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.

Institutional long-term outcomes at the first Canadian center performing intraoperatively planned low-dose-rate brachytherapy alone in low- and intermediate-risk prostate cancer

PURPOSE

The aim of this study is to report the long-term outcomes and toxicities from a large cohort of patients with localized prostate cancer treated with low-dose-rate intraoperatively planned brachytherapy.

METHODS AND MATERIALS

Prostate-specific antigen levels, urinary symptoms, and erectile function were recorded at baseline, and each followup visit was then entered into a prospective database. Urinary toxicity requiring procedural intervention was retrospectively verified using an integrated electronic medical system. A separate cross-sectional survey was performed to measure postimplant sexual function.

RESULTS

A total of 822 patients with low and favorable intermediate-risk prostate cancer were treated at our institution between 2003 and 2013. The Kaplan-Meier estimates for biochemical recurrence for our cohort were 95% and 87% at 5 and 10 years, respectively. Cystoscopy, transurethral resection of prostate, or dilatation was required for 7.1% of 720 patients with more than 2 years of followup. At a median followup of 3.7 years, 64.4% of patients retained adequate erectile function for intercourse, with 54% of patients who were no longer sexually active postimplant reporting social factors as the primary reason.

CONCLUSIONS

Our institutional experience with intraoperative low-dose-rate prostate brachytherapy yielded excellent long-term results with a low incidence of urinary and sexual toxicity.

Implanted brachytherapy seed movement reflecting transrectal ultrasound probe-induced prostate deformation

PURPOSE

Compression of the prostate during transrectal ultrasound-guided permanent prostate brachytherapy is not accounted for during treatment planning. Dosimetry effects are expected to be small but have not been reported. The study aims to characterize the seed movement and prostate deformation due to probe pressure and to estimate the effects on dosimetry.

METHODS AND MATERIALS

C-arm fluoroscopy imaging was performed to reconstruct the implanted seed distributions (compressed and relaxed prostate) for 10 patients immediately after implantation. The compressed prostate was delineated on ultrasound and registered to the fluoroscopy-derived seed distribution via manual seed localization. Thin-plate spline mapping, generated with implanted seeds as control points, was used to characterize the deformation field and to infer the prostate contour in the absence of probe compression. Differences in TG-43 dosimetry for the compressed prostate and that on probe removal were calculated.

RESULTS

Systematic seed movement patterns were observed on probe removal. Elastic decompression was characterized by expansion in the anterior-posterior direction and contraction in the superior-inferior and lateral directions up to 4 mm. Bilateral shearing in the anterior direction was up to 6 mm, resulting in contraction of the 145 Gy prescription isodose line by 2 mm with potential consequences for the posterior-lateral margin. The average whole prostate D90 increased by 2% of prescription dose (6% max; p < 0.01).

CONCLUSIONS

The current investigation presents a novel study on ultrasound probe-induced deformation. Seed movements were characterized, and the associated dosimetry effects were nonnegligible, contrary to common expectation.

Intermittent androgen suppression for rising PSA level after radiotherapy

BACKGROUND

Intermittent androgen deprivation for prostate-specific antigen (PSA) elevation after radiotherapy may improve quality of life and delay hormone resistance. We assessed overall survival with intermittent versus continuous androgen deprivation in a noninferiority randomized trial.

METHODS

We enrolled patients with a PSA level greater than 3 ng per milliliter more than 1 year after primary or salvage radiotherapy for localized prostate cancer. Intermittent treatment was provided in 8-month cycles, with nontreatment periods determined according to the PSA level. The primary end point was overall survival. Secondary end points included quality of life, time to castration-resistant disease, and duration of nontreatment intervals.

RESULTS

Of 1386 enrolled patients, 690 were randomly assigned to intermittent therapy and 696 to continuous therapy. Median follow-up was 6.9 years. There were no significant between-group differences in adverse events. In the intermittent-therapy group, full testosterone recovery occurred in 35% of patients, and testosterone recovery to the trial-entry threshold occurred in 79%. Intermittent therapy provided potential benefits with respect to physical function, fatigue, urinary problems, hot flashes, libido, and erectile function. There were 268 deaths in the intermittent-therapy group and 256 in the continuous-therapy group. Median overall survival was 8.8 years in the intermittent-therapy group versus 9.1 years in the continuous-therapy group (hazard ratio for death, 1.02; 95% confidence interval, 0.86 to 1.21). The estimated 7-year cumulative rates of disease-related death were 18% and 15% in the two groups, respectively (P=0.24).

CONCLUSIONS

Intermittent androgen deprivation was noninferior to continuous therapy with respect to overall survival. Some quality-of-life factors improved with intermittent therapy. (Funded by the Canadian Cancer Society Research Institute and others; ClinicalTrials.gov number, NCT00003653.).

Optic glioma in children: surveillance, resection, or irradiation?

Eighty-seven consecutive children with newly diagnosed optic glioma were managed at University of Toronto hospitals 1958-1990. Overall the 10-year survival, relapse-free survival and freedom from second relapse rates were 84%, 68% and 85%. Twenty-seven patients relapsed or progressed, of whom 40% were free of a second relapse 10 years after the first relapse. Fourteen patients had a second relapse. Thirteen are dead. None survived 5 years after second relapse. Patients with anteriorly located tumors (N = 35), which involved the optic nerve, or chiasm and optic nerves, fared better than those with posteriorly located tumors (N = 52) with spread beyond the chiasm, 10-year survival 95% versus 76%, (p = .02), 10-year relapse-free survival 80% versus 59% (p = .02), respectively. For posterior tumors primary irradiation was more effective than primary subtotal resection for prevention of subsequent relapse, 10-year relapse-free survival 75% versus 41% (p = .02), but salvage therapy was, in part, successful and multivariate analysis of prognostic factors influencing survival for posterior tumors indicated that neither primary resection nor primary irradiation were significant factors. For first relapse, primary irradiation and the presence of neurofibromatosis were the significant favorable factors. Since 1977 and for posterior optic glioma subtotal resection or surveillance were used in 21/29 (72%) patients compared with 4/23 (17%) previously. Ten-year survival rates before and after 1977 were 78% and 67% and 10-year relapse-free survival 64% and 56%, respectively.