i) the standard dose group with 6 Gy to point A in each ICBT, and (ii) the adaptive dose group with a modified dose to point A to cover the HR-CTV with the 6-Gy isodose line as much as possible. The HR-CTV D90 was assessed in every session, and analyzed as interfractional changes. In the standard dose group, the interfractional changes of the HR-CTV D90 showed a linear increase from the first to the third of the four ICBT (average 6.1, 6.6, 7.0 and 7.1 Gy, respectively). In contrast, those of the adaptive dose group remained almost constant (average 7.2, 7.2, 7.3 and 7.4 Gy, respectively). Especially, in the case of a large HR-CTV volume (≥35 cm(3)) at first ICBT, the total HR-CTV D90 of the adaptive dose group with brachytherapy was significantly higher than that of the standard dose group. There were no significant differences in total D2cc in bladder and rectum between the two groups. Image-guided adaptive brachytherapy based on interfractional tumor volume change improves the dose to the HR-CTV while keeping rectal and bladder doses within acceptable levels.

Changes in bone mineral density in uterine cervical cancer patients after radiation therapy

PURPOSE

To prospectively investigate the changes in bone mineral density (BMD) after pelvic radiation therapy in patients with uterine cervical cancer.

METHODS AND MATERIALS

Of 52 cervical cancer patients who received pelvic RT in our university hospital between 2009 and 2011, 46 patients without recurrence and who were followed up for more than 12 months were included in the study. The BMD of the irradiated region and nonirradiated regions, serum estradiol, tartrate-resistant acid phosphatase-5b, and N-terminal cross-linking telopeptide of collagen 1 were measured before, at 3 months after, and at 12 months after RT. The patient cohort was divided into 2 groups according to estradiol level before RT, and the groups were defined as postmenopausal (<40 pg/mL) and premenopausal (≥40 pg/mL).

RESULTS

The mean BMDs within the irradiation field (lumbar vertebra 5) in the postmenopausal and the premenopausal groups were 0.825 and 0.910 g/cm(2) before RT and 0.746 and 0.841 g/cm(2) 12 months after RT, respectively. Significant decreases were observed in both groups (P<.05 and P<.01, respectively). In addition, in the premenopausal group the mean BMDs of the nonirradiated regions at thoracic vertebrae 9-12 and lumbar vertebrae 2-4 were 0.753 and 0.958 g/cm(2) before RT and were significantly decreased to 0.706 and 0.921 g/cm(2) 12 months after RT (P<.01 and P<.05, respectively). Estradiol significantly decreased 3 months after RT, whereas tartrate-resistant acid phosphatase-5b and N-terminal cross-linking telopeptide of collagen 1 continued to increase over time in the premenopausal group.

CONCLUSIONS

A decrease in BMD in the irradiated region after RT was observed within 1 year, regardless of menopausal status. Furthermore, in premenopausal patients, pelvic RT caused a decrease in systemic BMD.

Comparison of dose-volume analysis between standard Manchester plan and magnetic resonance image-based plan of intracavitary brachytherapy for uterine cervical cancer

To investigate the feasibility of image-based intracavitary brachytherapy (IBICBT) for uterine cervical cancer, we evaluated the dose-volume histograms (DVHs) for the tumor and organs at risk (OARs) and compared results from the IBICBT plan and the standard Manchester system (Manchester plan) in eight patients as a simulation experiment. We performed magnetic resonance imaging (MRI) and computed tomography (CT) following MRI-adapted applicator insertion, then superimposed MR images on the planning CT images to describe the contours of high-risk clinical target volume (HR CTV) and OARs. The median volume of HR CTV was 29 cm(3) (range, 21-61 cm(3)). Median D90 (HR CTV) and V100 (HR CTV) were 116.1% prescribed doses (PD) (90.0-150.8%) and 96.7% (84.2-100%), respectively, for the Manchester plan. In comparison, we confirmed that the median D90 (HR CTV) was 100% PD in the IBICBT plan for all patients. Mean D(2cc) (bladder) was 101.8% PD for the Manchester plan and 83.2% PD for the IBICBT plan. Mean D(2cc) (rectum) was 80.1% PD for the Manchester plan and 64.2% PD for the IBICBT plan. Mean D(2cc) (sigmoid) was 75% PD for the Manchester plan and 57.5% PD for the IBICBT plan. One patient with a large tumor (HR CTV, 61 cm(3)) showed lower D90 (HR CTV) with the Manchester plan than with the IBICBT plan. The Manchester plan may represent overtreatment for small tumors but insufficient dose distribution for larger tumors. The IBICBT plan could reduce OAR dosage while maintaining adequate tumor coverage.

Long-term results of curative intraluminal high dose rate brachytherapy for endobronchial carcinoma

BACKGROUND

The treatment strategy of central lung tumors is not established. Intraluminal brachytherapy (ILBT) is widely used for palliative treatment of endobronchial tumors, however, it is also a promising option for curative treatment with limited data. This study evaluates the results after ILBT for endobronchial carcinoma.

METHOD

Sixteen-endobronchial carcinoma of 13 patients treated with ILBT in curative intent for 2000 to 2008 were retrospectively reviewed. ILBT using high dose rate 192 iridium thin wire system was performed with 5 Gy/fraction at mucosal surface. The patient age ranged from 57 to 82 years old with median 75 years old. The 16 lesions consisted of 13 central endobronchial cancers including 7 roentgenographically occult lung cancers and 3 of tracheal cancers. Of them, 10 lesions were treated with ILBT of median 20 Gy combined with external beam radiation therapy of median 45 Gy and 6 lesions were treated with ILBT alone of median 25 Gy.

RESULTS

Median follow-up time was 32.5 months. Two-year survival rate and local control rate were 92.3% and 86.2%, respectively. Local recurrences were observed in 2 lesions. Three patients died due to lung cancer (1 patient) and intercurrent disease (2 patients). Complications greater than grade 2 were not observed except for one grade 3 dyspnea.

CONCLUSIONS

ILBT combined with or without EBRT might be a curative treatment option in inoperable endobronchial carcinoma patients with tolerable complication.

Impact of 3D image-based PDR brachytherapy on outcome of patients treated for cervix carcinoma in France: results of the French STIC prospective study

PURPOSE

In 2005 a French multicentric non randomized prospective study was initiated to compare two groups of patients treated for cervix carcinoma according to brachytherapy (BT) method: 2D vs 3D dosimetry. The BT dosimetric planning method was chosen for each patient in each center according to the availability of the technique. This study describes the results for 705 out of 801 patients available for analysis.

PATIENTS AND METHODS

For the 2D arm, dosimetry was planned on orthogonal X-Rays using low dose rate (LDR) or pulsed dose rate (PDR) BT. For the 3D arm, dosimetry was planned on 3D imaging (mainly CT) and performed with PDR BT. Each center could follow the dosimetric method they were used to, according to the chosen radioelement and applicator. Manual or graphical optimization was allowed.

PATIENTS AND METHODS

Three treatment regimens were defined: Group 1: BT followed by surgery; 165 patients (2D arm: 76; 3D arm: 89); Group 2: EBRT (+chemotherapy), BT, then surgery; 305 patients (2D arm: 142; 3D arm: 163); Group 3: EBRT (+chemotherapy), then BT; 235 patients, (2D arm: 118; 3D arm: 117).

PATIENTS AND METHODS

The DVH parameters for CTVs (High Risk CTV and Intermediate Risk CTV) and organs at risk (OARs) were computed as recommended by GYN GEC ESTRO guidelines. Total doses were converted to equivalent doses in 2Gy fractions (EQD2). Side effects were prospectively assessed using the CTCAEv3.0.

RESULTS

The 2D and 3D arms were well balanced with regard to age, FIGO stage, histology, EBRT dose and chemotherapy. For each treatment regimen, BT doses and volumes were comparable between the 2D and 3D arms in terms of dose to point A, isodose 60 Gy volume, dose to ICRU rectal points, and TRAK.

RESULTS

Dosimetric data in the 3D arm showed that the dose delivered to 90% of the High Risk CTV (HR CTV D90) was respectively, 81.2Gy(α/β10), 63.2Gy(α/β10) and 73.1Gy(α/β10) for groups 1, 2 and 3. The Intermediate Risk (IR) CTV D90 was respectively, 58.5Gy(α/β10), 57.3Gy(α/β10) and 61.7Gy(α/β10) for groups 1, 2 and 3. For the OARs, doses delivered to D2cc ranged 60-70Gy(α/β3) for the bladder, 33-61Gy(α/β3) for the rectum, and 44-58Gy(α/β3) for the sigmoid according to the regimen.

RESULTS

At 24 months, local relapse-free survival was 91.9% and 100% in group 1, 84.7% and 93% in group 2, 73.9% and 78.5% in group 3; grade 3-4 toxicity rate was 14.6% and 8.9% in group 1, 12.5% and 8.8% in group 2, and 22.7% and 2.6% in group 3 for 2D and 3D arm.

CONCLUSION

This multicentric study has shown that 3D BT is feasible and safe in routine practice. It has improved local control with half the toxicity observed with 2D dosimetry. The combined treatment with radiotherapy and surgery was more toxic than definitive radiotherapy. For patients with advanced tumors, it is necessary to improve coverage of target volumes without raising toxicity.

Dose volume analysis of radiotherapy for inoperable patients with stage I-II endometrial carcinoma

This study aims to assess the efficacy and toxicity of definitive radiotherapy for early-stage endometrial carcinoma. The correlation between CT-based dosimetric parameters and clinical outcomes is also evaluated. Between 2002 and 2006, 10 medically inoperable patients with T1-2 endometrial carcinoma were treated with radiotherapy alone. A combination of external beam radiotherapy (EBRT) and high-dose-rate intracavitary brachytherapy (HDR-ICBT) was used for 9 patients, and one was treated with HDR-ICBT alone. Dose prescription of HDR-ICBT was determined in reference to CT images at brachytherapy, and a total dose of 22-24 Gy in 4 fractions was delivered to the outer perimeter of the uterine corpus. Dose-volume parameters of the gross tumor volume (GTV), clinical target volume (CTV), and organs at risk were assessed retrospectively using the dose-volume histograms derived from the CT image-based treatment planning system. After a median follow-up of 55 months, 9 patients were alive without evidence of recurrence. One patient died from liver cirrhosis 17 months after radiotherapy. Severe acute and late toxicities were not observed in any of the patients. Average minimum dose to 90% of GTV and CTV (D90) was 88.0 and 45.9 Gy(EQD2), respectively. The minimum dose delivered to 2 cc of the most irradiated volumes of the rectum and sigmoid colon (D(2cc)) was 78.9 and 65.9 Gy(EQD2), respectively. These patients developed Grade 1 late complications. In this study, stage I-II endometrial carcinoma was well-controlled locally with minimum late toxicity by radiotherapy alone with HDR-ICBT. 3D image-based brachytherapy may potentially deliver a sufficiently high dose to the whole tumor without significant increase in dose to surrounding normal tissues.

Preliminary results of magnetic resonance imaging-aided high-dose-rate interstitial brachytherapy for recurrent uterine carcinoma after curative surgery

This report presents initial experience with imaging-aided high-dose-rate interstitial brachytherapy (HDR-ISBT) for post-operative recurrence of uterine carcinoma. Fourteen patients presenting with post-operative recurrence of uterine carcinoma (nine cervix and five corpus) between July 2005 and October 2008 were enrolled in this study (median follow-up: 37 months, range: 6-59 months). We implanted magnetic resonance imaging (MRI)-compatible plastic applicators using our own ambulatory technique. HDR-ISBT treatment consisted of twice-a-day irradiation of 6 Gy each with at least a six-hour interval to provide the total prescribed dose. Treatment was based on treatment planning-computed tomography with MRI as a reference. Seven patients were treated with a combination of ISBT (median 30 Gy/5 fractions; range: 27-33 Gy) and external beam radiation therapy (EBRT), and the other seven with brachytherapy only (median 54 Gy/9 fractions; range: 48-54 Gy), one of whom had previously received pelvic EBRT. The three-year estimates of local control and overall survival rates were 77.9% (95% confidence interval (CI): 55.8-100%) and 77.1% (95% CI: 54.2-100%), respectively. Two patients, who had received combined treatment with EBRT showed untoward reactions, including a grade 3 subileus and grade 2 constipation. Another patient, who had been treated with ISBT alone, developed grade 2 urinary constriction. Our imaging-aided HDR-ISBT for post-operative recurrence of uterine carcinoma was found to be practical with promising preliminary results.

Intracavitary combined with CT-guided interstitial brachytherapy for locally advanced uterine cervical cancer: introduction of the technique and a case presentation

We report a new technique of brachytherapy consisting of intracavitary combined with computed tomography (CT)-guided interstitial brachytherapy for locally advanced cervical cancer. A Fletcher-Suit applicator and trocar point needles were used for performing high-dose rate brachytherapy under in-room CT guidance. First, a tandem and ovoids were implanted into the patient's vagina and uterus by conventional brachytherapy method. Based on clinical examination and MRI/CT imaging, operating radiation oncologists decided the positions of insertion in the tumor and the depth of the needles from the upper surface of the ovoid. Insertion of the needle applicator was performed from the vaginal vault inside the ovoid within the tumor under CT guidance. In treatment planning, dwell positions and time adaptations within the tandem and ovoids were performed first for optimization based on the Manchester system, and then stepwise addition of dwell positions within the needle was continued. Finally, dwell positions and dwell weights were manually modified until dose-volume constraints were optimally matched. In our pilot case, the dose of D90 to high-risk clinical target volume was improved from 3.5 Gy to 6.1 Gy by using our hybrid method on the dose-volume histogram. D1cc of the rectum, bladder and sigmoid colon by our hybrid method was 4.8 Gy, 6.4 Gy and 3.5 Gy, respectively. This method consists of advanced image-guided brachytherapy that can be performed safely and accurately. This approach has the potential of increasing target coverage, treated volume, and total dose without increasing the dose to organs at risk.

Current advancement in radiation therapy for uterine cervical cancer

Radiation therapy is one of the effective curative treatments for uterine cervical cancer. However poor clinical results for the advanced stages require further improvement of the treatment. Intensive studies on basic and clinical research have been made to improve local control, primarily important for long term survival in radiation therapy. Regarding current advancement in radiation therapy for uterine cervical cancer, the following three major subjects are pointed out; technological development to improve dose distribution by image guided radiation therapy technology, the concomitant anticancer chemotherapy with combination of radiation therapy, and radiation biological assessment of the radiation resistance of tumors. The biological factors overviewed in this article include hypoxia relating factors of HIF-1alpha, SOD, cell cycle parameters of pMI, proliferation factors of Ki67, EGFR, cerbB2, COX-2, cycle regulation proteins p53, p21, apoptosis regulation proteins Bcl2 and Bax and so on. Especially, the variety of these radiation biological factors is important for the selection of an effective treatment method for each patient to maximize the treatment benefit.