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.

Reirradiation with advanced brachytherapy techniques in recurrent GYN cancers.

PURPOSE: To evaluate clinical outcomes of recurrent gynaecological cancers treated with reirradiation (reRT) using advanced brachytherapy (BT) technique. METHODS AND MATERIALS: Seventy-six women who underwent reRT with BT for gynaecological cancers at our institute between January 2000 and December 2019 were analysed to determine patient, disease and treatment characteristics and clinical outcomes. Descriptive analysis was used for demographics, and the Kaplan Meir method was used for survival analysis. RESULTS: Median age at recurrence was 55 years (Range: 35-73). Forty-three patients had recurrent cervical cancer with intact uterus, and 33 had recurrent vault/vaginal cancers post adjuvant RT. Eight patients received EBRT prior to BT (Range: 30-50Gy). Twenty-two patients (28.9%) received salvage chemotherapy before consideration of brachytherapy. Brachytherapy application was done using MUPIT in 38, Vienna applicator in 20, Syed Neblett in 8, central vaginal cylinder in 3, multicatheter intravaginal applicator in 2, tandem-ovoids in 4 and Houdek applicator in 1 patient. Median cumulative EQD2 for all courses of radiation was 108 Gy (IQR 92-123 Gy). At median follow up of 39 months, local control (LC), progression-free survival (PFS) and Overall survival (OS) at 2-years was 60%, 56.3%, and 72.9 respectively. Patients who had recurrences beyond 2 years had significantly better OS compared to early recurrences. Patients who received BT doses >40 Gy had a higher LC and PFS. Grade 3 to 4 late rectal toxicity was seen in 10 (13%), bladder toxicity in 6 (8%) and vaginal fibrosis in 24 (31%) patients. CONCLUSION: The use of advanced BT approach in reirradiation setting is a feasible and safe option in treatment of post-treatment recurrent cervical, endometrial, and vaginal cancers.

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.