No abstract

A total of 50% or greater positive biopsy cores is an independent predictor of poor biochemical failure-free survival in patients treated with brachytherapy. High quality prostate brachytherapy, defined by a highest dose covering at least 90% of the prostate of 100% or greater, minimize the adverse effect of 50% or greater positive biopsy cores on time to biochemical failure.

As we develop radiation treatment planning systems for head and neck cancer patients, there is a need to identify reference patients whose anatomical structures share similar features. By finding previously treated patients or prototypical models with the most similar anatomy in the head and neck region, our prototype system can do a better job of identifying lymph node regions based on known regions predefined for similar patients. This can potentially expedite the radiation treatment planning process which currently depends on oncologists manually delineating lymph node regions for each patient slice by slice on their CT scans. Our methodology uses the identification of landmark anatomical structures from the CT scan of the cancer patient and the computation of a Hausdorff distance between these and the corresponding structures of the reference scans. The combination of these structural correspondence features and a set of global shape features provide a distance metric that can rapidly find the most similar reference patient case and thus efficiently and accurately generate the desired lymph node regions for a given test case.

Shorter gap intervals between supplemental beam radiation and brachytherapy implant are safe. Shorter gap intervals do not improve BFFS; however, they do allow for treatment completion in a more timely fashion.

ImportanceHypofractionated radiation therapy (RT) for prostate cancer has been associated with greater acute grade 2 gastrointestinal (GI) toxic effects compared with conventionally fractionated RT.ObjectiveTo evaluate whether a hyaluronic acid rectal spacer could (1) improve rectal dosimetry and (2) affect acute grade 2 or higher GI toxic effects for hypofractionated RT.Design, Setting, and ParticipantsThis randomized clinical trial was conducted from March 2020 to June 2021 among 12 centers within the US, Australia, and Spain, with a 6-month follow-up. Adult patients with biopsy-proven, T1 to T2 prostate cancer with a Gleason score 7 or less and prostate-specific antigen level of 20 ng/mL or less (to convert to μg/L, multiply by 1) were blinded to the treatment arms. Of the 260 consented patients, 201 patients (77.3%) were randomized (2:1) to the presence or absence of the spacer. Patients were stratified by intended 4-month androgen deprivation therapy use and erectile quality.Main Outcomes and MeasuresFor the primary outcome, we hypothesized that more than 70% of patients in the spacer group would achieve a 25% or greater reduction in the rectal volume receiving 54 Gy (V54). For the secondary outcome, we hypothesized that the spacer group would have noninferior acute (within 3 months) grade 2 or higher GI toxic effects compared with the control group, with a margin of 10%.ResultsOf the 201 randomized patients, 8 (4.0%) were Asian, 26 (12.9%) Black, 42 (20.9%) Hispanic or Latino, and 153 (76.1%) White; the mean (SD) age for the spacer group was 68.6 (7.2) years and 68.4 (7.3) years for the control group. For the primary outcome, 131 of 133 (98.5%; 95% CI, 94.7%-99.8%) patients in the spacer group experienced a 25% or greater reduction in rectum V54, which was greater than the minimally acceptable 70% (P < .001). The mean (SD) reduction was 85.0% (20.9%). For the secondary outcome, 4 of 136 patients (2.9%) in the spacer group and 9 of 65 patients (13.8%) in the control group experienced acute grade 2 or higher GI toxic effects (difference, −10.9%; 95% 1-sided upper confidence limit, −3.5; P = .01).Conclusions and RelevanceThe trial results suggest that rectal spacing with hyaluronic acid improved rectal dosimetry and reduced acute grade 2 or higher GI toxic effects. Rectal spacing should potentially be considered for minimizing the risk of acute grade 2 or higher toxic effects for hypofractionated RT.Trial RegistrationClinicalTrials.gov Identifier: NCT04189913

No abstract

4645 Background: Percent biopsy core positivity (%BCP) has been correlated with tumor volume, extraprostatic disease and biochemical progression free survival (bPFS) in surgical series. In an external beam series, it can predict time to progression in a subset of patients. Methods: The percentage of biopsy cores involved with cancer was determined from original pathology reports of 566 patients with clinical stage T1c-T2a, Gleason grade 7–10 and/or PSA 10–20 CaP. These patients had previously been treated on a prospective study that randomized between 20 or 44 Gy of supplemental beam radiation therapy followed by Pd-103 brachytherapy. bPFS was defined as having a serum PSA ≤0.5 ng/ml at last follow-up. Patients were censored at last follow-up if their serum PSA was still decreasing. Results: 5 year bPFS was 79% for the entire group of 566 patients and 84% for the sub-group of 333 patients with %BCP quantified. On Cox regression analysis, biological variables analyzed included PSA, PSA < or ≥ 10, Gleason score, Gleason score < or ≥8, %BCP divided into two different grouping schemes (<34, 34 through 50 and ≥50) and < or ≥50. Treatment related variables analyzed included V100, V100 < or ≥90%, D 90, D 90 < or ≥80%, supplemental beam dose of 20 or 40 Gy. On univariate analysis, significant factors were limited to: %BCP < vs. ≥50 (p = 0.004), %BCP <34 Vs. ≥50% (p = 0.006), PSA, PSA < or ≥10, Gleason score, V100 < or ≥90%, D 90. On multivariate analysis, %BCP was the only significant determinant (p = 0.006) irregardless of which stratification scheme was utilized. For %BCP ≥50%, the hazard ratio for biochemical failure was 3.6 (95% confidence interval 1.4 to 8.8). On Kaplan-Meier analysis, 5 year bPFS was 90% and 79% for patients with <50% and ≥50% cores involved respectively (p = 0.002). Conclusions: With implementation of implant techniques that uniformly meet optimal dosimetric criteria in patients felt to be at intermediate to high risk of failure based on Gleason and PSA, the percent of biopsy cores positive with malignancy emerges as the single most important factor in predicting biochemical failure. There is a statistically significant reduction in bPFS in patients with ≥50% of their core needle biopsies involved with malignancy. No significant financial relationships to disclose.

PurposeA multicenter, double‐arm, central core lab, retrospective study was performed to compare the rectal dosimetry of patients implanted with two injectable, biodegradable perirectal spacers, in conventional fractionation (CF), as well as ultrahypofractionation (UH) treatment plans.Methods and materialsFifty‐nine patients were enrolled into the study in five centers: two centers in Europe, which implanted a biodegradable balloon spacer in a total of 24 subjects and three centers in the US, which implanted the SpaceOAR in 35 subjects. Anonymized CTs (pre and post‐implantation) were reviewed by the central core lab. For VMAT CF plans rectal V50, V60, V70, and V80 were calculated. For UH plans, a corresponding rectal V22.6, V27.1, V31.37, and V36.25 were established representing 62.5%, 75%, 87.5%, and 100% of the 36.25 Gy prescribed dose.ResultsFor CF VMAT, a comparison between the balloon spacer and the SpaceOAR revealed a significant difference of 33.4% decrease in mean rectal V50 (71.9% vs. 38.5%, p < 0.001), 27.7% in mean rectal V60 (79.6% vs. 51.9%, p < 0.001), 17.1% difference in mean rectal V70 (84.1% vs. 67.0%, p = 0.001), and a significant difference of 3.0% (p = 0.019) in mean rectal V80 (87.2% vs. 84.2%). With UH analysis, the mean rectal dose reduction for the balloon spacer compared to the SpaceOAR was 79.2% and 53.3% for V27.1 (p < 0.001), 84.1% and 68.1% for V31.71 (p = 0.001), and 89.7% and 84.8% for V36.25 (p = 0.012), respectively.ConclusionRectal dosimetry is more favorable for treatment with the balloon spacer compared with SpaceOAR. Further research, particularly in the context of a prospective randomized clinical trial design, is needed to assess the acute and late toxicity experience as well as physician satisfaction with achieving symmetrical implantation, and ease of use in light of increasing clinical use.