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Prognostic factors for maintained efficacy of Sildenafil citrate in the management of erectile dysfunction after radiotherapy for prostate cancer
S274
I. J. Radiation Oncology
1021
● Biology ● Physics
Volume 57, Number 2, Supplement, 2003
Prognostic Factors for Maintained Efficacy of Sildenafil Citrate in the Management of Erectile Dysfunction after Radiotherapy for Prostate Cancer
D. D’Ambrosio, M. Zelefsky, H. Chan, Z. Fuks, S. Leibel Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY Purpose/Objective: We have previously reported the efficacy of Sildenafil citrate (SC) for erectile dysfunction (ED) after radiotherapy for prostate cancer. Yet there is scant information concerning the durability of efficacy of this medication for ED and the prevalence of continued usage and satisfaction among patients who use the medication. We report here the long-term efficacy of SC for ED after 3-dimensional conformal radiotherapy (3D-CRT) and brachytherapy. Materials/Methods: Between 1998 and 2002, three-hundred and sixty three (363) patients with clinically localized prostate cancer were treated with 3D-CRT (median dose 81 Gy) or permanent interstitial seed implantation and were prescribed SC for ED. All patients were potent prior to therapy, experienced some degree of ED after treatment, and were prescribed SC (50 –100mg). The clinical efficacy of SC was assessed at each follow up visit and the degree of ED was graded as being completely impotent, partially potent but unable to penetrate, or potent sufficient for penetration. The following variables were also evaluated to assess predictors for an effective outcome with SC: usage of SC prior to radiation therapy, mode of radiation therapy (brachytherapy vs 3D-CRT), prescribed radiation dose, patient age, diabetes status, and the use of neoadjuvant hormonal therapy. Results: Overall, SC was effective in 75% of patients upon initial trial, SC continued to be routinely used and maintained its efficacy in 96% of these patients. Only 6 (2%) patients in whom SC was effective at initial usage found the medication to be less effective with time and discontinued its usage. The median time of usage of SC in these patients was 3.7 years (range 4 – 45 months). Higher external beam radiation doses were associated with decreased efficacy of SC. Among patients who received 75.6 Gy or higher, the efficacy of SC was 72% compared to 85% for patients who received lower doses (p⫽.0001). These differences were not observed for the various dose levels among those treated with brachytherapy. The administration of hormonal therapy, diabetes and patient age and mode of radiotherapy had no significant impact on the efficacy of SC in this patient population. Conclusions: Our results confirm that SC can effectively be used to improve ED after treatment of prostate cancer with either 3D-CRT or interstitial brachytherapy. Higher dose levels of EBRT were identified as a negative prognostic factor for response to SC. The low discontinuation rate of SC over time is an indication of patient satisfaction in maintaining erectile function after treatment for prostate carcinoma.
1022
Radiation Dose Delivered to the Proximal Penis as a Predictor of the Risk of Erectile Dysfunction after Three-dimensional Conformal Radiotherapy for Localized Prostate Cancer
A.G. Wernicke, E. Pequignot, K. DiEva, C. Houser, R.K. Valicenti Radiation Oncology, Thomas Jefferson University Hospital, Philadelphia, PA Purpose/Objective: Recent studies have suggested a correlation between proximal penis irradiation and postradiation impotence in prostate cancer patients. In this study, we evaluated whether radiation dose to the bulb of the penis is predictive of erectile dysfunction (ED), and we investigated associations of three-dimensional conformal radiation therapy (3D CRT)induced ED, ejaculatory difficulty (EJD), and overall satisfaction with sex life (QOL). Materials/Methods: Fifty-six consecutive patients with AJCC stage II prostate cancer, mean PSA was 7.0 ng/ml (range, 2.9 – 18.5 ng/ml), treated with radiation alone to a median dose 73.8Gy (range, 66.6 – 79.2 Gy), reporting sexual potency (ED⫽0%) prior to 3D CRT, were evaluated by determining the doses received by the penile bulb and a validated self-administered sexual function survey before and after treatment. Follow up information on the patients initiated on Viagra was excluded from the analysis. ED was defined as the inability to have an erection firm enough to initiate intercourse. ED firmness score ranged from “not at all” (0), “low” (1), “medium” (2), “medium high” (3), and “high” (4). EJD score ranged from “no sexual stimulation” (0), “a lot of difficulty” (1), “some difficulty” (2), “little difficulty” (3), and “no difficulty” (4). QOL score ranged from “very dissatisfied” (0), “mostly dissatisfied” (1), “neutral or mixed” (2), “mostly satisfied” (3), and “very satisfied” (4). The bulb of the penis was outlined, and the dose volume histograms (DVH) were obtained on each patient. The radiation dose distribution to the bulb of the penis was defined as percentages —15%, 30%, 45%, 60%, 75%, and 90% — of the bulb (D15, D30, D45, D60, D75, D90). Fisher’s exact test and Wilcoxon test were used to evaluate the risk of ED, EJD and QOL and reduction in mean scores from baseline. Results: The median follow-up time was 23 months (range, 4 – 61 months). Two factors suggestive of predicting ED at 2 years after 3D CRT were 60% (D60) of the penile bulb volume receiving ⱖ 45Gy and 30% (D30) getting ⱖ 65Gy. A strong correlation was identified when assessing mean EJD scores at D60 and D30 of penile bulb receiving ⱖ 45Gy (p⫽0.026) and ⱖ 65Gy, respectively (p⫽0.043). The results are summarized in the table. Conclusions: To date, this is the first analysis assessing sexual QOL of patients with localized prostate cancer with respect to the irradiation of the penile bulb. We found a strong correlation between D60 and D30 of penile bulb receiving ⱖ 45Gy and ⱖ 65Gy, respectively, and a decrease of EJD scores from baseline at 2 years following the end of radiotherapy. An expanded study is underway to better establish penile bulb DVH parameters to direct inverse treatment planning for prostate cancer radiation therapy. This study may guide radiation oncologists to consider the doses and percentages, which are being delivered to the penile bulb in men treated for prostate cancer in order to preserve sexual potency.
I. J. Radiation Oncology
1021
● Biology ● Physics
Volume 57, Number 2, Supplement, 2003
Prognostic Factors for Maintained Efficacy of Sildenafil Citrate in the Management of Erectile Dysfunction after Radiotherapy for Prostate Cancer
D. D’Ambrosio, M. Zelefsky, H. Chan, Z. Fuks, S. Leibel Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY Purpose/Objective: We have previously reported the efficacy of Sildenafil citrate (SC) for erectile dysfunction (ED) after radiotherapy for prostate cancer. Yet there is scant information concerning the durability of efficacy of this medication for ED and the prevalence of continued usage and satisfaction among patients who use the medication. We report here the long-term efficacy of SC for ED after 3-dimensional conformal radiotherapy (3D-CRT) and brachytherapy. Materials/Methods: Between 1998 and 2002, three-hundred and sixty three (363) patients with clinically localized prostate cancer were treated with 3D-CRT (median dose 81 Gy) or permanent interstitial seed implantation and were prescribed SC for ED. All patients were potent prior to therapy, experienced some degree of ED after treatment, and were prescribed SC (50 –100mg). The clinical efficacy of SC was assessed at each follow up visit and the degree of ED was graded as being completely impotent, partially potent but unable to penetrate, or potent sufficient for penetration. The following variables were also evaluated to assess predictors for an effective outcome with SC: usage of SC prior to radiation therapy, mode of radiation therapy (brachytherapy vs 3D-CRT), prescribed radiation dose, patient age, diabetes status, and the use of neoadjuvant hormonal therapy. Results: Overall, SC was effective in 75% of patients upon initial trial, SC continued to be routinely used and maintained its efficacy in 96% of these patients. Only 6 (2%) patients in whom SC was effective at initial usage found the medication to be less effective with time and discontinued its usage. The median time of usage of SC in these patients was 3.7 years (range 4 – 45 months). Higher external beam radiation doses were associated with decreased efficacy of SC. Among patients who received 75.6 Gy or higher, the efficacy of SC was 72% compared to 85% for patients who received lower doses (p⫽.0001). These differences were not observed for the various dose levels among those treated with brachytherapy. The administration of hormonal therapy, diabetes and patient age and mode of radiotherapy had no significant impact on the efficacy of SC in this patient population. Conclusions: Our results confirm that SC can effectively be used to improve ED after treatment of prostate cancer with either 3D-CRT or interstitial brachytherapy. Higher dose levels of EBRT were identified as a negative prognostic factor for response to SC. The low discontinuation rate of SC over time is an indication of patient satisfaction in maintaining erectile function after treatment for prostate carcinoma.
1022
Radiation Dose Delivered to the Proximal Penis as a Predictor of the Risk of Erectile Dysfunction after Three-dimensional Conformal Radiotherapy for Localized Prostate Cancer
A.G. Wernicke, E. Pequignot, K. DiEva, C. Houser, R.K. Valicenti Radiation Oncology, Thomas Jefferson University Hospital, Philadelphia, PA Purpose/Objective: Recent studies have suggested a correlation between proximal penis irradiation and postradiation impotence in prostate cancer patients. In this study, we evaluated whether radiation dose to the bulb of the penis is predictive of erectile dysfunction (ED), and we investigated associations of three-dimensional conformal radiation therapy (3D CRT)induced ED, ejaculatory difficulty (EJD), and overall satisfaction with sex life (QOL). Materials/Methods: Fifty-six consecutive patients with AJCC stage II prostate cancer, mean PSA was 7.0 ng/ml (range, 2.9 – 18.5 ng/ml), treated with radiation alone to a median dose 73.8Gy (range, 66.6 – 79.2 Gy), reporting sexual potency (ED⫽0%) prior to 3D CRT, were evaluated by determining the doses received by the penile bulb and a validated self-administered sexual function survey before and after treatment. Follow up information on the patients initiated on Viagra was excluded from the analysis. ED was defined as the inability to have an erection firm enough to initiate intercourse. ED firmness score ranged from “not at all” (0), “low” (1), “medium” (2), “medium high” (3), and “high” (4). EJD score ranged from “no sexual stimulation” (0), “a lot of difficulty” (1), “some difficulty” (2), “little difficulty” (3), and “no difficulty” (4). QOL score ranged from “very dissatisfied” (0), “mostly dissatisfied” (1), “neutral or mixed” (2), “mostly satisfied” (3), and “very satisfied” (4). The bulb of the penis was outlined, and the dose volume histograms (DVH) were obtained on each patient. The radiation dose distribution to the bulb of the penis was defined as percentages —15%, 30%, 45%, 60%, 75%, and 90% — of the bulb (D15, D30, D45, D60, D75, D90). Fisher’s exact test and Wilcoxon test were used to evaluate the risk of ED, EJD and QOL and reduction in mean scores from baseline. Results: The median follow-up time was 23 months (range, 4 – 61 months). Two factors suggestive of predicting ED at 2 years after 3D CRT were 60% (D60) of the penile bulb volume receiving ⱖ 45Gy and 30% (D30) getting ⱖ 65Gy. A strong correlation was identified when assessing mean EJD scores at D60 and D30 of penile bulb receiving ⱖ 45Gy (p⫽0.026) and ⱖ 65Gy, respectively (p⫽0.043). The results are summarized in the table. Conclusions: To date, this is the first analysis assessing sexual QOL of patients with localized prostate cancer with respect to the irradiation of the penile bulb. We found a strong correlation between D60 and D30 of penile bulb receiving ⱖ 45Gy and ⱖ 65Gy, respectively, and a decrease of EJD scores from baseline at 2 years following the end of radiotherapy. An expanded study is underway to better establish penile bulb DVH parameters to direct inverse treatment planning for prostate cancer radiation therapy. This study may guide radiation oncologists to consider the doses and percentages, which are being delivered to the penile bulb in men treated for prostate cancer in order to preserve sexual potency.