Target tailoring and proton beam therapy to reduce small bowel dose in cervical cancer radiotherapy : A comparison of benefits

Exclusion of non-Involved uterus from the target volume (EXIT-trial): An individualized treatment for locally advanced cervical cancer using modern radiotherapy and imaging techniques followed by completion surgery

Background and purpose

Chemoradiotherapy followed by brachytherapy is the standard of care for locally advanced cervical cancer (LACC). In this study, we postulate that omitting an iconographical unaffected uterus (+12 mm distance from the tumour) from the treatment volume is safe and that no tumour will be found in the non-targeted uterus (NTU) leading to reduction of high-dose volumes of surrounding organs at risk (OARs).

Material and Methods

In this single-arm phase 2 study, two sets of target volumes were delineated: one standard-volume (whole uterus) and an EXIT-volume (exclusion of non-tumour-bearing parts of the uterus with a minimum 12 mm margin from the tumour). All patients underwent chemoradiotherapy targeting the EXIT-volume, followed by completion hysterectomy. In 15 patients, a plan comparison between two treatment plans (PTV vs PTV_EXIT) was performed. The primary endpoint was the pathological absence of tumour involvement in the non-targeted uterus (NTU). Secondary endpoints included dosimetric impact of target volume reduction on OARs, acute and chronic toxicity, overall survival (OS), locoregional recurrence-free survival (LRFS), and progression-free survival (PFS).

Results

In all 21 (FIGO stage I: 2; II: 14;III: 3; IV: 2) patients the NTU was pathologically negative. Ssignificant reductions in Dmean in bladder, sigmoid and rectum; V15Gy in sigmoid and rectum, V30Gy in bladder, sigmoid and rectum; V40Gy and V45Gy in bladder, bowel bag, sigmoid and rectum; V50Gy in rectum were achieved. Median follow-up was 54 months (range 7-79 months). Acute toxicity was mainly grade 2 and 5 % grade 3 urinary. The 3y- OS, PFS and LRFS were respectively 76,2%, 64,9% and 81 %.

Conclusion

MRI-based exclusion of the non-tumour-bearing parts of the uterus at a minimum distance of 12 mm from the tumour out of the target volume in LACC can be done without risk of residual disease in the NTU, leading to a significant reduction of the volume of surrounding OARS treated to high doses.

Acute and long-term toxicity of whole pelvis proton radiation therapy for definitive or adjuvant management of gynecologic cancers

OBJECTIVE

To characterize long-term toxicity and disease outcomes with whole pelvis (WP) pencil beam scanning proton radiation therapy (PBS PRT) for gynecologic malignancies.

METHODS

We reviewed 23 patients treated from 2013 to 2019 with WP PBS PRT for endometrial, cervical, and vaginal cancer. We report acute and late Grade (G)2+ toxicities, graded by Common Terminology Criteria for Adverse Events, Version 5. Disease outcomes were assessed by Kaplan-Meier method.

RESULTS

Median age was 59 years. Median follow up was 4.8 years. 12 (52.2%) had uterine cancer, 10 (43.5%) cervical, 1 (4.3%) vaginal. 20 (86.9%) were treated post-hysterectomy. 22 (95.7%) received chemotherapy, 12 concurrently (52.2%). The median PBS PRT dose was 50.4GyRBE (range, 45-62.5). 8 (34.8% had para-aortic/extended fields. 10 (43.5%) received brachytherapy boost. Median follow up was 4.8 years. 5-year actuarial local control was 95.2%, regional control 90.9%, distant control 74.7%, both disease control and progression-free survival 71.2%. Overall survival was 91.3%. In the acute period, 2 patients (8.7%) had G2 genitourinary (GU) toxicity, 6 (26.1%) had gastrointestinal (GI) G2-3 toxicity, 17 (73.9%) had G2-4 hematologic (H) toxicity. In the late period, 3 (13.0%) had G2 GU toxicity, 1 (4.3%) had G2 GI toxicity, 2 (8.7%) had G2-3H toxicity. The mean small bowel V15Gy was 213.4 cc. Mean large bowel V15 Gy was 131.9 cc.

CONCLUSIONS

WP PBS PRT for gynecologic malignancies delivers favorable locoregional control. Rates of GU and GI toxicity are low. Acute hematologic toxicity was most common, which may be related to the large proportion of patients receiving chemotherapy.

A modified delineation method of para-aortic nodal clinical target volume in patients with locally advanced cervical cancer

PURPOSE

To validate the nodal center coverage (NCC) of the three mainstream delineation methods of para-aortic nodal clinical target volume (CTV) and propose a modified delineation method of para-aortic nodal CTV in prophylactic extended-field irradiation (EFI) of cervical cancer.

METHODS

A total of 106 patients with para-aortic lymph nodes (PALNs) identified on PET/CT were included at Peking Union Medical College Hospital between 2011 and 2020. PALNs were classified as left lateral para-aortic (LLPA), aorto-caval (AC), and right para-caval (RPC). Distances from the nodal center to the aorta and inferior vena cava (IVC) were measured. The NCC of the three mainstream delineation methods of para-aortic nodal CTV (CTV-K, CTV-S, and CTV-D) and a modified CTV (CTV-M) was calculated. Radiotherapy plans were created based on 4 CTVs for 10 selected patients who received prophylactic EFI. The chi-squared test and the Student's t-test were performed.

RESULTS

We identified 344 PALNs (216 LLPA, 101 AC, and 27 RPC) in 106 patients. Mean distance from the nodal center to the aorta was 9.6 mm in the LLPA and 7 mm in the AC and from the nodal center to the IVC was 5.6 mm in the AC and 5.6 mm in the RPC. CTV-D improved the NCC of 98% compared with 92% for CTV-K (p = 0.002) and 95% for CTV-S (p = 0.046). CTV-M provided the same satisfactory NCC as CTV-D (97% vs. 98%, p = 0.485). The V_50Gy to the duodenum, the D_mean to the bilateral kidneys, and the V_45Gy to the small bowel were significantly lower on the CTV-M-based plan than on the CTV-D-based plan (p = 0.001, 0.011, and 0.001, respectively).

CONCLUSION

CTV-D provided more satisfactory NCC than CTV-K and CTV-S. CTV-M provided the same satisfactory NCC as CTV-D and reduced the dose to the critical structures.

Advances in management of locally advanced cervical cancer

Globally, cervical cancer has the fourth highest cancer incidence and mortality in women. Cervical cancer is unique because it has effective prevention, screening, and treatment options. This review discusses the current cervical cancer advances with a focus on locally advanced cervical cancer. Topics discussed include diagnostic imaging principles, surgical management with adjuvant therapy and definitive concurrent chemoradiotherapy. Emphasis is given on current advances and future research directions in radiation therapy (RT) with an emphasis on three-dimensional brachytherapy, intensity-modulated RT, image-guided RT, proton RT and hyperthermia.

Conventional 3D conformal radiotherapy and volumetric modulated arc therapy for cervical cancer: Comparison of clinical results with special consideration of the influence of patient- and treatment-related parameters

PURPOSE

Intensity-modulated radiotherapy (IMRT) for cervical cancer yields favorable results in terms of oncological outcomes, acute toxicity, and late toxicity. Limited data are available on clinical results with volumetric modulated arc therapy (VMAT). This study's purpose is to compare outcome and toxicity with VMAT to conventional 3D conformal radiotherapy (3DCRT), giving special consideration to the influence of patient- and treatment-related parameters on side effects.

MATERIALS AND METHODS

Patients with cervical cancer stage I-IVA underwent radiotherapy alone or chemoradiotherapy using 3DCRT (n = 75) or VMAT (n = 30). Survival endpoints were overall survival, progression-free survival, and locoregional control. The National Cancer Institute Common Terminology Criteria for Adverse Events and the Late Effects of Normal Tissues criteria were used for toxicity assessment. Toxicity and patient- and treatment-related parameters were included in a multivariable model.

RESULTS

There were no differences in survival rates between treatment groups. VMAT significantly reduced late small bowel toxicity (OR = 0.10, p = 0.03). Additionally, VMAT was associated with an increased risk of acute urinary toxicity (OR = 2.94, p = 0.01). A low body mass index (BMI; OR = 2.46, p = 0.03) and overall acute toxicity ≥grade 2 (OR = 4.17, p < 0.01) were associated with increased overall late toxicity.

CONCLUSION

We demonstrated significant reduction of late small bowel toxicity with VMAT treatment, an improvement in long-term morbidity is conceivable. VMAT-treated patients experienced acute urinary toxicity more frequently. Further analysis of patient- and treatment-related parameters indicates that the close monitoring of patients with low BMI and of patients who experienced relevant acute toxicity during follow-up care could improve late toxicity profiles.

Rectal Dose Is the Other Dosimetric Factor in Addition to Small Bowel for Prediction of Acute Diarrhea during Postoperative Whole-Pelvic Intensity-Modulated Radiotherapy in Gynecologic Patients

Simple Summary

Although the small bowel volume effect for acute diarrhea during radiotherapy has been investigated, no study has reported the influence of rectal dose. We analyzed 108 patients undergoing intensity-modulated radiotherapy after hysterectomy. Acute diarrhea was defined as onset during radiotherapy based on Common Terminology Criteria for Adverse Events (CTCAE) version 3. Both small bowel and rectum dosimetric parameters affected Grade 2 to 3 diarrhea. The high-dose volume effects on the small bowel still play an important role in postoperative intensity-modulated radiotherapy. This is the first large cohort study to demonstrate the role of both IMRT dosimetric factors of the rectum and the small bowel in acute diarrhea in gynecological patients with a previous hysterectomy. A small bowel volume of 39.6 Gy < 60 mL and a mean rectal dose of <32.75 Gy are suggested as constraints to treatment planning.

Abstract

We studied the association of rectal dose with acute diarrhea in patients with gynecologic malignancies undergoing whole-pelvic (WP) intensity-modulated radiotherapy (IMRT). From June 2006 to April 2019, 108 patients with previous hysterectomy who underwent WP IMRT were enrolled in this cohort study. WP irradiation of 39.6–45 Gy/22–25 fractions was initially delivered to the patients. Common Terminology Criteria for Adverse Events (CTCAE) version 3 was used to evaluate acute diarrhea during radiotherapy. Small bowel volume at different levels of isodose curves (Vn%) and mean rectal dose (MRD) were measured for statistical analysis. The multivariate analysis showed that the MRD ≥ 32.75 Gy (p = 0.005) and small bowel volume of 100% prescribed (V100%) ≥ 60 mL (p = 0.008) were independent factors of Grade 2 or higher diarrhea. The cumulative incidence of Grade 2 or higher diarrhea at 39.6 Gy were 70.5%, 42.2%, and 15.0% (p < 0.001) in patients with both high (V100% ≥ 60 mL and MRD ≥ 32.75 Gy), either high, and both low volume-dose factors, respectively. Strict constraints for the rectum/small bowel or image-guided radiotherapy to reduce these doses are suggested.

Dose-Volume Effects and Risk Factors for Late Diarrhea in Cervix Cancer Patients After Radiochemotherapy With Image Guided Adaptive Brachytherapy in the EMBRACE I Study

PURPOSE

To evaluate patient- and treatment-related risk factors associated with incidence and persistence of late diarrhea after radiochemotherapy and image guided adaptive brachytherapy (IGABT) in locally advanced cervical cancer.

MATERIALS AND METHODS

Of 1416 patients from the EMBRACE I study, 1199 were prospectively evaluated using physician-reported (Common Terminology Criteria for Adverse Events version 3 [CTCAEv3]) assessment for diarrhea; median follow-up 48 months. Patient-reported outcome (EORTC) was available in 900 patients. Incidence of CTCAE G≥2, G≥3, and EORTC "very much" diarrhea was analyzed with Cox proportional hazards regression. Binary logistic regression was used for analysis of persistent G≥1 and EORTC "quite a bit" - "very much" (≥"quite a bit") diarrhea, defined if present in at least half of all follow-ups.

RESULTS

Crude incidences of G≥2 and G≥3 diarrhea were 8.3% and 1.5%, respectively, and 8% of patients reported "very much" diarrhea. Persistent G≥1 and ≥"quite a bit" diarrhea was present in 16% and 7%, respectively. Patient-related risk factors were baseline diarrhea, smoking, and diabetes with hazard ratios of 1.4 to 7.3. Treatment-related risk factors included prescribed dose, V43 Gy, V57 Gy (lymph node boost), and para-aortic irradiation for external beam radiation therapy (EBRT). G≥2 diarrhea at 3 years increased from 9.5% to 19.9% with prescribed dose 45 Gy versus 50 Gy, 8.7% to 14.0% with V43 Gy <2500 cm³ versus >3000 cm³ and 9.4% to 19.0% with V57 Gy <165 cm³ versus ≥165 cm³. Brachytherapy-related bowel and rectum D_2cm3 were also associated with diarrhea.

CONCLUSION

Dose and volume effects have been established for late diarrhea after radiochemotherapy and IGABT in both CTCAE and EORTC reporting. The risk of diarrhea was lower with a pelvic EBRT prescription of 45 Gy, and higher with larger lymph node boosts volumes (ie, ≥165 cm³). The importance of EBRT volumes as determinants of late toxicity underline the need for continuous quality assurance of target contouring, dose planning, and conformity. The findings of brachytherapy dosimetric factors related to the intestines may become more important with highly conformal EBRT.

Dosimetric comparison of library of plans and online MRI-guided radiotherapy of cervical cancer in the presence of intrafraction anatomical changes

Background

Online magnetic resonance imaging (MRI)-guided radiotherapy of cervical cancer has the potential to further reduce dose to organs at risk (OAR) as compared to a library of plans (LOP) approach. This study presents a dosimetric comparison of an MRI-guided strategy with a LOP strategy taking intrafraction anatomical changes into account.

Methods

The 14 patients included in this study were treated with chemo radiation at our institute and received weekly MRIs after informed consent. The MRI-guided strategy consisted of treatment plans created on the weekly sagittal MRI with 3 mm and 5 mm planning target volume (PTV) margin for clinical target volume (CTV) cervix-uterus (MRI_3mm and MRI_5mm). The plans for the LOP strategy were based on interpolations of CTV cervix-uterus on pretreatment full and empty bladder scans. Dose volume histogram (DVH) parameters were compared for targets and OARs as delineated on the weekly transversal MRI, which was acquired on average 10 min after the sagittal MRI.

Results

For the MRI_5mm strategy D_98% of the high-risk CTV was at least 95% for all weekly MRIs of all patients, while for the LOP and MRI_3mm strategy this requirement was not satisfied for at least one weekly MRI for 1 and 3 patients, respectively. The average reduction of the volume of the reference dose (95% of the prescribed dose) as compared to the LOP strategy was 464 cm³ for the MRI_3mm strategy, and 422 cm³ for the MRI_5mm strategy. The bowel bag constraint V_40Gy < 350 cm³ was violated for 13 patients for the LOP strategy and for 5 patients for both MRI_3mm and MRI_5mm strategy.

Conclusions

With online MRI-guided radiotherapy of cervical cancer considerable sparing of OARs can be achieved. If a new treatment plan can be generated and delivered within 10 min, an online MRI-guided strategy with a 5 mm PTV margin for CTV cervix-uterus is sufficient to account for intrafraction anatomical changes.

Trial registration

NL44492.018.13.

Electronic supplementary material

The online version of this article (10.1186/s13014-019-1322-0) contains supplementary material, which is available to authorized users.

Prospective validation of craniocaudal tumour size on MR imaging compared to histoPAthology in patients with uterine cervical cancer: The MPAC study

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Tumour extension on MRI was compared with histopathology using three methods.

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MRI visualises tumour extension within a margin of 10 mm compared to microscopy.

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The major source of measurement uncertainty is post-surgical change of organ.

Purpose

To determine the accuracy of MRI in detecting craniocaudal tumour extension, compared to histopathology, of the hysterectomy specimen in patients with early-stage uterine cervical cancer. Three complementary methods were investigated.

Materials and methods

Thirty-four patients with early-stage cervical cancer had pre-operative MRI, followed by radical hysterectomy or trachelectomy. 1) craniocaudal tumour extension was measured on MRI by two radiologists and compared to microscopy by a pathologist, 2) to compensate for changes in uterine shape between pre-operative MRI and the surgical specimen, craniocaudal tumour extensions were directly compared and appreciated as being a part of a 3-dimensional tumour by a radiation oncologist and resident, and 3) tumour size on MRI was compared macroscopically after digital non-rigid registration of the uterus, uterine cavity and tumour of both modalities.

Results

The craniocaudal tumour extension measured on histopathology minus MRI gives: 1) on average +3 mm difference when measured by a radiologist compared to the microscopic extension (range −13 to +15 mm), 2) −0.2 mm (range −11 to +6.0 mm) when evaluated on MRI by a radiation oncologist compared to the macroscopic tumour; 3) after non-rigid organ registration, a margin of 10 mm around the tumour on MRI would be needed to cover 95% of the tumour in 90% of the patients.

Conclusions

Results indicate that microscopic tumour extension towards the uterine fundus is within a margin of 10 mm around the visible tumour on MRI. The major source of measurement uncertainty is post-surgical change of organ shape and form.

Determination of spatial dose distribution in UCC treatments with LDR brachytherapy using Monte Carlo methods

Using Monte Carlos methods, with the MCNP5 code, a gynecological phantom and a vaginal cylinder were modeled. The spatial distribution of absorbed dose rates in Uterine Cervical Cancer treatment through low dose rate brachytherapy was determined. A liquid water gynecology computational phantom, including a vaginal cylinder applicator made of Lucite, was designed. The applicator has a linear array of four radioactive sources of Cesium 137. Around the vaginal cylinder, 13 water spherical cells of 0.5 cm-diameter were modeled to calculate absorbed dose emulating the procedure made by the treatment planning system. The gamma-ray fluence distribution was estimated, as well as the absorbed doses resulting approximately symmetrical for cells located at upper and lower of vaginal cylinder. Obtained results allow the use of the radioactive decay law to determine dose rate for Uterine Cervical Cancer using low dose rate brachytherapy.