Clinical outcomes of adaptive intracavitary and interstitial brachytherapy technique in locally advanced cervical cancer: A real-world data.

PURPOSE: To evaluate clinical outcomes of CT-based adaptive intracavitary and interstitial brachytherapy (IC followed by IC-ISBT) in locally advanced cervical cancer (LACC) in resource-constrained settings. METHODS AND MATERIALS: LACC patients treated with adaptive brachytherapy techniques were analyzed to evaluate treatment characteristics and clinical outcomes. The Kaplan-Meier method was used for survival analysis, and the log-rank test for univariate analysis. RESULTS: Out of 141 eligible patients with LACC, 87 (61.7%) patients received external beam radiotherapy (EBRT) in referral hospitals, while 54 (38.3%) were treated at our center. We divided our cohort into two groups: poor EBRT responder group (n = 70 [49.6%]) where IC-ISBT was adapted to achieve optimum tumor doses and OAR optimization group 71 (50.4%) where IC-ISBT was performed to reduce OAR doses. Median HRCTV-D90 dose was 88 Gy (range 70-109 Gy) with median HRCTV volume 33cc (range 15-96). Median D2cc doses to OARs were 90 Gy (range 70-107), 71 Gy (range 55-105) and 70 Gy (range 47-90) to bladder, rectum and sigmoid, respectively. At median follow-up of 32 months, 3-year local control (LC), locoregional control (LRC), disease-free survival (DFS) and overall survival (OS) were 83%, 75%, 64% and 72%, respectively. Subgroup analysis revealed significantly better outcomes for OAR optimization compared to poor EBRT responders, with 3-year LC (95% vs. 70.1%, p < 0.001), LRC (87.3% vs. 62.7%, p < 0.001), DFS (79.2% vs. 49.4%, p < 0.001), and OS (86.2% vs. 57.4%, p < 0.001) CONCLUSION: In resource-constrained settings, implementation of Adaptive IC-ISBT is a viable alternative for optimizing OAR doses in LACC. However proactive approach employing IC-ISBT for tumor dose-escalation from first fraction of BT is warranted for improving LC in poor EBRT responders.

Clinical Implementation of "Plan of the Day" Strategy in Definitive Radiation Therapy of Cervical Cancer: Online Adaptation to Address the Challenge of Organ Filling Reproducibility.

PURPOSE: Definitive pelvic intensity modulated radiation therapy (IMRT) in cervical cancer is susceptible to geographic miss due to daily positional and volumetric variations in target and organs at risk. Hence, despite evidence of reduced acute and late treatment-related toxicities, implementation of image-guided IMRT (IG-IMRT) with a reasonable safety margin to encompass organ motion is challenging. METHODS AND MATERIALS: In this prospective, nonrandomized phase 2 study, patients with cervical cancer International Federation of Gynecology and Obstetrics (2009) stage IB2-IIIB between the ages of 18 and 65 years were treated with definitive pelvic chemoradiotherapy with a prespecified organ (bladder and rectum) filling protocol. Reproducibility of organ filling was assessed along with the implementation of daily comprehensive adaptive image-guided radiotherapy (IGRT), with a library of 3 IMRT (volumetric modulated arc therapy) plans with incremental expansions of clinical target volume (CTV) to planning target volume (PTV) (primary) margins (small, 0.7 cm; adequate, 1 cm; and large, 1.5 cm) and a backup motion robust 3-dimensional conformal radiotherapy plan; the appropriate plan is chosen based on pretreatment cone beam computed tomography (CBCT) ("plan of the day" approach). RESULTS: Fifty patients with a median age of 49 years (IQR, 45-56 years) received definitive radiation therapy (45-46 Gy in 23-25 fractions to pelvis, with simultaneous integrated boost to gross nodes in 15 patients) with the aforementioned IGRT protocol. In the analysis of 1171 CBCT images (in 1184 treatment sessions), the mean planning computed tomography (CT) and CBCT bladder volumes were 417 and 373 cc, respectively. Significant interfractional variation in bladder volume was noted with a mean absolute dispersion of 29.5% with respect to planning CT; significant influential random factors were postchemotherapy sessions (P ≤ .001), pre-CBCT protocol duration (P = .001), and grades of chemotherapy induced nausea vomiting (P = .001). Significantly higher variation in bladder filling was noted in patients with older age (P = .014) and larger planning CT bladder volume (P ≤ .001). Time trend analysis of fraction-wise bladder volume revealed an absolute systemic reduction of 16.3% in bladder volume means from the first to the fifth week. Variation in rectal diameter was much less pronounced, with 19.2% mean dispersion and without any significant factors affecting it. Although in 19% and 2% of sessions large IMRT PTV and 3-dimensional conformal radiotherapy were necessary to cover the primary target, respectively, reduction in treated volume was possible in 43% of sessions with small PTV selection instead of standard adequate PTV (36% sessions). Plan of the day selection had a moderate to strong correlation with nonabsolute dispersion of bladder filling (Spearman ρ =0.4; P = .001) and a weak (but significant) correlation with grades of acute toxicities. The planned protocol was well tolerated with no radiation-induced local grade 3 toxicity. CONCLUSIONS: Interfractional variation in organ filling (especially bladder) is inevitable despite fixed pretreatment protocol in definitive settings (intact cervix). Despite the logistical challenges, adaptive IGRT in the form of plan of the day based on incremental CTV-to-PTV margins is a relatively simple and feasible strategy to minimize geometric uncertainties in radical IG-IMRT of cervical cancer.

Sigmoid dose accumulation and reporting for multifractionated brachytherapy for cervical cancer: Methodological development of sigmoid points through virtual endoscopic method.

PURPOSE: The sigmoid is an important organ at risk for gynecological brachytherapy (BT). However, the reliability of localization of high-dose regions during multi-fractionated treatment is limited. This work reports the methodological development of sigmoid points to summate multi-fractionated doses. METHODS AND MATERIAL: Ten paired MRI data sets of ring-based intracavitary brachytherapy were obtained. Simulating a virtual endoscope, a reference line was created along the central axis of the anorectosigmoid for each implant. A trendline was generated, and linear dose was determined. Three-dimensional (3D) coordinates of high-dose regions were identified, and overlap was determined. In the next step, 3D coordinates of high-dose sigmoid points were localized in reference to cervical os and re-verified for location in reference to sigmoid lumen and corroboration with 2cc doses. With minor modifications, sigmoid points were proposed. RESULTS: In 6 of 10 patients, high-dose regions co-localized in subsequent fractions of BT. Three high-dose regions were identified along the sigmoid length and proposed as sigmoid points in reference to cervical os. (S1'= 0.5 cm right, 1.5 cm posterior, and 2.4 cm cranial; S2' = 0.3 cm anterior and 4.5 cm cranial; S3' = 2.7 cm left, 3 cm anterior, and 3.6 cm cranial to the cervical os). S1' and S2' were located in the sigmoid in 70% and 60% of data sets. The mean difference between D2cc and S1'/S2' was 0.30 Gy and 1.06 Gy respectively. S3' had limited corroboration to sigmoid lumen or 2 cc doses. The points S1' and S2' were further modified (minor) for applicability and proposed as sigmoid points 1 and 2 (SP1 0.5 right,1.5 posterior and 2.5 cm cranial to cervical os and SP2 (0.5 cm anterior and 4.5 cm cranial to cervical os)). CONCLUSION: SP1 and SP 2 are proposed as a surrogate for 2 cc sigmoid doses and may provide a method of reliable inter-fraction dose summation. This pilot work requires further validation.

Early outcomes of abbreviated multi-fractionated brachytherapy schedule for cervix cancer during COVID-19 pandemic.

PURPOSE: Brachytherapy (BT) for cervix cancer was listed as a level I priority and reduced number of implants and multiple fractions were recommended during COVID-19 pandemic. We present early clinical outcome of this approach. METHODS AND MATERIALS: Patients treated with (chemo)radiotherapy and BT with single implant and multiple fractions BT were included. Treatment protocol included 3-5 fractions of 5-8.5 Gy with an aim to achieve point A dose of 70 Gy EQD210Gy (or HRCTV dose of >80 Gy EQD210Gy) in those undergoing intracavitary (IC) and HRCTV dose >85 Gy EQD2 10Gy in patients undergoing Intracavitary-Interstitial (IC/IS) whereas maintaining bladder (B2cc), rectum (R2cc), sigmoid (S 2cc) doses of 90, 75, and 75 Gy EQD23Gy. Time to event analysis was used to report oncological endpoints. Toxicity was reported using crude proportions. RESULTS: From April 2020 to March, 2021, 64 patients with stage IB2-IV received single implant and multi-fraction BT after external radiation of 45 Gy/25 fractions/5 weeks. Only 76.7% (n = 49) received concurrent chemotherapy. Median overall treatment time (OTT) was 56 days (38-131 days). Overall, 62.5% (n = 40) patients received IC and 37.5% (n = 24) received IC+IS. The median HRCTV was 34.7 cc (IQR 25-41). Median (IQR) point A dose, HRCTV D90, B2cc, R2cc, and S2cc for those undergoing IC was 74 Gy (71-78), 80 Gy (73-84), 86 Gy (82-89), 70 Gy (65-74), 65 Gy (59-73) respectively. For the IC+IS cohort, HRCTV D90, B2cc, R2cc, and S2cc was 84 Gy (78-89 Gy), 89 Gy (86-92), 70 Gy (67-74), 68 Gy (59-76). At a median follow-up of 16 months (5-27) the 2-year local control, pelvic control, cause specific and overall survival was 88%, 85.3%, 92.2%, and 81.3% respectively. Late gastrointestinal and genitourinary grade ≥III toxicities were 14% and 1.5% each. CONCLUSIONS: Abbreviated BT outcomes are encouraging for oncological outcomes despite delays in overall treatment time and omission of chemotherapy. Further mature follow up is needed.

Patterns of Relapse After Adjuvant Chemoradiation for Cervical Cancer in a Phase 3 Clinical Trial (PARCER): An Evaluation of Updated NRG Oncology/RTOG Target Delineation Guidelines.

PURPOSE: The Radiation Therapy Oncology Group (RTOG) under NRG Oncology recently published updated contouring guidelines for intensity modulated radiation therapy in postoperative treatment for endometrial and cervical cancer. The present study was designed to evaluate the implications of newly published guidelines. METHODS AND MATERIALS: We recruited 300 patients in a phase 3 randomized controlled trial of adjuvant chemoradiation therapy for cervical cancer (NCT01279135) to understand patterns of relapse. For those patients with pelvic relapse, we imported radiation therapy structure sets, treatment plans, and diagnostic images at relapse on the treatment planning system. We performed rigid registration with treatment planning images that contained the delineated planning target volume and radiation dose information. We delineated gross tumor volume at time of relapse on the diagnostic scans and superimposed it on the radiation therapy treatment scans. We categorized the site of pelvic relapse as "within field of old RTOG/[Postoperative Adjuvant Radiation in Cervical Cancer (PARCER)] target delineation guidelines" or "within field of new NRG/RTOG guidelines," or both, and compared proportions of recurrences contained within the 2 guidelines. We consider a P value of <.05 statistically significant. Additionally, we generated intensity modulated radiation therapy treatment plans based on the new guidelines for a limited set of patients to see if these new guidelines increased the organ at risk doses. RESULTS: Most common form of relapse was distant metastasis (15%). Pelvic relapse rate in our study was 8%. Overall, 9 out of 19 relapses were encompassed in the contouring guidelines of the old RTOG/ Postoperative Adjuvant Radiation in Cervical Cancer (PARCER) trial, and 12 out of 19 were encompassed within the new RTOG 2021 contouring guidelines. This corresponded to a further 1% reduction in local relapses (P = .007). Dose to rectum was marginally increased with the new contouring, with no difference in other organs at risk. Salvage treatment was offered in 25 out of 60 patients who relapsed. Patients who received local treatment after relapse had a mean survival after relapse of 27.2 months compared with 8 months among those who received supportive care alone. CONCLUSIONS: Our study supports the use of newly published NRG/RTOG contouring guidelines in patients with cervical cancer who have undergone hysterectomy. Further data are needed to ascertain if anterior extension of the clinical target volume is needed as in the Postoperative Adjuvant Radiation in Cervical Cancer trial.

Clinical outcomes of patients treated with template-based high-dose-rate interstitial brachytherapy boost for post-operative recurrent gynecological malignancies: A retrospective analysis.

Purpose: To report the clinical outcomes in patients treated with Martinez universal perineal interstitial template (MUPIT)-based interstitial brachytherapy boost for primary and recurrent vault and vaginal cancers, and to perform a comparative analysis with our previously published series of similar patients. Material and methods: One hundred and seventeen patients treated between January, 2009 and December, 2015 were evaluated. Descriptive statistics for the patterns of relapse, local recurrence-free survival (LRFS), disease-free survival (DFS), overall survival (OS), and late toxicities were carried out. Kaplan-Meier curves were used for survival analysis. All variables with the potential to affect outcomes were tested using log-rank test for statistical significance. Results: At a median follow-up of 63 months, LRFS, DFS, and OS at 3/5 years were 77.1%/74.7%, 61%/52%, and 72.3%/63.1%, respectively. Overall treatment time (OTT) of 56 days did not affect outcomes. Bulky tumors and OTT > 63 days adversely affected LRFS. Overall treatment time also significantly impacted DFS and OS. Grade 3-4 late bladder toxicities were observed in 1.7% patients, and grade 3-4 late rectal toxicities in 5% patients. Compared to our previous series, the outcome in the current series is better in terms of severe late toxicities (5% improvement in rectal toxicity, and 2.7% improvement in bladder toxicity) and OS by 10%. This could be attributed to the increasing use of concurrent chemotherapy and relative optimization strategies for organs at risk. Conclusions: Patients with primary and recurrent vault and vaginal cancers treated with high-dose-rate interstitial brachytherapy boost using MUPIT resulted in modest clinical outcomes and acceptable late toxicities. OTT was the most important factor affecting the outcomes.

Quality Improvement Process with Incident Learning Program Helped Reducing Transcriptional Errors on Telecobalt Due to Mismatched Parameters in Different Generations.

Purpose: Higher frequency of transcriptional errors in the radiotherapy electronic charts for patients on telecobalt was noted. We describe the impact of the quality improvement (QI) initiative under the department's incident learning program (ILP). Materials and Methods: The multidisciplinary quality team under ILP was formed to identify the root cause and introduce methods to reduce (smart goal) the current transcription error rate of 40% to <5% over 12 months. A root cause analysis including a fishbone diagram, Pareto chart, and action prioritization matrix was done to identify key drivers and interventions. Plan-Do-Study-Act (PDSA) Cycle strategy was undertaken. The primary outcome was percentage charts with transcriptional errors per month. The balancing measure was "new errors" due to interventions. All errors were identified and corrected before patient treatment. Results: The average baseline error rate was 44.14%. The two key drivers identified were education of the workforce involved and mechanical synchronization of various machine parameters. PDSA cycle 1 consisted of an education program and sensitization of the staff, post which the error rates dropped to 5.4% (t-test P = 0.03). Post-PDSA cycle 2 (synchronization of machine parameters), 1, 3, and 6 months and 1 year, the error rates were sustained to 5%, 4%, 3%, and 4% (t-test P > 0.05) with no new additional errors. Conclusions: With various generations of machines and technologies that are not synchronized, the proneness of transcription errors can be very high which can be identified and corrected with a typical QI process under ILP.

Effect of COVID-19 Pandemic on Gynecological Cancer Radiation During Complete Nationwide Lockdown: Observations and Reflections From Tertiary Care Institute in India.

PURPOSE: To report real-world compliance to radiation in gynecologic cancers during the complete lockdown phase of COVID-19 pandemic. METHODS AND MATERIALS: From March 23, 2020, until June 30, 2020, complete lockdown was imposed in India. During this period there was restructuring of cancer care and radiation oncology department due to operational policies prevalent in the institution, and the care for gynecological cancer was based on the evolving international recommendations. Institutional review board approval was obtained to audit patterns of care during the complete lockdown phase. Descriptive variables were used to report on patient characteristics, compliance, delays, toxicity, and observed deviations in recommended care. RESULTS: During the lockdown period spanning 100 days, treatment of 270 and telephonic follow-up of 1103 patients with gynecological cancer was undertaken. Of 270 new patients, due to travel restrictions, 90 patients were referred to the facilities in vicinity of their residence. Of the remaining 180 patients, 138 were planned for complete treatment at our institution and 42 were referred to our center for brachytherapy. Of 138 patients, only 106 (76%) completed the planned external radiation. Twenty-four (26%) patients completed full course of concurrent chemotherapy, 11 (12%) received chemotherapy dose reduction, and 57 (62%) received no concurrent chemotherapy. Treatment delay of up to 3 weeks was noted in 8.6% patients due to COVID-19 infection. No grade 4 to 5 acute sequelae were observed. No excess adverse effects were observed in high-risk population. Low rate of symptom burden was observed among 1103 patients on telephonic follow-up. With 100 (9.6%) patients reporting symptoms, among these, 54% (54 of 100) had complete resolution of symptoms within 4 weeks of teleconsultation, and 10% had disease progression. CONCLUSIONS: Low compliance with planned treatment was observed for radiation and concurrent chemotherapy due to lockdown and fear of contracting COVID-19 and will likely lead to increased risk of cancer-related mortality. Rapid restructuring of care is needed to prevent the same as COVID-19 pandemic further evolves.

Modified Houdek vault applicator for high-dose-rate brachytherapy: a technical report and case series.

PURPOSE: Treatment of isolated post-surgical vault recurrence of cervical and endometrial cancers in previously unirradiated patients includes external beam radiotherapy (EBRT) ± concomitant chemotherapy, followed by brachytherapy (BT) boost. Supra-vaginal component of vault disease often requires interstitial BT for optimal dose coverage. We describe technical details and preliminary case series using modified Houdek vault applicator (MHVA) developed at our institution for limited intra-cavitary plus interstitial high-dose-rate (HDR) vault BT. MATERIAL AND METHODS: Nineteen patients with vaginal vault recurrences received BT boost with MHVA between October 2015 and May 2018. All underwent BT application and CT-based BT planning after completion of EBRT ± concomitant chemotherapy. RESULTS: Median EQD2 of BT dose in patients with carcinoma cervix recurrence (n = 15, α/ß = 10) was 18.8 Gy, and in those with endometrial cancer recurrence was 22.08 Gy (n = 4, α/ß = 4.5). Median total EQD2 was 68.8 Gy and 72.08 Gy, respectively. Mean 2 cc of bladder, rectum, and sigmoid EBRT + BT doses (EQD2, α/ß = 3) were 65.38 Gy (±7.76), 63.37 Gy (±5.52), and 57.04 Gy (±4.45), respectively. At 6-8 weeks, 17 patients showed complete response (CR). With median follow-up of 20.5 months, 2-year overall survival was 95% (95% CI: 85.2-100.0%), and 2-year progression-free survival was 79.4% (95% CI: 61.0-97.8%). Late toxicities seen were grade 2 proctitis in 1 patient, grade 1 proctitis in 5, grade 2 urethritis in 1, grade 3 cystitis in 1, and recto-vaginal fistula in 1 patient (with disease controlled). Recurrence rate was 6.7 times higher in patients with post-EBRT disease greater than 10 mm (p = 0.01). CONCLUSIONS: MHVA is a simple solution for intra-cavitary and interstitial HDR-BT boost in isolated vault cancers post-surgery, achieving acceptable dosimetric parameters. Preliminary clinical outcomes and late toxicities are satisfactory.

What is the dosimetric impact of isotropic vs anisotropic safety margins for delineation of the clinical target volume in breast brachytherapy?

PURPOSE: The purpose of the study was to report dosimetric differences for breast brachytherapy plans optimized for clinical target volume (CTV) generated using conventional isotropic expansion of tumor bed volume (TBV) and Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology (GEC-ESTRO) recommendations to expand the TBV anisotropically to achieve a total safety margin of 2 cm (resection margin size + added safety margin). METHODS: Institutional records of 100 patients who underwent accelerated partial breast irradiation using multicatheter interstitial brachytherapy from May 2015 to March 2020 were reviewed retrospectively. Two sets of CT-based plans were made, one with 1-cm isotropic margins around the tumor bed (CTV_ISO) and the other with anisotropic margins (CTV_GEC). Plans were evaluated and compared using the American Brachytherapy Society and GEC-ESTRO guidelines. RESULTS: The median TBV was 36.97 cc. The median margin widths were as follows: anterior 1.2, posterior 1.0, superior 1.0, inferior 0.9, medial 1.2, and lateral 1.2 cm. The mean tumor bed coverage index was 0.94; 0.93 [p.066], the CTV coverage index 0.86; 0.84 [p 0.001], the dose homogeneity index (DHI) 0.77; 0.75 [p < 0.001] and the conformity index 0.66; 0.64 [p < 0.001] in CTV_ISO and CTV_GEC plans, respectively. In smaller volume implants (TBV< 35 cc), the DHI was 0.76; 0.75 [p 0.008] and the conformity index was 0.66; 0.62 [p < 0.001], whereas in larger volumes >35 cc, the CTV coverage index was 0.86; 0.84 [p 0.003] and the DHI 0.78; 0.76 [p 0.001] in CTV_ISO and CTV_GEC plans, respectively. CONCLUSIONS: In this cohort of patients who underwent accelerated partial breast irradiation, plans with anisotropic margins had lower conformity, the impact of which was predominantly seen in smaller implants. Rest of the dosimetric constraints were achieved in both the plans as per the American Brachytherapy Society and GEC-ESTRO guidelines.