Defining radio-recurrent intra-prostatic target volumes using PSMA-targeted PET/CT and multi-parametric MRI.

PURPOSE: Our purpose was to evaluate intra-prostatic cancer volumes for salvage radiotherapy in men with recurrent prostate cancer confined to the prostate post-primary radiotherapy using mpMRI and 18F-DCFPyL PET/CT (PET). METHODS: Men with biochemical failure post-primary radiotherapy were enrolled in a multi-centre trial investigating mpMRI and PET. All men with isolated intra-prostatic recurrence are included in this secondary analysis. The intra-prostatic gross tumour volume (GTV) was manually delineated on mpMRI and was also delineated on PET using three methods: 1. manually, 2. using a 30% threshold of maximum intra-prostatic standard uptake value (SUVmax), and 3. using a 67% threshold of this SUVmax. Clinical target volumes (CTV) including expansions on each GTV were generated. Conformity indices were performed between the mpMRI CTV and each PET CTV. Correlation with biopsy and clinical outcomes were performed. RESULTS: Of the 36 men included, 30 (83%) had disease in two quadrants or less using the combination of mpMRI and PET. Mean target volume (union of CTV on mpMRI and CTV manually delineated on PET) was 12.2 cc (49% of prostate gland volume). 12/36 (33%) men had a biopsy. Per-patient sensitivity was 91% for mpMRI and 82% for PET. CONCLUSIONS: mpMRI and PET provide complementary information for delineation of intra-prostatic recurrent disease. Union of CTV on mpMRI and PET is often less than 50% of the prostate, suggesting this imaging could help define a target for focal salvage therapy.

Utilization of Salvage and Systemic Therapies for Recurrent Prostate Cancer as a Result of 18F-DCFPyL PET/CT Restaging.

PURPOSE: Our purpose was to investigate the effect of the addition of prostate-specific membrane antigen (PSMA)-targeted positron emission tomography/computed tomography (PET/CT) in patients with recurrent prostate cancer post-primary radiation therapy. METHODS AND MATERIALS: A prospective, multi-institutional clinical trial evaluated 2-(3-{1-carboxy-5-[(6-[18F]fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid (18F-DCFPyL) PET/CT restaging in 79 men with recurrent prostate cancer post-primary radiation therapy. We report actual patient management and compare this with proposed management both before and after PSMA-targeted PET/CT. RESULTS: Most patients (59%) had a major change in actual management compared with pre-PET/CT proposed management. The rate of major change was underestimated by immediately post-PET/CT surveys (32%). Eighteen patients with PSMA avidity in the prostate gland suspicious for malignancy had a prostate biopsy. Sensitivity, specificity, and positive predictive values of PSMA uptake in the prostate were 86%, 67%, and 92%, respectively. Thirty percent of patients had directed salvage therapy and 41% underwent systemic therapy. Eleven out of 79 patients (14%) had high-dose-rate brachytherapy alone for local recurrence, and 91% were free of recurrence at a median follow-up of 20 months. CONCLUSIONS: Most patients had a major change in actual management compared with pre-PSMA-targeted PET/CT planned management, and this was underestimated by post-PET/CT questionnaires.

Is hypofractionated whole pelvis radiotherapy (WPRT) as well tolerated as conventionally fractionated WPRT in prostate cancer patients? The HOPE trial.

BACKGROUND: Patients with high-risk prostate cancer are at increased risk of lymph node metastasis and are thought to benefit from whole pelvis radiotherapy (WPRT). There has been recent interest in the use of hypofractionated radiotherapy in treating prostate cancer. However, toxicity and cancer outcomes associated with hypofractionated WPRT are unclear at this time. This phase II study aims to investigate the impact in quality of life associated with hypofractionated WPRT compared to conventionally fractionated WPRT. METHODS: Fifty-eight patients with unfavourable intermediate-, high- or very high-risk prostate cancer will be randomized in a 1:1 ratio between high-dose-rate brachytherapy (HDR-BT) + conventionally fractionated (45 Gy in 25 fractions) WPRT vs. HDR-BT + hypofractionated (25 Gy in 5 fractions) WPRT. Randomization will be performed with a permuted block design without stratification. The primary endpoint is late bowel toxicity and the secondary endpoints include acute and late urinary and sexual toxicity, acute bowel toxicity, biochemical failure-, androgen deprivation therapy-, metastasis- and prostate cancer-free survival of the hypofractionated arm compared to the conventionally fractionated arm. DISCUSSION: To our knowledge, this is the first study to compare hypofractionated WPRT to conventionally fractionated WPRT with HDR-BT boost. Hypofractionated WPRT is a more attractive and convenient treatment approach, and may become the new standard of care if demonstrated to be well-tolerated and effective. TRIAL REGISTRATION: This trial was prospectively registered in ClinicalTrials.gov as NCT04197141 on December 12, 2019.

Genetic and clinical predictors of arthralgia during letrozole or anastrozole therapy in breast cancer patients.

PURPOSE: Female patients with breast cancer frequently develop arthralgia when treated with aromatase inhibitors (AI). Although the mechanism of AI-induced arthralgia is unknown, potential biomarkers have been identified. The purpose of this study was to investigate the clinical and genetic predictors of AI-induced arthralgia in a prospective cohort of patients with estrogen receptor-positive breast cancer. METHODS: One hundred and ninety-six patients were enrolled at initiation of AI therapy with either letrozole or anastrozole. Patients completed two validated self-report questionnaires assessing pain, stiffness, and physical function at baseline, and repeated the questionnaires at two and at six months after the initiation of treatment with an AI. Germline DNA of all patients was genotyped for seven single-nucleotide polymorphisms (SNPs) previously identified by genetic screens and genome-wide association studies as associated with AI-induced arthralgia. RESULTS: More than 50% of the study group experienced arthralgia symptoms. Genetic analysis revealed that four SNPs, in CYP19A1 (rs4775936) and ESR1 (rs9322336, rs2234693, rs9340799), were associated with the development of arthralgia (adjusted P = 0.016, 0.018, 0.017, 0.047). High body mass index (BMI) was also associated with the development of arthralgia symptoms (adjusted P = 0.001). Patients prescribed letrozole were significantly more likely to develop arthralgia than patients on anastrozole (P = 0.018), and also more likely to discontinue AI therapy due to arthralgia. The CYP19A1 (rs4775936) SNP was significantly associated with discontinuation of therapy due to intolerable arthralgia. CONCLUSIONS: Our results suggested that BMI and AI drug (letrozole versus anastrozole) were clinical predictors of arthralgia, while genetic variants rs4775936, rs9322336, rs2234693, and rs9340799 were genetic predictors of AI-induced arthralgia. Significantly, rs4775936 was also a predictor of discontinuation of therapy.

A Prospective Study of 18F-DCFPyL PSMA PET/CT Restaging in Recurrent Prostate Cancer following Primary External Beam Radiotherapy or Brachytherapy.

PURPOSE: Radio-recurrent prostate cancer is typically detected by a rising prostate-specific antigen and may reflect local or distant disease. Positron emission tomography (PET) radiotracers targeting prostate-specific membrane antigen, such as 18F-DCFPyL have shown promise in restaging men with recurrent disease postprostatectomy but are less well characterized in the setting of radio-recurrent disease. METHODS AND MATERIALS: A prospective, multi-institutional study was conducted to evaluate the effect of 18F-DCFPyL PET/computed tomography (CT) when added to diagnostic imaging (DI; CT abdomen and pelvis, bone scan, multiparametric magnetic resonance imaging pelvis) for men with radio-recurrent prostate cancer. All men were imaged with DI and subsequently underwent 18F-DCFPyL PET/CT with local and central reads. Tie break reads were performed as required. Management questionnaires were completed after DI and again after 18F-DCFPyL PET/CT. Discordance in patterns of disease detected with 18F-DCFPyL PET/CT versus DI and changes in management were characterized. RESULTS: Seventy-nine men completed the study. Most men had T1 disease (62%) and Gleason score <7 (95%). Median prostate-specific antigen at diagnosis was 7.4 ng/mL and at relapse was 4.8 ng/mL. DI detected isolated intraprostatic recurrence in 38 out of 79 men (48%), regional nodal recurrence in 9 out of 79 (11%), distant disease in 12 out of 79 (15%), and no disease in 26 out of 79 (33%). 18F-DCFPyL PET/CT detected isolated intraprostatic recurrence in 38 out of 79 men (48%), regional nodal recurrence in 21 out of 79 (27%), distant disease in 24 out of 79 (30%), and no disease in 10 out of 79 (13%). DI identified 8 out of 79 (10%) patients to have oligometastatic disease, compared with 21 out of 79 (27%) with 18F-DCFPyL PET/CT. 18F-DCFPyL PET/CT changed proposed management in 34 out of 79 (43%) patients. CONCLUSIONS: 18F-DCFPyL PET/CT identified extraprostatic disease in twice as many men with radio-recurrent prostate cancer compared with DI and detected a site of recurrence in 87% of men compared with 67% with DI. Furthermore, 18F-DCFPyL PET/CT identified potentially actionable disease (prostate only recurrence or oligometastatic disease) in 75% of men and changed proposed management in 43% of men.

A Phase I/II Trial of Fairly Brief Androgen Suppression and Stereotactic Radiation Therapy for High-Risk Prostate Cancer (FASTR-2): Preliminary Results and Toxicity Analysis.

PURPOSE: FASTR was designed to provide a compact treatment course for high-risk prostate cancer patients but was discontinued because of excess toxicity. We present the results of FASTR-2, which used a lower dose to the prostate (35 Gy vs 40 Gy), smaller posterior PTV margin (4 mm vs 5 mm) and omitted nodal radiation to lower the volumes of rectum receiving high and intermediate doses compared with FASTR. Gastrointestinal (GI) and genitourinary (GU) toxicities at baseline, 6 weeks, 6 months, and 1 year and biochemical control rates are presented. METHODS AND MATERIALS: Eligibility included high-risk prostate cancer (cT3/4, prostate-specific antigen >20 or Gleason Score ≥8), age ≥70 or refused standard treatment, and no evidence of metastatic disease. Patients received 18 months of androgen deprivation therapy starting 2 months before radiation. Clinical target volume was defined as prostate plus proximal 1-cm seminal vesicles. PTV was a nonuniform expansion around clinical target volume (4 mm posteriorly, 5 mm in all other directions). Volumetric arc therapy was used for treatment delivery (35 Gy delivered in 5 weekly fractions of 7 Gy each), and cone beam computed tomography with soft tissue matching (no fiducial placement) was used for daily image guidance. Toxicity was assessed at 6 weeks, 6 months, and 1 year according to Common Toxicity Criteria. RESULTS: In the study, 30 patients were enrolled in FASTR-2 between 2015 and 2017. Two patients were withdrawn owing to ineligibility after enrollment. One patient (3.7%) reported grade 2 GI toxicity at 6 weeks. There was no reported grade ≥2 GI toxicity at 6 months or 1 year. There were no reported episodes of rectal bleeding. Four patients (14.8%), 5 patients (17.9%), and 5 patients (21.7%) reported grade 2 GU toxicity at 6 weeks, 6 months, and 1 year, respectively. There were no reported cases of grade ≥3 GU toxicity. The most common toxicities were nocturia and urinary frequency or urgency. CONCLUSIONS: FASTR-2 was more tolerable than FASTR, with no grade ≥3 toxicities reported, in keeping with expectations based on our previous FASTR analysis. Long-term follow-up is necessary to ensure disease control and toxicity outcomes are comparable to conventional high-risk treatment paradigms.

Reducing the dose of gadolinium-based contrast agents for DCE-MRI guided SBRT: The effects on inter and intra observer variability for preoperative target volume delineation in early stage breast cancer patients.

BACKGROUND AND PURPOSE: This study aimed to determine the effects of reducing the dose of contrast agent (CA) in a DCE-MRI scan on inter- and intra-observer variability in the context of MRI-guided target volume delineation for stereotactic body radiation therapy of early stage breast cancer patients. This is in hopes of reducing risks to patients due to findings of residual CA in brain and bone. MATERIALS AND METHODS: Twenty-three patients receiving neoadjuvant radiation therapy were enrolled. Five observers delineated the gross target volume (GTV) using DCE-MRI for guidance. 14/23 patients received the full clinical dose of CA and 9/23 received half. Clinical target volumes (CTV) were created through a 0.5 cm uniform expansion. Several metrics were used to quantify the inter and intra-observer reliability including differences in delineation volume and the reliability coefficient. RESULTS: There were no significant differences in the volume, though half contrast patients had a lower median for both the GTV and CTV (difference of 0.26 cm3 and 1.27 cm3, respectively). All indicated a high degree of agreement between and within observers for both dose groups. However, the full dose group had a greater inter-observer variability, most likely due to the full CA causing more pronounced enhancement in the periphery. CONCLUSIONS: Reducing the dose of contrast agent did not significantly alter inter- or intra-observer variability. These results have prompted our centre to reduce the dose of gadolinium in all patients enrolled in the SIGNAL trial.

A Phase II Multi-institutional Clinical Trial Assessing Fractionated Simultaneous In-Field Boost Radiotherapy for Brain Oligometastases.

Purpose/Objective Published preclinical and phase I clinical trial data suggest that fractionated lesional radiotherapy with 60 Gy in 10 fractions can serve as an alternative approach to single fraction radiosurgical boost for brain oligometastases.  Methods and Materials A phase II clinical trial (NCT01543542) of a total of 60 Gy in 10 fractions of lesional (one to three) radiotherapy (given simultaneously with whole-brain helical tomotherapy with 30 Gy in 10 fractions) was conducted at five institutions. We hypothesized that fractionated radiotherapy would be considered unsuitable if the median overall survival (OS) was degraded by two months or if six-month intracranial control (ICC) and intracranial lesion (ILC) were inferior by 10% compared with the published RTOG 9508 results. Results A total of 87 patients were enrolled over a 4.5-year accrual period. Radiological lesion and extralesional central nervous system progression were documented in 15/87 (17%) and 11/87 (13%) patients, respectively. Median OS for all patients was 5.4 months. Six-month actuarial estimates of ICC and ILC were 78% and 89%, respectively. However, only the ILC estimate achieved statistical significance (p=0.02), demonstrating non-inferiority to the a priori historical controls (OS: p=0.09, ICC=0.31). Two patients developed suspected asymptomatic radionecrosis. Conclusions The phase II estimates of ILC were demonstrated to be non-inferior to the results of the RTOG 9508.

Letrozole concentration is associated with CYP2A6 variation but not with arthralgia in patients with breast cancer.

PURPOSE: The aromatase inhibitor (AI) letrozole is a first-line drug in the adjuvant treatment of breast cancer in postmenopausal women. Adherence to AI therapy, including letrozole, remains problematic due to the development of debilitating AI-induced arthralgia. Letrozole is metabolized in the liver by CYP2A6. It remains unknown if plasma letrozole levels or CYP2A6 genetic variation is associated with the development of arthralgia. METHODS: We enrolled 126 female breast cancer patients initiated on letrozole therapy and prospectively collected blood samples at baseline and two follow-up time points to determine letrozole plasma concentrations and CYP2A6 genotype. At each visit, participants completed two validated questionnaires to assess the severity of arthralgia symptoms. RESULTS: More than half (55%) of patients experienced a significant increase in their arthralgia symptoms after initiation of treatment. The clinical variables of body mass index (P = 0.0003) and age (P = 0.0430) were negatively and positively associated with plasma letrozole concentrations, respectively. CYP2A6 genotype was significantly associated with letrozole levels (P < 0.0001), and increased plasma letrozole levels were observed in patients with CYP2A6 reduced-function genotypes. Plasma levels of letrozole and CYP2A6 genotype were not significantly associated with a change in pain score from baseline. CONCLUSIONS: CYP2A6 genotype was a significant predictor of letrozole plasma levels, but was not associated with the development of arthralgia.

Chemoradiotherapy in octogenarians as primary treatment for muscle-invasive bladder cancer.

INTRODUCTION: While radical cystectomy is the gold standard for muscle-invasive bladder cancer (MIBC), in octogenarians cystectomy results in a higher perioperative mortality rate (6.8-11.1%) than in younger patients (2.2%). Trimodality therapy is a bladder-sparing regimen composed of transurethral resection of bladder tumour (TURBT) and chemoradiotherapy, with intent for salvage cystectomy, and has a 62.5-90% initial complete response rate. In this study, we evaluate TURBT and chemoradiotherapy without salvage cystectomy in medically inoperable octogenarian patients. METHODS: We identified a retrospective cohort of patients aged 80-89 years with invasive urothelial carcinoma who received combination chemoradiotherapy between 2008 and June 2014. Outcomes were evaluated by Kaplan-Meier (KM) and Cox regression. RESULTS: In 40 patients, the mean age was 84.5 years (interquartile range [IQR] 83-86). Seventeen patients received hypofractionated, low-dose radiotherapy (LD) (37.5-40 Gy), while 23 received conventionally fractionated radiotherapy (high-dose [HD]) (50-65 Gy). Mean overall survival (OS) was 20.7 months (IQR 12.75-23.25), while mean recurrence-free survival (RFS) was 13.75 months (IQR 3.75-16.5). Patients receiving HD radiotherapy showed improved OS and local RFS (LRFS) without significant differences in Grade 3-4 toxicities. Univariate Cox regression identified hydronephrosis as a predictor of worse OS and local recurrence and HD radiotherapy as a predictor of improved OS and local recurrence rates. Multivariate Cox regression identified hydronephrosis to be a significant predictor of LRFS. CONCLUSIONS: Primary chemoradiotherapy for inoperable patients with MIBC resulted in a three-year OS of 54.9% (comparable to cystectomy) and three-year RFS of 42.3%. Superior outcomes were associated with more aggressive chemoradiotherapy treatment. The results of the local control subanalyses in this study are hypothesis-generating due to the limited patient numbers in the cohort.

A Single Institution Consensus on the Use of Sequential or Concurrent Hormonal Therapy for Breast Cancer Patients Receiving Radiation Therapy.

BACKGROUND AND OBJECTIVES: For hormone-sensitive breast cancers, treatment with breast-conserving surgery, tamoxifen, or aromatase inhibitors, along with adjuvant radiation, is the mainstay of therapy. The ideal timing of hormonal and radiation treatment is not well defined, and there is a significant degree of practice variability between concurrent and sequential treatment regimes. This variability can cause confusion amongst the clinical team resulting in contradictory recommendations, loss of patient trust, and the potential for missed initiation of hormonal therapy. METHODS: To address this question, a systematic review of the literature was conducted and presented to the breast cancer multidisciplinary team at the London Regional Cancer Center. A three-round modified Delphi method was used to obtain a consensus on a series of a priori determined statements. RESULTS: With the currently available evidence, the consensus was that hormonal therapy should be given sequentially after radiation. This will limit potential overlapping adverse effects between hormonal therapy and radiation that may decrease completion of treatment. The sequential approach has not been associated with any harm in clinical outcomes, and there is some suggestion of increased toxicity with concurrent use. However, in patients at high risk of distant recurrence, they felt it would be reasonable to consider concurrent treatment to avoid any delay in therapy. CONCLUSION: The consensus of our institution to utilize a sequential approach will standardize the treatment decisions and reduce the risk of failing to initiate hormonal therapy. Despite the lack of level 1 evidence, the Delphi methodology did provide a high level of confidence for our group to choose the sequential approach. The consensus was developed after a review of the literature revealed that there was no clear superiority of one schedule over the other and evidence that concurrent treatment may increase adverse events.

Assessment of function and quality of life in a phase II multi-institutional clinical trial of fractionated simultaneous in-field boost radiotherapy for patients with 1-3 metastases.

We examined functional outcomes and quality of life of whole brain radiotherapy (WBRT) with integrated fractionated stereotactic radiotherapy boost (FSRT) for brain metastases treatment. Eighty seven people with 1-3 brain metastases (54/87 lung primary, 42/87 single brain metastases) were enrolled on this Phase II trial of WBRT (30 Gy/10) + simultaneous FSRT, (60 Gy/10). Median overall follow-up and survival was 5.4 months, 6 month actuarial intra-lesional control was 78 %; only 1 patient exhibited grade 4 toxicity (worsened seizures); most treatment related toxicity was grade 1 or 2; 2/87 patients demonstrated asymptomatic radiation necrosis on follow-up imaging. Mean (Min-Max) baseline KPS, Mini Mental Status Exam (MMSE) and FACT-BR quality of life were 83 (70-100), 28 (21-30) and 143 (98-153). Lower baseline MMSE (but not KPS or FACT-Br) was associated with worse survival after adjusting for age, number of metastases, primary and extra-cranial disease status. Crude rates of deterioration (>10 points decrease from baseline for KPS and FACT-Br, MMSE fall to <27) ranged from 26 to 38 % for KPS, 32-59 % for FACT-Br and 0-16 % for MMSE depending on the time-point assessed with higher rates generally noted at earlier time points (≤6 months post-treatment). Using a linear mixed models analysis, significant declines from baseline were noted for KPS and FACT-Br (largest effects at 6 weeks to 3 months) with no significant change in MMSE. The effects on function and quality of life of this integrated treatment of WBRT + simultaneous FSRT were similar to other published series combining WBRT + radiosurgery.

A Phase 1/2 Trial of Brief Androgen Suppression and Stereotactic Radiation Therapy (FASTR) for High-Risk Prostate Cancer.

PURPOSE: To initiate a phase 1/2 trial to examine the tolerability of a condensed combined-modality protocol for high-risk prostate cancer. METHODS AND MATERIALS: Men scoring ≥3 on the Vulnerable Elderly Scale (VES) or refusing conventionally fractionated treatment for high-risk prostate cancer were eligible to participate. Androgen suppression was delivered for 12 months, and radiation therapy was delivered using 25 Gy to pelvic nodes delivered synchronously with 40 Gy to the prostate given as 1 fraction per week over 5 weeks. The phase 1 component included predetermined stopping rules based on 6-month treatment-related toxicity, with trial suspension specified if there were ≥6 of 15 patients (40%) or ≥3 of 15 (20%) who experienced grade ≥2 or ≥3 gastrointestinal (GI) or genitourinary (GU) toxicity, respectively. RESULTS: Sixteen men were enrolled, with 7 men meeting the criteria of VES ≥3 and 9 men having a VES <3 but choosing the condensed treatment. One man was not treated owing to discovery of a synchronous primary rectal cancer. Four patients (26%) experienced grade ≥2 toxicity at 6 weeks after treatment. There were 9 of 15 (60%) who experienced grade ≥2 GI or GU toxicity and 4 of 15 (26%) grade ≥3 GI or GU toxicity at 6 months, and 5 of 15 (30%) grade ≥2 GI and GU toxicity at 6 months. A review of the 15 cases did not identify any remedial changes, thus the phase 1 criteria were not met. CONCLUSION: This novel condensed treatment had higher than anticipated late toxicities and was terminated before phase 2 accrual. Treatment factors, such as inclusion of pelvic lymph node radiation therapy, planning constraints, and treatment margins, or patient factors related to the specific frail elderly population may be contributing.

Evaluating the impact of a Canadian national anatomy and radiology contouring boot camp for radiation oncology residents.

BACKGROUND: Radiation therapy treatment planning has advanced over the past 2 decades, with increased emphasis on 3-dimensional imaging for target and organ-at-risk (OAR) delineation. Recent studies suggest a need for improved resident instruction in this area. We developed and evaluated an intensive national educational course ("boot camp") designed to provide dedicated instruction in site-specific anatomy, radiology, and contouring using a multidisciplinary (MDT) approach. METHODS: The anatomy and radiology contouring (ARC) boot camp was modeled after prior single-institution pilot studies and a needs-assessment survey. The boot camp incorporated joint lectures from radiation oncologists, anatomists, radiologists, and surgeons, with hands-on contouring instruction and small group interactive seminars using cadaveric prosections and correlative axial radiographs. Outcomes were evaluated using pretesting and posttesting, including anatomy/radiology multiple-choice questions (MCQ), timed contouring sessions (evaluated relative to a gold standard using Dice similarity metrics), and qualitative questions on satisfaction and perceived effectiveness. Analyses of pretest versus posttest scores were performed using nonparametric paired testing. RESULTS: Twenty-nine radiation oncology residents from 10 Canadian universities participated. As part of their current training, 29%, 75%, and 21% receive anatomy, radiology, and contouring instruction, respectively. On posttest scores, the MCQ knowledge scores improved significantly (pretest mean 60% vs posttest mean 80%, P<.001). Across all contoured structures, there was a 0.20 median improvement in students' average Dice score (P<.001). For individual structures, significant Dice improvements occurred in 10 structures. Residents self-reported an improved ability to contour OARs and interpret radiographs in all anatomic sites, 92% of students found the MDT format effective for their learning, and 93% found the boot camp more effective than educational sessions at their own institutions. All of the residents (100%) would recommend this course to others. CONCLUSIONS: The ARC boot camp is an effective intervention for improving radiation oncology residents' knowledge and understanding of anatomy and radiology in addition to enhancing their confidence and accuracy in contouring.

Ultrasound surveillance for thyroid malignancies in survivors of childhood cancer following radiotherapy: a single institutional experience.

BACKGROUND: Survivors of childhood cancer (SCC) who have received radiotherapy to the head, neck, and upper thorax are at higher risk of developing subsequent thyroid malignancies. As part of the post treatment long-term follow-up protocol, the current Children's Oncology Group guideline recommends surveillance by annual palpation; however, thyroid nodules are difficult to detect by physical examinations alone, and potentially malignancy-harboring nodules may be undetected. Since thyroid ultrasound is a sensitive and noninvasive procedure, it was incorporated in our institutional follow-up protocol. The aim of this study was to examine the outcome of ultrasound screening in this high-risk population. The following describes our experience from 2007 to 2013. METHODS: A retrospective chart review was conducted on survivors enrolled in our follow-up program. SCC who have received direct or scattered radiation to the thyroid gland, and who were ≥10 years from the diagnosis of primary childhood cancer were considered to be at-risk. RESULTS: Seventy-eight survivors met the inclusion criteria and were screened. Thyroid ultrasound detected thyroid nodule(s) in 46 patients (59%), 17 of which had nodule(s) between 5 and 10 mm (22%), and 15 patients had nodules ≥10 mm (19%). Fourteen patients (18%) underwent fine-needle aspiration biopsy. Six patients (8%) underwent surgery, and 5 (6%) had confirmed papillary carcinoma. At the time of the first ultrasound, thyroid nodules of various sizes were found. However, over time, these nodules demonstrated slow growth rates. CONCLUSIONS: Incorporation of thyroid ultrasound into routine follow-up of high-risk SCC may aid in the detection of thyroid malignancies that are not clinically apparent. The use of ultrasound allows detailed characterization of the thyroid nodule and reliable monitoring of nodule progression. In SCC without suspicious nodule(s), it may be reasonable to perform screening ultrasounds less frequently due to the slow growth rate of thyroid nodules. However, in those with suspicious features, surgical work-up resulted in the removal of a high number of malignancies, with few unnecessary surgeries and complications.

A multiphase validation of atlas-based automatic and semiautomatic segmentation strategies for prostate MRI.

PURPOSE: To perform a rigorous technological assessment and statistical validation of a software technology for anatomic delineations of the prostate on MRI datasets. METHODS AND MATERIALS: A 3-phase validation strategy was used. Phase I consisted of anatomic atlas building using 100 prostate cancer MRI data sets to provide training data sets for the segmentation algorithms. In phase II, 2 experts contoured 15 new MRI prostate cancer cases using 3 approaches (manual, N points, and region of interest). In phase III, 5 new physicians with variable MRI prostate contouring experience segmented the same 15 phase II datasets using 3 approaches: manual, N points with no editing, and full autosegmentation with user editing allowed. Statistical analyses for time and accuracy (using Dice similarity coefficient) endpoints used traditional descriptive statistics, analysis of variance, analysis of covariance, and pooled Student t test. RESULTS: In phase I, average (SD) total and per slice contouring time for the 2 physicians was 228 (75), 17 (3.5), 209 (65), and 15 seconds (3.9), respectively. In phase II, statistically significant differences in physician contouring time were observed based on physician, type of contouring, and case sequence. The N points strategy resulted in superior segmentation accuracy when initial autosegmented contours were compared with final contours. In phase III, statistically significant differences in contouring time were observed based on physician, type of contouring, and case sequence again. The average relative timesaving for N points and autosegmentation were 49% and 27%, respectively, compared with manual contouring. The N points and autosegmentation strategies resulted in average Dice values of 0.89 and 0.88, respectively. Pre- and postedited autosegmented contours demonstrated a higher average Dice similarity coefficient of 0.94. CONCLUSION: The software provided robust contours with minimal editing required. Observed time savings were seen for all physicians irrespective of experience level and baseline manual contouring speed.

Assessment and improvement of radiation oncology trainee contouring ability utilizing consensus-based penalty metrics.

INTRODUCTION: The objective of this study was to develop and assess the feasibility of utilizing consensus-based penalty metrics for the purpose of critical structure and organ at risk (OAR) contouring quality assurance and improvement. METHODS: A Delphi study was conducted to obtain consensus on contouring penalty metrics to assess trainee-generated OAR contours. Voxel-based penalty metric equations were used to score regions of discordance between trainee and expert contour sets. The utility of these penalty metric scores for objective feedback on contouring quality was assessed by using cases prepared for weekly radiation oncology radiation oncology trainee treatment planning rounds. RESULTS: In two Delphi rounds, six radiation oncology specialists reached agreement on clinical importance/impact and organ radiosensitivity as the two primary criteria for the creation of the Critical Structure Inter-comparison of Segmentation (CriSIS) penalty functions. Linear/quadratic penalty scoring functions (for over- and under-contouring) with one of four levels of severity (none, low, moderate and high) were assigned for each of 20 OARs in order to generate a CriSIS score when new OAR contours are compared with reference/expert standards. Six cases (central nervous system, head and neck, gastrointestinal, genitourinary, gynaecological and thoracic) then were used to validate 18 OAR metrics through comparison of trainee and expert contour sets using the consensus derived CriSIS functions. For 14 OARs, there was an improvement in CriSIS score post-educational intervention. CONCLUSIONS: The use of consensus-based contouring penalty metrics to provide quantitative information for contouring improvement is feasible.

Circulating tumour cells in prostate cancer patients receiving salvage radiotherapy.

INTRODUCTION: Within 10 years of radical prostatectomy (RP), up to 30% of prostate cancer (PCa) patients will have a rise in prostate-specific antigen (PSA), requiring radiation therapy (RT). However, with current technology, distinction between local and distant recurrent PCa is not possible. This lack of an accurate test constrains the decision whether to offer systemic or local treatment. We hypothesise tests for detecting circulating tumour cells (CTCs) within the blood may assist with clinical decision-making and in this pilot study we investigated whether CTCs could be detected in this patient population using the CellSearch® system. MATERIALS AND METHODS: Blood samples were collected from PCa patients (n=26) prior to RT and 3 months following completion of RT. Samples were analysed for PSA level via immunoassay and CTC number using the CellSearch® system. RESULTS: CTCs could be detected in this patient population and following RT CTCs appeared to decrease. However, no association was observed between a higher PSA and an increased number of CTCs pre- or post-RT. Interestingly, patients who failed RT trended toward an increased/ unchanged number of CTCs following RT vs. a decreased number in patients with RT response. CONCLUSIONS: Our results demonstrate that CTCs can be detected in early-stage PCa and suggest the possibility that post-treatment reduction in CTC levels may be indicative of RT response . We are currently evaluating CTCs in a larger cohort of patients to validate our preliminary findings and further investigate the prognostic value of CTCs in this patient population.

Technology assessment of automated atlas based segmentation in prostate bed contouring.

BACKGROUND: Prostate bed (PB) contouring is time consuming and associated with inter-observer variability. We evaluated an automated atlas-based segmentation (AABS) engine in its potential to reduce contouring time and inter-observer variability. METHODS: An atlas builder (AB) manually contoured the prostate bed, rectum, left femoral head (LFH), right femoral head (RFH), bladder, and penile bulb of 75 post-prostatectomy cases to create an atlas according to the recent RTOG guidelines. 5 other Radiation Oncologists (RO) and the AABS contoured 5 new cases. A STAPLE contour for each of the 5 patients was generated. All contours were anonymized and sent back to the 5 RO to be edited as clinically necessary. All contouring times were recorded. The dice similarity coefficient (DSC) was used to evaluate the unedited- and edited- AABS and inter-observer variability among the RO. Descriptive statistics, paired t-tests and a Pearson correlation were performed. ANOVA analysis using logit transformations of DSC values was calculated to assess inter-observer variability. RESULTS: The mean time for manual contours and AABS was 17.5- and 14.1 minutes respectively (p = 0.003). The DSC results (mean, SD) for the comparison of the unedited-AABS versus STAPLE contours for the PB (0.48, 0.17), bladder (0.67, 0.19), LFH (0.92, 0.01), RFH (0.92, 0.01), penile bulb (0.33, 0.25) and rectum (0.59, 0.11). The DSC results (mean, SD) for the comparison of the edited-AABS versus STAPLE contours for the PB (0.67, 0.19), bladder (0.88, 0.13), LFH (0.93, 0.01), RFH (0.92, 0.01), penile bulb (0.54, 0.21) and rectum (0.78, 0.12). The DSC results (mean, SD) for the comparison of the edited-AABS versus the expert panel for the PB (0.47, 0.16), bladder (0.67, 0.18), LFH (0.83, 0.18), RFH (0.83, 0.17), penile bulb (0.31, 0.23) and rectum (0.58, 0.09). The DSC results (mean, SD) for the comparison of the STAPLE contours and the 5 RO are PB (0.78, 0.15), bladder (0.96, 0.02), left femoral head (0.87, 0.19), right femoral head (0.87, 0.19), penile bulb (0.70, 0.17) and the rectum (0.89, 0.06). The ANOVA analysis suggests inter-observer variability among at least one of the 5 RO (p value = 0.002). CONCLUSION: The AABS tool results in a time savings, and when used to generate auto-contours for the femoral heads, bladder and rectum had superior to good spatial overlap. However, the generated auto-contours for the prostate bed and penile bulb need improvement.