The impact of advancing the standard of care in radiotherapy on operational treatment resources

PURPOSE

To demonstrate the impact of implementing hypofractionated prescription regimens and advanced treatment techniques on institutional operational hours and radiotherapy personnel resources in a multi-institutional setting. The study may be used to describe the impact of advancing the standard of care with modern radiotherapy techniques on patient and staff resources.

METHODS

This study uses radiation therapy data extracted from the radiotherapy information system from two tertiary care, university-affiliated cancer centers from 2012 to 2021. Across all patients in the analysis, the average fraction number for curative and palliative patients was reported each year in the decade. Also, the institutional operational treatment hours are reported for both centers. A sub-analysis for curative intent breast and lung radiotherapy patients was performed to contextualize the impact of changes to imaging, motion management, and treatment technique.

RESULTS

From 2012 to 2021, Center 1 had 42 214 patient plans and Center 2 had 43 252 patient plans included in the analysis. Averaged over both centers across the decade, the average fraction number per patient decreased from 6.9 to 5.2 (25%) and 21.8 to 17.2 (21%) for palliative and curative patients, respectively. The operational treatment hours for both institutions increased from 8 h 15 min to 9 h 45 min (18%), despite a patient population increase of 45%.

CONCLUSION

The clinical implementation of hypofractionated treatment regimens has successfully reduced the radiotherapy workload and operational treatment hours required to treat patients. This analysis describes the impact of changes to the standard of care on institutional resources.

Prevalence and Prognostic Significance of PIK3CA Mutation and CNV Status and Phosphorylated AKT Expression in Patients With Cervical Cancer Treated With Primary Surgery

Currently, there are limited and conflicting reports on the prognostic utility of PIK3CA and associated pathway markers for cervical cancers treated with primary surgical management. Moreover, current studies are lacking complete characterization of adjuvant treatment with RT and/or chemotherapy. We aimed to document the prevalence, clinicopathologic, adjuvant treatment details, and prognostic value of PI3K/AKT pathway mutations and copy number variation and phosphorylated AKT status in patients with cervical cancers treated with primary surgery. A clinicopathologic review was performed on a retrospective cohort of 185 patients with cervical cancer, treated with primary surgery at a single tertiary institution. Next-generation sequencing and digital PCR was used to determine PI3K/AKT pathway mutational status and PIK3CA copy number variation, respectively, and fluorescent immunohistochemistry measured phosphorylated AKT expression. In all, 179 of 185 (96.8%) of tumors were successfully sequenced; 48 (26.8%) were positive for PI3K/AKT pathway mutations-the majority (n=37, 77.1%) PIK3CA mutations. PIK3CA mutation was associated with pathologically positive lymph nodes [12 (32%) vs. 22 (16%); P =0.022] and indication for postoperative chemoradiotherapy [17 (45.9%) vs. 32 (22.5%); P =0.004]. On multivariable analysis, PIK3CA status was not associated with overall survival ( P =0.103) or progression-free survival ( P =0.240) at 5 yrs, nor was PIK3CA copy number variation status. phosphorylated AKT ≤ median significantly predicted for progression-free survival [multivariable hazard ratio 0.39 (0.17-0.89; P =0.025)] but not overall survival ( P =0.087). The correlation of PIK3CA with pathologic positive lymph node status yet lack of association with survival outcomes may be due to the use of adjuvant postoperative therapy. PIK3CA assessment before radical hysterectomy may help identify patients with a higher risk of node-positive disease.

Is Ultrahypofractionated Whole Pelvis Radiation Therapy (WPRT) as Well Tolerated as Conventionally Fractionated WPRT in Patients With Prostate Cancer? Early Results From the HOPE Trial

OBJECTIVE

The aim of this work was to evaluate the acute toxicity and quality-of-life (QOL) impact of ultrahypofractionated whole pelvis radiation therapy (WPRT) compared with conventional WPRT fractionation after high-dose-rate prostate brachytherapy (HDR-BT).

METHODS AND MATERIALS

The HOPE trial is a phase 2, multi-institutional randomized controlled trial of men with prostate-confined disease and National Comprehensive Cancer Network unfavorable intermediate-, high-, or very-high-risk prostate cancer. Patients were randomly assigned to receive conventionally fractionated WPRT (standard arm) or ultrahypofractionated WPRT (experimental arm) in a 1:1 ratio. All patients underwent radiation therapy with 15 Gy HDR-BT boost in a single fraction followed by WPRT delivered with conventional fractionation (45 Gy in 25 daily fractions or 46 Gy in 23 fractions) or ultrahypofractionation (25 Gy in 5 fractions delivered on alternate days). Acute toxicities measured during radiation therapy and at 6 weeks posttreatment were assessed using the clinician-reported Common Terminology Criteria for Adverse Events version 5.0, and QOL was measured using the Expanded Prostate Cancer Index Composite (EPIC-50) and International Prostate Symptom Score (IPSS).

RESULTS

A total of 80 patients were enrolled and treated across 3 Canadian institutions, of whom 39 and 41 patients received external radiation therapy with conventionally fractionated and ultrahypofractionated WPRT, respectively. All patients received androgen deprivation therapy except for 2 patients treated in the ultrahypofractionated arm. The baseline clinical characteristics of the 2 arms were similar, with 51 (63.8%) patients having high or very-high-risk prostate cancer disease. Treatment was well tolerated with no significant differences in the rate of acute adverse events between arms. No grade 4 adverse events or treatment-related deaths were reported. Ultrahypofractionated WPRT had a less detrimental impact on the EPIC-50 bowel total, function, and bother domain scores compared with conventional WPRT in the acute setting. By contrast, more patients treated with ultrahypofractionated WPRT reached the minimum clinical important difference on the EPIC-50 urinary domains. No significant QOL differences between arms were noted in the sexual and hormonal domains.

CONCLUSIONS

Ultrahypofractionated WPRT after HDR-BT is a well-tolerated treatment strategy in the acute setting that has less detrimental impact on bowel QOL domains compared with conventional WPRT.

Clinical implementation of 3D transvaginal ultrasound for intraoperative guidance of needle implant in template interstitial gynecologic high-dose-rate brachytherapy

PURPOSE

To demonstrate novel clinical implementation of a 3D transvaginal ultrasound (3DTVUS) system for intraoperative needle insertion guidance in perineal template interstitial gynecologic high-dose-rate brachytherapy and assess its impact on implant quality.

METHODS AND MATERIALS

Interstitial implants began with preimplant 3DTVUS to visualize the tumor and anatomy, with intermittent 3DTVUS to assess the implant and guide needle adjustment. Analysis includes visualization of the implant relative to anatomy, identification of cases where 3DTVUS is beneficial, dosimetry, and a survey distributed to 3DTVUS clinicians.

RESULTS

Seven patients treated between November 2021 and October 2022 were included in this study. Twenty needles were inserted under 3DTVUS guidance. The tumor and vaginal wall were well-differentiated in four and all seven patients, respectively. Patients with tumours below the superior aspect of the vagina are suited for 3DTVUS. Four radiation oncologists responded to the survey. There was general agreement that 3DTVUS improves implant and anatomy visualization and is preferred over standard 2D ultrasound guidance techniques.

CONCLUSIONS

Based on qualitative feedback from primary users and a small preliminary patient cohort, 3DTVUS imaging improves tumor and vaginal wall visualization during gynecologic perineal template interstitial needle implant and is a powerful tool for implant assessment in an intraoperative setting.

Estimated absolute percentage of biopsied tissue positive for Gleason pattern 4 (eAPP4) in low dose rate prostate brachytherapy: Evaluation of prognostic utility in a large cohort

PURPOSE

To determine whether a system to estimate Absolute Percentage of Biopsied Tissue Positive for Gleason Pattern 4 (eAPP4) is useful as a prognostication tool for patients with intermediate risk prostate cancer (IR-PCa) undergoing low dose rate prostate brachytherapy.

METHODS

497 patients with IR-PCa and known grade group 2 or 3 disease treated with low dose rate seed brachytherapy (LDR-BT) at a quaternary cancer centre were retrospectively reviewed. Prostate biopsies for each patient included Gleason grading with synoptic reporting that did not include percentage of pattern 4 disease found within the sample. Each core was assigned a grade grouping, however, and that was used with optimized estimates of percentage of pattern four disease to estimate eAPP4. Outcomes including cumulative incidence of recurrence (CIR), treatment of recurrent disease (RRX), and metastasis-free survival (MFS) were then reviewed and the prognostic value of eAPP4 evaluated.

RESULTS

428 (86%) patients had Gleason grade group 2 and 69 (14%) patients had Gleason grade group 3 disease. 230 (46%) patients had National Comprehensive Cancer Network (NCCN) favourable intermediate at baseline, while 267 (54%) of patients had NCCN unfavourable intermediate at baseline. Median follow-up was 7.3 (5.5-9.6) years. eAPP4 was predictive of CIR (p = 0.003), RRX (p = 0.003), or MFS (p = 0.001) events, while Gleason grade grouping alone was not. eAPP4 was strongest as a predictor for MFS when estimates of 30% (grade group 2) and 80% (grade group 3) were used [HR 1.07 (1.03-1.12); p = 0.001].

CONCLUSIONS

eAPP4 was strongly predictive of recurrence and metastasis-free survival in a large cohort of patients receiving LDR-BT treatment for IR-PCa. Treatment of future patients with IR-PCa could include the use of eAPP4 prognostication.

Impact of Immune, Inflammatory, and Nutritional Indices on Outcome in Patients with Cervical Cancer Treated with Definitive (Chemo)radiotherapy

PURPOSE/OBJECTIVE(S)

Systemic immune, inflammatory, and nutritional indices have been shown to be prognostic for outcome across a range of tumor sites. However, a comprehensive analysis of these markers in patients with cervical cancer treated with definitive (chemo)radiotherapy [(C)RT] has not been performed. We hypothesized that systemic immune, inflammatory, and nutritional indices may be associated with progression free survival (PFS) and overall survival (OS) in patients undergoing definitive (C)RT for cervical cancer.

MATERIALS/METHODS

Patients with cervical cancer treated with definitive (C)RT from 1999 - 2015 were identified from a single cancer institution's retrospective clinicopathological database. Pre-treatment immune, inflammatory, and nutritional parameters were collected, and indices derived. Systemic immune-inflammation index (SII) = neutrophil count x platelet count / lymphocyte count(10^9/L); PLR = platelet count / lymphocyte count(10^9/L), NLR = neutrophil count / lymphocyte count (10^9/L); MLR = monocyte count / lymphocyte count (10^9/L); albumin to alkaline phosphatase ratio (AAPR) = serum albumin level (g/L)/alkaline phosphatase level (U/L) and prognostic nutritional index (PNI) = serum albumin (g/L) + 5 x lymphocyte count (10^9/L). Univariate analysis was first performed on each parameter as continuous variables for PFS and OS. For variables with statistically significant associations, ROC curves were analyzed to determine if an optimal cut point could be established for each outcome. Common cut points were then defined for each variable. PFS and OS were analyzed by the Kaplan-Meier method and the Log-Rank test. Multivariate analysis was performed using Cox regression with covariates of tumor stage, histology, and age. P-values of <0.05 were considered statistically significant.

RESULTS

A total of 196 patients were identified; median follow-up 7 years. 131 (67%) had stage I-II and 65 (33%) stage III-IV disease. 187 (95%) received CRT and 9 (5%) RT alone. Higher SII (≤700 vs >700; p = 0.01), higher PLR (≤ 250 vs >250; p<0.001) and higher NLR (≤ 5 vs >5; p = 0.003) were associated with worse PFS. Higher SII [≤700 vs >700: 5y OS 74.9 vs 55.8; p = 0.02], higher PLR [≤ 250 vs >250: 5y OS 69.9% vs 42.0%; p<0.001] and higher NLR [≤ 5 vs >5: 5y OS 65.3% vs 51.0%; p = 0.01] were associated with worse OS. MLR, AAPR and PNI were not associated with outcome on univariate analysis. On multivariate analysis, SII and PLR were independently associated with both PFS [SII: HR 1.647 (CI 1.029-2.639), p = 0.038; PLR: HR 2.301 (95% CI 1.507 - 3.512), p = <0.001], and OS [SII: HR 1.649 (95% CI 1.009-2.696), p = 0.046; PLR: HR 2.212 (95% CI 1.416-3.455), p<0.001]; NLR did not remain statistically significant.

CONCLUSION

SII and PLR, but not nutritional indices, were independently associated with PFS and OS in patients with cervical cancer treated with definitive (C)RT. Further evaluation of these systemic immune and inflammatory indices in a validation set will be required to better define their clinical utility.

Erectile Dysfunction Pharmacotherapy Utilization after 60Gy in 20 Fractions Volumetric Modulated Arc Therapy to the Prostate

PURPOSE/OBJECTIVE(S)

To determine which factors predict for worsening erectile function after highly conformal, modestly hypofractionated radiotherapy to the prostate.

MATERIALS/METHODS

All patients who received 60Gy in 20 fractions, volumetric modulated arc therapy to the prostate across 4 centers over 9 years were included in this study. The provincial electronic medical record was interrogated to identify any new prescriptions for erectile dysfunction (ED) medication, any change in prescription of ED medication or any permanent discontinuance of ED medication persisting beyond 6 months post completion of any androgen deprivation therapy. The penile bulb, penile crux and penile shaft structures were retrospectively contoured. A Youden receiver-operator-curve analysis, logistic regression, and neural network based interpretable machine learning analysis were then used to determine dependencies between worsening ED and clinical factors including mean doses to these structures.

RESULTS

Two-hundred-twelve patients with median (inter-quartile-range) follow-up of 3.6 (3.2-4.4) years were identified. Median age was 72 (67-76) years. 104 (49%) patients received androgen deprivation therapy. Prior to treatment, 52 (25%) patients were on ED medication: 20 (9%) on sildenafil, 28 (13%) on tadalafil and 4 (8%) on vardenafil. Median PTV volume was 158.9 (129.8-192.1) cc. Median penile bulb, penile crux and penile shaft volumes were 4.7 (3.6-6.2) cc, 6.5 (5.1-8.5) cc and 93.3 (80.6-106.2) cc, respectively. PTV V95 was 99.8 (99.5-99.9)%. Mean doses to penile bulb, penile crux and penile shaft were 2094.8 (1306.2-3036.3) cGy, 2094.8 (1306.2-3036.3) cGy and 444.4 (313.2-650.5), respectively. Fifty-nine (28%) patients had a worsening of ED after treatment: 25 (12%) started a new ED medication, 6 (3%) had a prescription change and 28 (13%) stopped ED medication. On univariate analyses pretreatment use of ED medication predicted for worsening ED: odds ratio (OR) yes vs no: 10.2 (5.0 - 20.8; p<0.001). A trend towards mean dose to penile bulb [OR ≤2343.9 vs >2343.9: 1.7 (0.9-3.2; p = 0.08)] predicting for worsening ED was observed. Mean doses to penile crux [OR <1725.8 vs > 1725.8: 2.6 (1.3-5.2; p = 0.005)] and penile shaft [OR ≤344.9 vs >344.9: 5.2 (2.2-12.2; p<0.001)] predicted for worsening ED. Use of androgen deprivation therapy, and age at time of radiotherapy were not predictive of worsening ED. On multivariate analysis, only mean dose to penile shaft [OR ≤344.9 vs >344.9: 6.3 (1.9-20.3; p = 0.002)] and pretreatment use of ED medication [OR yes vs no: 11.1 (5.3-23.2; p<0.001)] predicted for worsening ED. A neural network analysis suggested that penile shaft mean dose and pre-treatment ED medication use are the most important factors in predicting worsening ED.

CONCLUSION

In this limited analysis, pre-treatment use of ED medication and mean dose to penile shaft predicted for worsening ED after treatment with modestly hypofractionated radiotherapy for prostate cancer.

Assessment of dose to vaginal mucosa for gynecologic template interstitial high-dose-rate brachytherapy using Monte Carlo simulation

Purpose

This study investigated reliable vaginal mucosa dose-volume histogram (DVH) metrics in gynecologic template interstitial high-dose-rate brachytherapy (HDR-BT) for the purpose of standardized dose reporting.

Material and methods

Gynecologic template (Syed/Neblett) interstitial HDR-BT patients treated from September 2016 to November 2022 at the study institute were included in the cohort. Each patient implant included a vaginal mucosa contour defined by a 5 mm expansion from vaginal cylinder, then another volume with clinical target volume subtracted. DVH metrics were investigated between D0.1cc to D4cc. Clinical plans were re-calculated using Monte Carlo (MC) simulations both in heterogeneous material and in water.

Results

The patient cohort included 61 patients with clinical plans using conventional homogeneous dose calculation (TG43). Heterogeneous vs. water MC dose differences were between -1.1% and -1.4% for all metrics investigated. DVH metrics D1cc and smaller resulted in > 5% discrepancies between TG43 and MC dose (to water) calculation due to the proximity of source positions in/nearby the vaginal mucosa. Reliability improved when DVH metric volume was larger (D2cc and D4cc). Both D2cc and D4cc presented very high linear correlation between TG43 and MC reported doses for the vagina, and average ± standard deviation dose difference was 4.6 ±2.9% and -3.0 ±1.9%, respectively. Dose differences decreased when the clinical target volume was removed: -1.5 ±3.5% and -0.8 ±2.1% for D2cc and D4cc, respectively.

Conclusions

For perineal template gynecologic HDR-BT procedures, the 2 cc volume is the smallest representative volume that reliably reports vaginal dose and at minimum should be reported to establish dose and outcome evaluation.

Hypomagnesemia and Survival in Patients with Cervical Cancer Treated with Definitive Chemoradiotherapy

PURPOSE/OBJECTIVE(S)

Hypomagnesemia is a common side effect of platinum-based chemotherapy regimens. Although there are data reporting that hypomagnesemia is associated with worse survival in patients receiving platinum-based chemotherapy or chemoradiotherapy (CRT), this has not been documented in patients with cervical cancer treated with definitive CRT. We hypothesized that in patients with cervical cancer undergoing definitive CRT, on-treatment hypomagnesemia would be associated with longer treatment duration and worse cancer-specific survival (CSS).

MATERIALS/METHODS

Patients with cervical cancer treated with definitive CRT from 1999 to 2015 were identified from a single cancer center's clinicopathologic database. Lowest on-treatment magnesium value was recorded and categorized as per Common Terminology Criteria for Adverse Events (CTCAE) v5.0 grading (grade 1: <0.7 - 0.5 mmol/L, grade 2: <0.5 - 0.4 mmol/L, grade 3: <0.4-0.3 mmol/L, and grade 4 <0.3 mmol/L). Grade 0 was defined as ≥ 0.7 mmol/L. Treatment duration was defined as the number of days between the first day of radiotherapy until the last day of pelvic treatment (either brachytherapy or pelvic external beam radiotherapy boost). Prolonged treatment was considered as any treatment duration greater than 63 days. CSS for patients with either grade 0-1 or grade ≥ 2 CTCAE v5.0 magnesium toxicity was estimated using the Kaplan-Meier method, and the Peto & Peto modification to the generalized Gehan-Wilcoxon was used to determine statistical significance between groups. Associations with prolonged treatment duration was explored using logistic regression. P-values of <0.05 were considered statistically significant.

RESULTS

A total of 186 patients were identified; median follow-up was 7 (IQR 2-11) years. 125 (67%) had stage I-II disease and 61 (33%) stage III-IV. Median treatment duration was 51 (IQR 48-57) days. All patients received concurrent weekly cisplatin-based chemotherapy with RT: the majority (n = 133; 72%) received 5 or 6 cycles. 147 (79%) patients received routine IV magnesium infusion with their chemotherapy and 173 (93%) received routine IV mannitol. During treatment the highest CTCAE v5.0 magnesium toxicity score was grade 0-1 in 158 (85%) and grade ≥ 2 in 28 (15%). Magnesium grade ≥ 2 was associated with worse 5-year CSS [grade 0-1: 5yr CSS 67.2%, (95% CI 60.1-75.1); grade ≥ 2: 5yr CSS 50%, (95% CI 34.5-72.4); p = 0.039]. Magnesium status was not associated with an increase in treatment duration [OR 1.465 (95% CI 0.3177 - 6.753); p = 0.625].

CONCLUSION

On-treatment hypomagnesemia ≥ grade 2 (CTCAE v5.0) was associated with worse CSS but did not predict longer treatment duration. This is the first study that shows a detrimental survival impact of on-treatment hypomagnesemia in this patient population. These findings highlight the need to ensure adequate monitoring, support and correction of magnesium during definitive CRT.

Prospective Application of an Artificial Intelligence Decision Support Tool for Applicator and Needle Selection in High-Dose-Rate Brachytherapy for Cervical Cancer Patients

PURPOSE/OBJECTIVE(S)

To assess the performance of an artificial intelligence (AI)-based decision support tool under differing thresholds to determine optimal applicator selection in a prospective clinical setting.

MATERIALS/METHODS

Cervical cancer patients scheduled for high-dose-rate brachytherapy implants with intracavitary tandem and ring (IC) or interstitial tandem and ring (IC/IS) implants in a single tertiary cancer center were eligible for enrollment. Prior to the first brachytherapy implant, a diagnostic MRI was acquired. The clinical target volume and the expected inserted position of the intrauterine tandem and ring were identified and contoured on the T2-MRI. An in-house artificial intelligence-based predicted the need for an IC or IC/IS implant, based on target volume geometric features. For IC/IS implants, an optimal needle arrangement for target coverage was also predicted. Blinded to the AI outcome, a clinical determination was made by the clinician reviewing the MR image. AI algorithm prediction provided a confidence level associated with each decision. The algorithm performance for different confidence thresholds using the IC applicator of 50%, 60%, and 80% was investigated. Performance metrics of the initial clinical determination and the AI prediction were calculated based on the consensus optimal applicator determined from an assessment of planning dosimetry in the first fraction and clinical use for the final brachytherapy implants and fractions. The performance metrics were accuracy, precision, and recall.

RESULTS

A total of 10 eligible patients were accrued between December 2020 and October 2022. Table 1 shows the initial clinical determination and consensus applicator AI predictions that were made with different confidence thresholds. The optimal confidence threshold (60%) yielded performance scores of 80%, 83.3%, and 83.3% for the accuracy, precision, and recall, respectively. The performance metrics were equivalent for the optimal confidence threshold and the initial clinical decision.

CONCLUSION

The AI-based decision support tool shows strong predictive results for a clinical brachytherapy application that is important to patient outcome. This prospective study demonstrates that the algorithm's utility is a critical step in using AI-based tools clinically. Further work to determine the optimal brachytherapy applicator, based on treatment planning dosimetry, is required.

Local Prostate Radiation Therapy and Symptomatic Local Events in De Novo Metastatic Prostate Cancer

PURPOSE

Local prostate radiation therapy (LPRT) for low-burden metastatic prostate cancer (mPCa) improves overall survival and is the standard of care. The role of LPRT in reducing symptomatic local events (SLE) remains unclear. We aimed to identify SLE risk factors and to evaluate the association between LPRT and SLE in mPCa.

METHODS AND MATERIALS

We conducted a retrospective, population-based cohort study of patients initially diagnosed with mPCa between 2005 and 2016 in a cancer registry. Patient, tumor, and treatment characteristics were obtained from chart review and the cancer registry. The coprimary endpoints were genitourinary (GU) and gastrointestinal (GI) SLE, identified by physician billing claims between 2004 and 2017 for diagnostic or therapeutic procedures potentially related to GU and GI SLE. The effect of LPRT on SLE was evaluated using both recurrent event (Andersen-Gill model) and time-to-first-event sequential landmark analyses. Risk factors for SLE were assessed by multivariable Cox regression. LPRT was defined as ≥40 Gy within 1 year of diagnosis. Metastatic burden was defined per the STAMPEDE trial.

RESULTS

Of 1363 patients, 46 (3.4%) received LPRT. Median follow-up was 27.3 and 28.9 months in the control and LPRT groups, respectively. LPRT was associated with less recurrent GU SLE (hazard ratio [HR], 0.34; 95% confidence interval [CI], 0.17-0.67; P = .002), upper tract obstruction (HR, 0.20; 95% CI, 0.05-0.84; P = .03), and cystoscopy (HR, 0.38; 95% CI, 0.15-0.96; P = .04). Metastatic burden was not associated with SLE.

CONCLUSIONS

LPRT in mPCa was associated with less recurrent GU SLE, specifically for upper tract obstruction and cystoscopy.

Indications for additional volume studies for gland volume estimation in prostate cancer brachytherapy

An estimated gland volume of > 60 cc is a relative contraindication to brachytherapy for prostate cancer. As volume estimation using biopsy ultrasound (Bx-US) alone may be inaccurate, many centers perform additional volume assessments prior to the brachytherapy procedure. At the study institution, computed tomography (CT) based volume assessments were routinely performed on all patients to determine brachytherapy eligibility. This study aimed to determine whether this CT imaging could be omitted for certain Bx-US based gland volume estimates. To investigate this, 1576 consecutive patients that received ultrasound based intraoperatively planned brachytherapy at a single comprehensive cancer center between 2003 and 2021 were reviewed. Gland volume as estimated by Bx-US, CT and magnetic resonance (MR) imaging were compared to intraoperatively contoured gland volume (ICGV) or the larger contoured gland volume on CT for any patients receiving neo-adjuvant androgen deprivation therapy (ADT) for gland downsizing (IM-US-corr). There was a significant difference between IM-US-corr and estimated gland volume for Bx-US (P < 0.001) and MR (P < 0.001), but not CT (P = 0.160). Bx-US and MR tended to underrepresent the IM-US-corr, with a > 20% difference from actual volume in 31% and 59% of cases, respectively. When Bx-US volume was estimated to be < 40 cc, < 50 cc and < 60 cc, an IM-US-corr > 60 cc was encountered in 2%, 5% and 7% of cases, respectively. In contrast, IM-US-corr > 60 cc was encountered in 0.2%, 1% and 2% of cases for CT estimates of < 40 cc, < 50 cc and < 60 cc. In patients with an estimated gland volume of < 50 cc by Bx-US, dedicated pre-operative volume studies are unlikely to alter management. However, patients above this cut-off stand to benefit from the use of additional volume assessment to better delineate gland volume and determine eligibility for brachytherapy.

Opioid consumption and pain in patients with gynecological cancer who underwent spinal anesthesia vs. general anesthesia for interstitial brachytherapy

AIMS

Interstitial brachytherapy (ISBT) is an effective option for delivering conformal high dose radiation to the target volume with better organ-at risk sparing but is thought to be more invasive and painful than other methods. This study investigated pain levels and opioid consumption in patients who received spinal anesthesia (SA) or general anesthesia (GA) for their ISBT.

MATERIALS AND METHODS

Patients that underwent ISBT from April 2014 to September 2018 were analyzed from a prospective institutional database. The most prevalent malignancies were cervical (45%), recurrent endometrial (27%) and vaginal (20%) cancers. Baseline patient characteristics, radiation treatment details, anesthesia records, and inpatient charts were obtained. Opioid consumption was quantified as oral morphine equivalent per day (OMEq/day) from implantation until removal. Pain score levels were collected by using an 11-point scoring system.

RESULTS

Ninety nine patients received GA and 40 patients received SA as their anesthesia for ISBT. During their first admission, 76 patients (55%) required intravenous opioids. Patients receiving SA had significantly lower mean pain scores on the morning of their procedure 6 (Interquartile range [IQR] 2-8) vs. 0 (IQR: 0-1); p < 0.001]. Pain did not significantly differ between cohorts at any other time. During the first admission, SA patients had a lower median opioid usage of 23 (IQR: 9-47) mg/day compared to GA patients at 38 (IQR: 21-71) mg/day (p = 0.011). No difference in opioid consumption was seen during subsequent admissions.

CONCLUSIONS

In patients undergoing ISBT, SA provides better immediate pain control post insertion compared to GA. Patients who received SA used lower amounts of opioids during their first ISBT insertion.

Success of targeted transperineal biopsy in patients on surveillance for grade group 1 prostate cancer

Introduction: We aimed to determine the minimum cross-sectional ellipsoid area on magnetic resonance (MR) of intraprostatic nodules that best predicts for subsequent targeted biopsies revealing ≥ grade group (GG) 2 disease. Methods: Forty-six patients previously diagnosed with GG 1 prostate adenocarcinoma who received cognitively fused, MR-guided, transperineal targeted biopsies in addition to six random biopsies were included in this analysis. A Youden cutpoint analysis was used to determine the ellipsoid area in the axial plane best predicting for ≥GG 2 disease within the targeted biopsy cores and logistic regression used to assess the result. Results: Median time from MR imaging to targeted biopsy was 2.4 (1.4–5.5) months. Forty of 46 (87%) patients had one nodule and 6/46 (13%) had two separate nodules on MR that received targeted biopsy. Of the 52 nodules, five (10%), 33 (63%), and 14 (27%) were Prostate Imaging–Reporting and Data System (PI-RADS) 3, 4, and 5. Thirteen (25%), six (12%), and 33 (64%) were in the anterior, medial, and posterior regions of the prostate. Median area was 0.72 (0.49–1.29) cm2 (average diameter 9.5 mm). Fifteen of 46 (33%) patients had ≥1 random biopsy and 20/52 (38%) nodules had ≥1 targeted biopsy revealing ≥GG 2 disease. The optimal area cutpoint was ≥0.7cm2, with an area under the curve of 0.671 (0.510–0.832). On logistic regression, areas ≥0.7 cm2 was solely predictive of targeted biopsy revealing ≥GG 2 disease (odds ratio 6.5, 1.3–32.4, p=0.022). Conclusions: Nodule area ≥0.7 cm2 may predict for transperineal-based targeted biopsies being positive for ≥GG 2 disease when 1–2 cores are taken.

Changing Landscape of Radiation Therapy for Advanced Cervical Cancer With a Focus on Interstitial Brachytherapy: A Canadian Practice Patterns Survey

PURPOSE

To document the evolution of radical radiation therapy and interstitial brachytherapy (ISBT) utilization practice patterns across Canada, including use of imaging, technical details, and usage of anesthesia/analgesia, and to compare advanced (AC) versus nonadvanced (nAC) brachytherapy (BT) center practices.

METHODS AND MATERIALS

All Canadian centers with BT services were identified. One gynecology radiation oncologist per center was sent a 64-item questionnaire regarding the center's practice for patients with cervical cancer. Centers were categorized based on availability of advanced BT expertise (AC) versus those referring patients to other centers for advanced BT techniques (nAC). Aggregate responses are reported and compared with practice patterns identified in our previous survey. Descriptive statistics were used to summarize data, and the Fisher exact test, Fisher-Freeman-Halton, or Mann-Whitney-Wilcox test was used for comparisons.

RESULTS

Thirty-seven of 38 respondents completed the survey (response rate: 97.4%). Compared with 2015, there has been an increase in utilization of magnetic resonance imaging as the sole imaging modality for BT planning: 3 of 26 (11%) versus 12 of 37 (32%; P = .03). The number of centers with the ability to perform ISBT increased in 2020 compared with 2015 (26/37 [70%] vs 13/26 [50%], P = .710); this trend is likely due to an increase in use of hybrid (Vienna, Utrecht, Venezia) applicators (36% [2015] vs 84% [2020]; P = .175). Fifteen (40%) centers had the ability to perform perineal-ISBT (P-ISBT). Sixteen and 21 centers were identified as AC and nAC, respectively. All 16 AC centers had the ability to perform ISBT, compared with only 10 nAC centers (P < .001). A higher proportion of AC centers had fellowship-trained radiation oncologists performing brachytherapy, compared with nAC centers (94% vs 14%, P < .001). In terms of anesthesia, conscious sedation was the only available choice at low-patient-volume centers (8/37, 21%) performing intracavitary BT only. Those performing ISBT had choice of general, spinal, and epidural anesthesia.

CONCLUSIONS

In Canada, high-quality, modern management radiation therapy practices are consistently offered to patients with cervical cancer. There is a trend toward increased utilization of ISBT. Accumulation of evidence toward the use of ISBT, increased utilization of high-quality imaging modalities such as magnetic resonance imaging, and availability of hybrid applicators are potential contributors for this upward trend.

Clinical Outcomes from Dose-Reduced Radiotherapy to the Prostate in Elderly Patients with Localized Prostate Cancer

Radical treatment of localized prostate cancer in elderly patients may lead to unacceptable treatment-associated toxicities that adversely impact quality of life without improving survival outcomes. This study reports on a cohort of 54 elderly (>70 years) patients that received 4000–5000 cGy of palliative external beam radiotherapy (EBRT) as an alternative to androgen deprivation therapy (ADT). The primary outcome of interest was the period of ADT-free survival, and secondary outcomes included overall survival (OS) and metastases-free survival (MFS). Kaplan–Meier regression was used to estimate survival outcomes. Thirty-six (67%) patients achieved a break in ADT post-radiotherapy, with a median time to ADT reinitiation of 20 months. Common Terminology Criteria for Adverse Events (CTCAE) were limited to low-grade gastrointestinal (GI) or genitourinary (GU) toxicities, with no skin toxicities observed. Grade 1 GI toxicity was observed in 9 (17%) patients, and grades 1 and 2 GU toxicities were observed in 13 (24%) and 3 (6%) patients, respectively, with no higher-grade toxicities reported. Five-year MFS and OS were 56% and 78%, respectively. In summary, the treatment regimen was well-tolerated and achieved durable ADT-free survival in most patients. Dose-reduced EBRT appears to be a viable alternative to ADT in elderly patients with localized prostate cancer.

Increasing Demand on Human Capital and Resource Utilization in Radiation Therapy: The Past Decade

PURPOSE

To quantify the change resource utilization in radiation therapy in the context of advancing technologies and techniques over the last decade.

METHODS AND MATERIALS

Prospectively, the time to complete radiation therapy workflow tasks was captured between January 1, 2020, and December 31, 2020. The institutional task workflows are specific to each technique and broadly organized into 4 categories: 3-dimenstional conformal radiation therapy, intensity modulated radiation therapy, volumetric modulated arc therapy simple, and volumetric modulated arc therapy complex. These discipline-specific task times were used to quantify a resource utilization factor, which is the median time taken to complete all tasks for each category divided by the median time for 3-dimensional conformal radiation therapy treatments. Retrospectively, all plans treated between January 1, 2012, and December 31, 2019, were quantified and categorized. The resource factor was applied to determine resource utilization. For context, institutional staffing levels were captured across the same decade for medical dosimetrists, medical physicists, and radiation oncologists.

RESULTS

This analysis includes 30,229 patient plans in the retrospective data set and 4747 patient plans in the prospective data set. This analysis demonstrates that over this period, patient numbers increased by approximately 45%, whereas time-based human resources increased by almost 150%. The resource allocation factors for 3-dimenstional conformal radiation therapy, intensity modulated radiation therapy, volumetric modulated arc therapy simple, and volumetric arc therapy complex were 1.0, 2.4, 2.9, and 4.3, respectively. Across the 3 disciplines, staffing levels increased from 15 to 17 (13%) for medical dosimetrists, from 10 to 13 (30%) for medical physicists, and from 16 to 23 (44%) for radiation oncologists.

CONCLUSIONS

This work demonstrates the increase in resource utilization due to the introduction of advanced technologies and changes in radiation therapy techniques over the past decade. Human resource utilization is the predominant factor and should be considered with increasing patient volume for operational planning.

MRI-TRUS registration methodology for TRUS-guided HDR prostate brachytherapy

Purpose

High‐dose‐rate (HDR) prostate brachytherapy is an established technique for whole‐gland treatment. For transrectal ultrasound (TRUS)‐guided HDR prostate brachytherapy, image fusion with a magnetic resonance image (MRI) can be performed to make use of its soft‐tissue contrast. The MIM treatment planning system has recently introduced image registration specifically for HDR prostate brachytherapy and has incorporated a Predictive Fusion workflow, which allows clinicians to attempt to compensate for differences in patient positioning between imaging modalities. In this study, we investigate the accuracy of the MIM algorithms for MRI‐TRUS fusion, including the Predictive Fusion workflow.

Materials and Methods

A radiation oncologist contoured the prostate gland on both TRUS and MRI. Four registration methodologies to fuse the MRI and the TRUS images were considered: rigid registration (RR), contour‐based (CB) deformable registration, Predictive Fusion followed by RR (pfRR), and Predictive Fusion followed by CB deformable registration (pfCB). Registrations were compared using the mean distance to agreement and the Dice similarity coefficient for the prostate as contoured on TRUS and the registered MRI prostate contour.

Results

Twenty patients treated with HDR prostate brachytherapy at our center were included in this retrospective evaluation. For the cohort, mean distance to agreement was 2.1 ± 0.8 mm, 0.60 ± 0.08 mm, 2.0 ± 0.5 mm, and 0.59 ± 0.06 mm for RR, CB, pfRR, and pfCB, respectively. Dice similarity coefficients were 0.80 ± 0.05, 0.93 ± 0.02, 0.81 ± 0.03, and 0.93 ± 0.01 for RR, CB, pfRR, and pfCB, respectively. The inclusion of the Predictive Fusion workflow did not significantly improve the quality of the registration.

Conclusions

The CB deformable registration algorithm in the MIM treatment planning system yielded the best geometric registration indices. MIM offers a commercial platform allowing for easier access and integration into clinical departments with the potential to play an integral role in future focal therapy applications for prostate cancer.

Excessive waitlists and delays to treatment with low-dose-rate brachytherapy predict an increased risk of recurrence and metastases in intermediate-risk prostatic carcinoma

•

Resource constraints have led to prolonged wait-times for prostate brachytherapy.

•

Increased wait times predict a significant increase in recurrence and metastases.

•

Better resource planning is needed to reduce management delays & improve outcomes.

Purpose

It has previously been shown that increased wait times for prostatectomy are associated with poorer outcomes in intermediate-risk prostatic carcinoma (PCa). However, the impact of wait times on PCa outcomes following low-dose-rate brachytherapy (LDR-BT) are unknown.

Methods and Materials

We retrospectively reviewed 466 intermediate-risk PCa patients that underwent LDR-BT at a single comprehensive cancer center between 2003 and 2016. Wait times were defined as the time from biopsy to LDR-BT. The association of wait times with outcomes was evaluated using Cox and Fine-Gray regression in both univariate and multivariate models.

Results

Median (interquartile range) follow-up and wait time for all patients were 8.1 (6.3–10.4) years and 5.1 (3.9–6.9) months, respectively. Among NCCN unfavourable intermediate-risk (UIR) patients (n = 170; 36%), increased wait times predicted both a greater cumulative incidence of recurrence [MHR = 1.01/month of wait time (95% CI: 1.00–1.03); P = 0.044] and metastases [MHR = 1.04/month of wait time (95% CI: 1.02–1.06); P < 0.001] in multivariate modeling. In NCCN favourable intermediate-risk (FIR) patients, there was no significant association between wait time and recurrence or metastases risk. Among all intermediate-risk patients, wait time was associated with an increase in the incidence of metastases [MHR = 1.03/month of wait time (95% CI: 1.02–1.05); P < 0.001], but not recurrence in multivariate models. There was no association between wait time and overall survival in the UIR, FIR, or all intermediate-risk cohorts.

Conclusions

Resource constraints within this center’s public healthcare system have contributed to waitlists exceeding 5-months in length. This study finds that patients with UIR PCa experience a 1% increase in the risk of recurrence and 4% increase in the risk of metastases with each additional month of delay in definitive disease management. Preventing such extended management delays in LDR-BT may improve disease-related outcomes in patients with PCa.

Relationship of Urethral Dose and Genitourinary Toxicity Among Patients Receiving Vaginal High Dose Rate Interstitial Brachytherapy

AIMS

Interstitial brachytherapy (ISBT) plays an important role in the management of locally advanced gynaecological malignancies. However, the relationship between urinary toxicity and dose to the urethra is not well understood. We sought to evaluate the correlation between urethral dose and the incidence of genitourinary complications among patients undergoing vaginal high dose rate ISBT.

MATERIALS AND METHODS

Eighty-three patients treated with ISBT between August 2014 and April 2018 were retrospectively reviewed. CTCAE version 5.0 was used to grade toxicity. Individual treatment plans were evaluated to collect dose parameters. Urethral contours were added to the structure sets using a uniform 1 cm diameter brush and minimum doses to the hottest 0.1, 0.2 and 0.5 cm³ (D0.1cm³, D0.2cm³ and D0.5cm³) of the urethra were obtained. Total (ISBT ± external beam radiotherapy) equivalent doses in 2 Gy fractions (EQD2) received by the targets and organs at risk were calculated. Numerical counts (%) and medians (interquartile range) were used to characterise the data. Fisher's exact and the Mann-Whitney-Wilcox tests were used as appropriate. Receiver operator curve analysis was used to define the urethral threshold dose that correlated to genitourinary toxicity.

RESULTS

The median age and follow-up times were 67 years (59-75) and 25 months (16-37), respectively. Patients had predominantly primary endometrial (49%) and vaginal (37%) cancer, with four (5%) patients with metastatic rectal cancer to the vagina. Twenty-four of 79 (30%) patients experienced acute genitourinary toxicity and 34 of 71 (48%) experienced late genitourinary toxicity. In both analyses, the median urethral dose was significantly higher among those with toxicity. Receiver operator curve analysis indicated that D0.1cm³, D0.2cm³ and D0.5cm³ of the urethra were associated with the development of toxicity at doses >78, >71 and >62 Gy, respectively.

CONCLUSION

Urethral dose seems to predict genitourinary toxicity in ISBT of vaginal tumours. Further study with an expanded cohort and longer follow-up is warranted.

Unactivated leukocyte expression of C-reactive protein is minimal and not dependent on rs1205 genotype

C-reactive protein (CRP), a prominent component of the innate immune system, is implicated in the pathophysiology of many conditions. CRP production primarily occurs in the liver; but contributions from other tissues is unclear. The Genotype-Tissue Expression Portal shows essentially no expression in whole blood and reports in the literature are conflicting. Multiple genomic variants influence serum levels of CRP. We measured CRP mRNA expression in leukocytes and sought to determine if rs1205 genotype influences leukocyte expression. Leukocytes were obtained from 20 women differing by genotype. Quantitative, real-time PCR (RT-qPCR) detected CRP and reference gene (GAPDH) mRNA. Leukocyte expression was calculated by the 2^ΔCT method, and against a standard curve. Digital drop PCR was also used to calculate expression ratios. Student's t test and linear regression methods examined possible differences between genotypes. During 32 runs (10 replicates each), the RT-qPCR mean (SD) CRP/GAPDH ratio was 3.39 × 10^–4 (SD 1.73 × 10^–4) and 3.15 × 10^–4 (SD 1.64 × 10^–4) for TT and CC genotypes respectively, p = 0.76; and digital drop PCR results were similar. Serum CRP was not significantly different between genotypes, nor correlated with leukocyte expression. CRP is minimally expressed in unactivated leukocytes and this expression is not likely influenced by rs1205 genotype.

Local prostate radiotherapy in metastatic prostate cancer and symptomatic local events

111

Background: Local prostate radiotherapy (LPRT) is associated with improved overall survival in patients with low metastatic burden (MB) and is now standard of care. However, the role of LPRT in reducing symptomatic local events (SLE) in metastatic prostate cancer (MPC) remains unclear and requires long-term follow-up. The purpose of this study was two-fold: i) identify the risk factors associated with SLE, and ii) evaluate the association between LPRT and SLE in MPC. Methods: We conducted a retrospective, population-based cohort study of patients diagnosed with initial MPC between 2005 and 2016. Patients were identified through the Alberta Cancer Registry and patient, tumour, and treatment characteristics were collected by chart review. Data were linked to physician billing claims between 2004 and 2017 for diagnostic or therapeutic procedures potentially related to genitourinary (GU) and gastrointestinal (GI) SLE including percutaneous nephrostomy (PCN) and ureteric stent insertion (USI), cystoscopy, TURP, TURBT, colonoscopy and proctosigmoidoscopy. Both Andersen-Gill recurrent event and multivariable Cox regression time to first event analyses were conducted to evaluate the effect of LPRT on the occurrence of these procedures. Patients who underwent radical prostatectomy were excluded. LPRT was defined as 40 Gy or higher total dose to the prostate within one year of diagnosis. Patients with a SLE occurring after diagnosis but prior to LPRT were allocated to the control group. MB was defined as per STAMPEDE. Covariates for both models included MB, age at diagnosis, PSA at diagnosis, clinical T- and N-stage, and Gleason score (GS). Results: Of a total cohort of 1363 patients, 745 (54.7%) had high MB and 450 (33%) had low MB. Fifty-four (4%) received LPRT, of which 14.8% had high MB. Of those receiving LPRT, median PSA was 9.4, 79.6% had GS of 8-10, and 59.3% had T3-T4 disease. One or more SLE were observed in 43.5% and 37% of the control and LPRT groups, respectively. Among those with SLE, the median SLE frequency was 2 (interquartile range [IQR], 2-5) and 1 (IQR, 1-2.3) for the control and LPRT groups, respectively. On recurrent event analysis, LPRT was associated with lower risk of composite GU SLE (HR 0.34, 95% CI 0.17-0.67; p = 0.002), PCN and USI (HR 0.20, 95% CI 0.05-0.84; p = 0.027) and cystoscopy (HR 0.38, 95% CI 0.15-0.96; p = 0.041). Risk factors for GU SLE were T4 disease, GS of 8-10 and unknown GS. Risk factors for PCN and USI were T3, TX and N1 disease, GS of 8-10 and unknown GS. On time to first event analysis, there were no statistically significant differences for all outcomes between the control and LPRT groups. MB was not a risk factor for SLE in both analyses. Conclusions: LPRT was associated with lower risk for recurrent GU SLE, PCN and USI, and cystoscopy. The associated benefit in SLE reduction with LPRT warrants further study to determine if this effect is modified by MB and whether there may be a role for LPRT in patients with high MB.

Complications and side effects of high-dose-rate prostate brachytherapy

PURPOSE

To describe technical challenges and complications encountered during and after high-dose-rate prostate brachytherapy (HDR-BT) and review management of these complications.

METHODS AND MATERIALS

The authors performed a systematic review of the literature on toxicities encountered after prostate HDR-BT +/- external beam radiotherapy. A total of 397 studies were identified, of which 64 were included. A focused review of literature regarding the management of acute and late toxicities also performed.

RESULTS

Most acute toxicities include grade 0-2 genitourinary and gastrointestinal toxicity. Overall, Grade 3+ Common Terminology Criteria for Adverse Events toxicity after HDR-BT was low [genitourinary: 0-1%; gastrointestinal 0-3%]. Rates of fistula formation were <1%, and radiation cystitis/proctitis were <14% and more commonly reported in cohorts treated with HDR-BT boost and external beam radiotherapy.

CONCLUSIONS

HDR-BT both as monotherapy or combined with external beam radiotherapy for prostate cancer is well tolerated. Serious complications are rare.

Social Jetlag and Prostate Cancer Incidence in Alberta's Tomorrow Project: A Prospective Cohort Study

Simple Summary

Due to social obligations (e.g., school, work), people shift their sleep and activity time regardless of their sleep-wake preference. To compensate for the lack of sleep accumulated over the workdays, people tend to oversleep on a work-free day. This difference in sleep timing between workdays and free days resembles traveling across different time zones, which causes jetlag (a mild form of circadian disruption). Thus, it is named social jetlag. Social jetlag has been linked with obesity, metabolic disorders, and cardiovascular risk in previous research. This study assessed social jetlag in 7455 cancer-free men in Alberta’s Tomorrow Project and followed them for on average 9.6 years, 250 men were diagnosed with prostate cancer. The study found that the more social jetlag men experienced, the greater their prostate cancer risk was. This finding warrants future research to better understand the complex behavioral and biological pathways between social jetlag and prostate cancer risk.

Abstract

We investigated the association of social jetlag (misalignment between the internal clock and socially required timing of activities) and prostate cancer incidence in a prospective cohort in Alberta, Canada. Data were collected from 7455 cancer-free men aged 35–69 years enrolled in Alberta’s Tomorrow Project (ATP) from 2001–2007. In the 2008 survey, participants reported usual bed- and wake-times on weekdays and weekend days. Social jetlag was defined as the absolute difference in waking time between weekday and weekend days, and was categorized into three groups: 0–<1 h (from 0 to anything smaller than 1), 1–<2 h (from 1 to anything smaller than 2), and 2+ h. ATP facilitated data linkage with the Alberta Cancer Registry in June 2018 to determine incident prostate cancer cases (n = 250). Hazard ratios (HR) were estimated using Cox proportional hazards regressions, adjusting for a range of covariates. Median follow-up was 9.57 years, yielding 68,499 person-years. Baseline presence of social jetlag of 1–<2 h (HR = 1.52, 95% CI: 1.10 to 2.01), and 2+ hours (HR = 1.69, 95% CI: 1.15 to 2.46) were associated with increased prostate cancer risk vs. those reporting no social jetlag (p for trend = 0.004). These associations remained after adjusting for sleep duration (p for trend = 0.006). With respect to chronotype, the association between social jetlag and prostate cancer risk remained significant in men with early chronotypes (p for trend = 0.003) but attenuated to null in men with intermediate (p for trend = 0.150) or late chronotype (p for trend = 0.381). Our findings suggest that greater than one hour of habitual social jetlag is associated with an increased risk of prostate cancer. Longitudinal studies with repeated measures of social jetlag and large samples with sufficient advanced prostate cancer cases are needed to confirm these findings.

Implementation of high-dose-rate brachytherapy for prostatic carcinoma in an unshielded operating room facility

PURPOSE

The purpose of the study was to describe our approach towards safe delivery of single-fraction high-dose-rate (HDR) brachytherapy (BT) boost in patients with prostate cancer in the setting of an unshielded operating room (OR).

METHODS AND MATERIALS

A total of 95 patients received 15 Gy HDR BT boost. The procedure involved transrectal ultrasound-based catheter insertion and planning in the OR, after which the patient was moved to a shielded treatment room for radiation. This required three vital components: (1) an OR table capable of transporting the patient in lithotomy position, (2) robust motion management checks to ensure reproducibility of prostate and catheter positions in the treatment room before radiation delivery, (3) remote monitoring of patient vitals while under anesthesia, during the radiation. Initial viability of this approach was confirmed by assessing acute toxicities using the Common Terminology Criteria for Adverse Events v4.0 and American Urologic Association symptom scores.

RESULTS

We found good stability in prostate and catheter position, with less than 1 mm shifts in each direction due to patient transfer. The median baseline American Urologic Association score was 7 (3-11), which increased to 12 (7-17) at 4 weeks and 9 (5-14) at 3 months (p = 0.003). Common Terminology Criteria for Adverse Events ≥ grade 2 genitourinary and gastrointestinal toxicities were experienced by 7% and 0% patients, respectively, at 3 months posttreatment completion.

CONCLUSIONS

Single-fraction HDR prostate BT can be delivered safely in an unshielded OR facility with a distant shielded treatment room using rigorous motion management checks and supplementary procedural equipment.

PIK3CA mutation and CNV status and post-chemoradiotherapy survival in patients with cervical cancer

PURPOSE

This study aimed to describe the prognostic value of PI3K/AKT pathway mutations in a large cohort of patients with cervical cancer.

EXPERIMENTAL DESIGN

Patients with pre-treatment archival specimens, diagnosed with FIGO stages IB-IVA cervical cancer between 1998 and 2014 and treated with radical, curative intent chemoradiotherapy (CRT) at a single center were identified. Mutational status was determined by next generation sequencing and PIK3CA copy number (CNV) was assessed by digital PCR.

RESULTS

190 patients with available pre-treatment tumor specimens were identified. Median OS and PFS were 57.4 and 46.0 months, respectively. A total of 161 tumors were successfully sequenced; 60 (37.3%) had PI3K/AKT pathway mutations, with 50 (30.1%) having PIK3CA hotspot mutations. PIK3CA CNV gain was noted in 79 (59.2%) of the 154 successfully analyzed. On univariate analysis, PIK3CA mutation was associated with poor OS (HR 1.73; 95% CI: 1.03-2.92; p = .037) but not PFS (HR 1.38; 0.84-2.28; p = .204). Absence of any PI3K/AKT pathway mutation was associated with improved OS (HR 1.68; 1.01-2.81; p = .046) but not PFS (HR 1.50; 0.93-2.43; p = .202). Associations were not maintained when adjusting for clinical factors. On univariate analysis, PIK3CA mutation positive, CNV normal tumors were associated with poorer OS (HR 2.55; 1.18-5.50; p = .017) and trend to worse PFS (HR 1.87; 0.90-3.83; p = .094) when compared to those with CNV gain and wildtype PIK3CA.

CONCLUSIONS

PI3K/AKT pathway mutations are common in cervical cancer. Consideration of PIK3CA mutational status with CNV status may be important in predicting outcome in cervical cancer patients.

Does ADT benefit unfavourable intermediate risk prostate cancer patients treated with brachytherapy boost and external beam radiotherapy? A propensity-score matched analysis

PURPOSE

To investigate the role of androgen deprivation therapy (ADT) in unfavorable intermediate risk (UIR) prostate cancer patients treated with high-dose rate (HDR) brachytherapy (BT) boost.

MATERIAL AND METHODS

Data from 326 consecutive NCCN UIR prostate cancer patients treated in a single institution from 2009 to 2016 with 15 Gy HDR-BT boost plus 37.5 Gy external beam radiotherapy (EBRT) in 15 fractions to prostate and proximal seminal vesicles were retrospectively collected. Baseline information was collected and patients receiving vs. not receiving ADT were matched using a propensity-score model. Primary endpoint was biochemical-failure-free survival (BFFS). Kaplan-Meier estimates and stratified log-rank tests (adjusting for matched design) were used to compare BFFS, castration-resistance (CRFS) and metastasis free survival (MFS) outcomes between both groups.

RESULTS

A total of 326 patients were included in the analysis of which 52 ADT patients were matched to 104 non-ADT patients in a 1:2 ratio. Median follow-up was 3.4 years and 5.5 years for ADT and non-ADT respectively. No significant baseline differences were observed. ADT was used for a median total time of 6 months (interquartile range [IQR]: 4-6) and delivered a median time of 2.7 months (IQR: 1.7-4.3) prior to HDR-BT. BFFS was significantly improved in the ADT group (stratified log-rank: p = 0.043) with 3-year and 6-year BFFS of 98% and 90% for the ADT group and 92% and 82% for the non-ADT group, respectively. No significant differences were detected for CRFS or MFS.

CONCLUSION

Short-term ADT increased BFFS in UIR prostate cancer patients treated with HDR-BT boost plus EBRT.

Analysis of outcomes after non-contour-based dose painting of dominant intra-epithelial lesion in intra-operative low-dose rate brachytherapy

Purpose

To compare the outcomes of patients with intermediate risk prostate cancer (IR-PCa) treated with low-dose rate I-125 seed brachytherapy (LDR-BT) and targeted dose painting of a histologic dominant intra-epithelial lesion (DIL) to those without a DIL.

Methods

455 patients with IR-PCa were treated at a single center with intra-operatively planned LDR-BT, each following the same in-house dose constraints. Patients with a DIL on pathology had hot spots localized to that region but no specific contouring during the procedure.

Results

396 (87%) patients had a DIL. Baseline tumor characteristics and overall prostate dosimetry were similar between patients with and without DIL except the median number of biopsy cores taken: 10 (10–12) vs 12 (10–12) (p = 0.002).

19 (5%) and 18 (5%) of patients with and 1 (2%) and 0 (0%) of those without DIL experienced CTCAE grade 2 and 3 toxicity respectively. Overall, toxicity grade did not significantly correlate with presence of DIL (p = 0.10).

Estimated 7-year freedom from biochemical failure (FFBF) was 84% (95% confidence interval: 79–89) and 70% (54–89) in patients with and without a DIL (log-rank p = 0.315). In DIL patients, cox regression revealed location of DIL (“Base” vs “Apex” HR: 1.03; 1.00–1.06; p = 0.03) and older age (70 vs 60 HR: 1.62; 1.06–2.49; p = 0.03) was associated with poor FFBF.

Conclusions

Targeting DIL through dose painting during intraoperatively planned LDR-BT provided no statistically significant change in FFBF. Patients with DILs in the prostate base had slightly lower FFBF despite DIL boost.

Comparison of CTVHR and organs at risk contours between TRUS and MR images in IB cervical cancers: a proof of concept study

Purpose

To compare CTV_HR and OAR dimensions and inter-rater agreement between magnetic resonance (MR) and trans-rectal ultrasound (TRUS) images in IB cervical cancer patients.

Methods

IB cervical cancer patients treated with (chemo)radiotherapy plus MR-guided brachytherapy (BT) were prospectively enrolled in this study. Radiation oncologists contoured CTV_HR and OARs in pre-BT MR images (MRI) and intra-operative TRUS images. These contours were subsequently compared in regard to volume and dimension. Contour inter-rater agreement analysis was also investigated using kappa index (KI). Stata 15.0 was used for statistical analysis and a p-value < 0.05 was considered statistically significant.

Results

TRUS CTV_HR volumes were statistically smaller than the respective MRI contoured volumes. TRUS CTV_HR thickness was found to be consistently smaller than MRI contours in all patients. No statistical difference was seen in width and height between the two different imaging modalities. MRI contours had a median KI of 0.66 (range: 0.56–0.77) while TRUS-based contours had a median KI of 0.64 (range: 0.47–0.77). Bladder and rectum had very satisfactory KI in both imaging modalities. Vaginal contours had moderate agreement in MR (0.52) and in TRUS images (0.58).

Conclusion

TRUS images allow good visualization of CTV_HR and OARs in IB cervical cancer patients. Inter-rater contour variability was comparable between TRUS and MR images. TRUS is a promising modality on its own for image-guided BT.

Using infrared depth-sensing technology to improve the brachytherapy operating room experience

PURPOSE

The purpose of this study was to discuss the merits of using depth-sensing infrared camera technology in the brachytherapy operating room during interstitial brachytherapy for gynecologic malignancies.

MATERIALS AND METHODS

The infrared depth-sensing camera from a Microsoft Kinect that had been adapted for surgical use was introduced into a high-volume interstitial brachytherapy operating room. Brachytherapists then used the touchless, gestural interface to review preoperative MRI in real time to guide needle insertion.

RESULTS

The interface was used for 10 consecutive procedures by 4 separate brachytherapists. The initial training and adjustment to the technology was variable among brachytherapists. All brachytherapists found the controls intuitive and were able to successfully navigate MRI on the system after 1, 30, 30, and 45 min. Qualitatively, brachytherapists found the system helpful for interpretation of intraoperative ultrasound imaging. Furthermore, it ensured adequate needle positioning and deposition was maintained for large tumors. Surgeons involved in its use agreed on potential for considerable benefit when performing interstitial brachytherapy.

CONCLUSIONS

Adapting this technology for use in the brachytherapy suite provided a higher level of comfort with interstitial catheter placement. This novel tool or similar technology might be considered within other brachytherapy suites.

Establishing a simulation-based education program for radiation oncology learners in permanent seed implant brachytherapy: Building validation evidence

PURPOSE

The purpose of this study was to establish a simulation-based education program for radiation oncology learners in permanent seed implant brachytherapy. The first step in formalizing any education program is a validation process that builds evidence-based verification that the learning environment is appropriate.

METHODS AND MATERIALS

The primary education task allowed practitioners to use an anthropomorphic breast phantom to simulate a permanent seed implant brachytherapy delivery. Validation evidence is built by generating data to assess learner and expert cohorts according to their proficiency. Each practitioner's performance during the simulation was evaluated by seed placement accuracy, procedural time-to-complete, and two qualitative evaluation tools-a global rating scale and procedural checklist.

RESULTS

The average seed placement accuracy (±SD) was 8.1 ± 3.5 mm compared to 6.1 ± 2.6 mm for the learner and expert cohort, respectively. The median (range) procedural time-to-complete was 64 (60-77) minutes and 43 (41-50) minutes for the learner and expert cohort, respectively. Seed placement accuracy (student t-test, p < 0.05) and procedural time-to-complete (Mann-Whitney U-test, p < 0.05) were statistically different between the cohorts. In both the global rating scale and procedural checklist, the expert cohort demonstrated improved proficiency compared to the learner cohort.

CONCLUSIONS

This validation evidence supports the utilization of this simulation environment toward appropriately capturing the delivery experience of practitioners. The results demonstrate that, in all areas of evaluation, expert cohort proficiency was superior to learner cohort proficiency. This methodology will be used to establish a simulation-based education program for radiation oncology learners in permanent seed implant brachytherapy.