Proposal for a predictive model of erectile function after permanent 125I prostate brachytherapy for localized prostate cancer

Biochemical outcomes and toxicities in young men with prostate cancer after permanent iodine-125 seed implantation: Prospective cohort study in 6662 patients

PURPOSE

We evaluated the effect of age, <60 and ≥60 years, on biochemical outcomes and toxicities in patients with prostate cancer who underwent permanent seed implantation (PI) ± external beam radiation therapy ± hormone therapy in a national Japanese prospective cohort study (J-POPS).

METHODS AND MATERIALS

The safety and efficacy analyses included 6721 and 6662 patients, respectively. We categorized patients into two age groups: <60 (n = 716) and ≥60 (n = 6,005) years. We used propensity score matching (PSM) to estimate the marginal effect of age on biochemical freedom from failure (bFFF) using a Phoenix definition and Cox proportional hazard models.

RESULTS

The median followup period was 60.0 months. Without PSM, men <60 years demonstrated similar 5-year bFFF (96.3%) compared with men ≥60 years (95.6%; p = 0.576); percent positive biopsies, biologically effective dose, Gleason score, risk classification, and supplemental external beam radiation therapy (p <0.001, <0.001, <0.001, 0.008, and <0.001) were significantly associated with bFFF while age was not (p = 0.576). With PSM, bFFF was not significantly different between age groups (p = 0.664); however, men <60 years showed a significantly lower incidence of declining erectile function, grade ≥2 all urinary toxicities, urinary frequency/urgency, and rectal bleeding (p <0.001, 0.024, 0.031, and 0.010) than men ≥60 years.

CONCLUSIONS

After PI, men <60 years achieved a comparable 5-year biochemical control rate and showed a lower incidence of several toxicities compared to men ≥60 years. This suggests that PI should be an excellent treatment option for men <60 years with prostate cancer.

Evaluation of erectile potency and radiation dose to the penile bulb using image guided radiotherapy in the CHHiP trial

BACKGROUND AND PURPOSE

The penile bulb (PB) dose may be critical in development of post prostate radiotherapy erectile dysfunction (ED). This study aimed to generate PB dose constraints based on dose-volume histograms (DVHs) in patients treated with prostate radiotherapy, and to identify clinical and dosimetric parameters that predict the risk of ED post prostate radiotherapy.

MATERIALS AND METHODS

Penile bulb DVHs were generated for 276 patients treated within the randomised IGRT substudy of the multicentre randomised trial, CHHiP. Incidence of ED in relation to dose and randomised IGRT groups were evaluated using Wilcoxon rank sum, Chi-squared test and atlases of complication incidence. Youden index was used to find dose-volume constraints that discriminated for ED. Multivariate analysis (MVA) of effect of dosimetry, clinical and patient-related variables was performed.

RESULTS

Reduced treatment margins using IGRT (IGRT-R) produced significantly reduced mean PB dose compared with standard margins (IGRT-S) (median: 25 Gy (IGRT-S) versus 11 Gy (IGRT-R); p < 0.0001). Significant difference in both mean (median: 23 Gy (ED) vs. 18 Gy (no ED); p = 0.011) and maximum (median: 59 Gy (ED) vs. 52 Gy (no ED); p = 0.018) PB doses between those with and without clinician reported ED were identified. Mean PB dose cut-point for ED was derived at around 20 Gy. On MVA, PB mean dose and age predicted for impotence.

CONCLUSION

PB dose appears predictive of post-radiotherapy ED with calculated threshold mean dose of around 20 Gy, substantially lower than published recommendations. IGRT-R enables favourable PB dosimetry and can be recommended provided prostate coverage is not compromised.

Association between long-term erectile dysfunction and biochemical recurrence after permanent seed I(125) implant brachytherapy for prostate cancer. A longitudinal study of a single-institution

We aimed to investigate the predictive factor of erectile dysfunction (ED) in prostate cancer (PCa) patients who underwent low-dose permanent I(125) seed implant brachytherapy and to investigate if ED could represent a patient's reported outcome measures (PROMs) of efficacy of BT and indirectly associated with biochemical recurrence free survival (BRFS). From 2000 to 2012, 176 consecutive patients with low-risk PCa underwent BT. ED was evaluated with the International Index of Erectile Function (IIEF-5). Cox regression analysis was performed to assess significant predictors of mild-to-severe ED and BRFS after BT, including covariates. The 10-year actuarial rate of ED was 66%. Subjects with severe ED had higher values of D90 (183.0 versus 177.0; p < 0.05) and V100% (40.1 versus 31.4; p < 0.05) compared with normal. At the multivariate logistic regression analysis, D90 (OR: 1.10; p < 0.05) was an independent predictor of ED. Multivariate Cox-regression analysis did not demonstrate significant association between erectile preservation and biochemical recurrence (BCR) after 10 years of follow up (HR: 2.15; p = 0.20), while D90 ≤ 180 Gy independently predicted BCR (HR: 4.65; [95%CI: 1.25-17.34]; p < 0.05). Erectile preservation should be addressed as valuable PROMs after permanent seed I(125) implant, but it is not associated with better BRFS.

[Erectile dysfunction evaluation after brachytherapy for low risk prostate adenocarcinoma: prospective study of patients with a baseline IIEF5>16]

PURPOSE

To evaluate erectile function (EF) prospectively from 1 to 2 years post-brachytherapy in patients with a baseline IIEF5 score>16.

METHODS

Between 2007 and 2012, 179 patients underwent an exclusive brachytherapy for localised low risk prostate adenocarcinoma. Neo-adjuvant hormotherapy (15.6%) and post-brachytherapy intake phosphodiesterase inhibitors (PDE5i) were not considered as exclusion criteria. EF was evaluated via a scoring questionnaire IIEF5 before the surgical implantation, at month 12 and 24 post-operation. Only patients with an initial IIEF5 score>16 were included.

RESULTS

Of the 179 patients, 102 (57%) had a baseline IIEF5>16. At 12 months, 51.1% maintained an IIEF5>16 and 24.5% had a mild to moderate erectile dysfunction (ED), so that a total of 75.6% with IIEF5≥12. About 18% of patients had used PDE5i. At 24 months, 53.2% had an IIEF5>16 and 80.6% had an IIEF5≥12. Severe ED was reported in only 14.5% of the patients. The mean IIEF5 was 16.2 with an average decline of 5 points from the initial stage. All patients who were treated with PDE5i (27%) could have sexual intercourse. EF at baseline was reported as the only predictive factor of ED in multivariate analysis, 70% of patient without ED initially, had an IIEF5>16 at 1 and 2 years.

CONCLUSION

Severe ED was quite rare (14%) during the first 2 years post-brachytherapy and more than half of patients maintained an IIEF5>16. The main predictive factor was the erectile function at baseline.

LEVEL OF EVIDENCE

4.