Clinical factors and dosimetry associated with the development of prostate brachytherapy–related urethral strictures: A matched case–control study

A Population-based Statistical Model for Investigating Heterogeneous Intraprostatic Sensitivity to Radiation Toxicity After 125I Seed Implantation

AIM

To develop a population-based statistical model in order to find a spatial pattern of dose distribution which is related to lower urinary tract symptoms (LUTS) after iodine-125 (¹²⁵I) seed implantation for prostate cancer.

PATIENTS AND METHODS

A total of 75 patients underwent ¹²⁵I seed implantation for prostate cancer. Principal component analysis was applied to the standardized dose array and for each patient dose distribution was uniquely characterized by a combination of weighted eigenvectors. The correlation between eigenvectors and the severity of LUTS was investigated with linear regression analysis.

RESULTS

Eight eigenvectors were identified as being significantly associated with the severity of LUTS (p<0.05). Multivariate regression model identified that intraprostatic parameters, which were positively associated with the severity of LUTS, were distributed around a portion of the urethral base and a peripheral region of the prostate.

CONCLUSION

We established a population-based statistical model that may indicate a significant dose pattern associated with the severity of radiation toxicity.

Late toxicity after single dose HDR prostate brachytherapy and EBRT for localized prostate cancer: Clinical and dosimetric predictors in a prospective cohort study

PURPOSE

To describe the genitourinary (GU) and gastrointestinal (GI) late toxicity profile and to analyse the clinical and dosimetry outcomes predictors of the combination of EBRT and high-dose-rate (HDR) prostate brachytherapy (BT) for localized prostate cancer.

MATERIALS AND METHODS

Between January 2012 and May 2017, 210 patients were included in a prospective protocol. Treatment consisted in HDR-BT (15 Gy single fraction) plus 3DCRT (37.5 Gy/15 fractions). Univariate and multivariate logistic regressions were used to analyse the impact of variables on late toxicity.

RESULTS

Median age was 71 (56-82), 12.4% of patients had low, 44.3% intermediate and 41% high-risk prostate cancer. Median prostate volume was 28.4 cc. Median V100, V150, V200 were 98.2%, 27% and 7.4% respectively. Median urethra Dmax, rectum D1cc and D2cc, were 113.5%, 62.2%% and 54.2% respectively. After a median follow-up of 41 months (5-75) late G2 GU and GI late toxicity was observed in 14.8% and 5.2% of patients respectively. Late G3 GU and GI toxicity occurred in 0% and 1% of patients respectively. There were no outcome correlations with late G ≥ 2 GU toxicity on univariate analysis. Previous cardiovascular comorbidity (p = 0.042), and dose to the rectum D2cc (p = 0.016) and D1cc (p = 0.017) were associated with G ≥ 2 GI toxicity. Multivariate analysis showed that rectum D1cc (HR11.56; 95%CI 1.4-92.1; p = 0.021) and prior history of cardiovascular disease (HR3.6; 95%CI 1-12.9; p = 0.045) remained independent predictors of G ≥ 2 GI toxicity.

CONCLUSIONS

There is a low incidence of late GU and GI morbidity using single fraction HDR-BT and hypofractionated EBRT. Previous cardiovascular disease and dose to the rectum were observed to correlate with GI toxicity.

Posterior urethral stenosis after prostate cancer treatment: contemporary options for definitive management

Posterior urethral stenosis (PUS) is an uncommon but challenging problem following prostate cancer therapy. A review of the recent literature on the prevalence of PUS and treatment modalities used in the last decade was performed. A summative narrative of current accepted techniques in management of PUS is presented, and supplement with our own experience and algorithms.

Reductions in prostatic doses are associated with less acute morbidity in patients undergoing Pd-103 brachytherapy: Substantiation of the rationale for focal therapy

PURPOSE

Interest in prostate dose reduction or focal treatment exists due to expected reductions in treatment morbidity. Prior analyses have not generally corroborated relationships between prostate or urethral dose and urinary toxicity after brachytherapy, but such analyses have been performed on cohorts all receiving the same prescribed dose. We analyzed patients treated to differing prescription doses to assess acute urinary morbidity with dose reduction.

METHODS AND MATERIALS

Patients treated with Pd-103 to either 125 Gy or 90-100 Gy were compared using the International Prostate Symptom Score (IPSS) at 1-month postimplant. Patients in the 90-100 Gy cohort began external beam radiation therapy after their 1-month assessment; thus, toxicities were measured before contribution from external beam radiation therapy. Patient/treatment characteristics were compared to verify subgroup homogeneity. Dose and change in IPSS 1 month after treatment were assessed using a multivariate linear regression model.

RESULTS

One hundred ninety-one and 41 patients were treated with 125 Gy versus 90-100 Gy, respectively. Preimplant and postimplant prostate volumes and initial IPSS were similar between groups. Higher prescription dose and increased pretreatment IPSS were independent predictors of increased 1-month IPSS. In addition, every 10 percentage point additional prostate volume receiving a given dose was associated with increase in IPSS after treatment for the same level of pretreatment IPSS.

CONCLUSION

Lower prescription dose and decreased volume of high-dose regions to the prostate correlated with reduced acute urinary morbidity after brachytherapy. Our findings suggest that focal treatment approaches with modest dose reductions to subregions of the prostate may reduce acute morbidity and potentially expand the number of patients eligible for brachytherapy.