Impact of neoadjuvant hormonal therapy on dose-volume histograms in patients with localized prostate cancer under radical radiation therapy.

INTRODUCTION: Prostate volume involves a defined toxicity predictor in the radiation therapy of localized prostate cancer. Neoadjuvant hormone therapy (nHT) can reduce prostate volume and, therefore, the planned volume. The objective of this study was to establish if the value of nHT reduces the planned volume and if this reduction correlates with a reduction of the dose received in the target organs. MATERIAL AND METHODS: 28 patients diagnosed of localized prostate cancer and referred to our departments for radiation therapy with radical intention, in the period ranging between April 2002 and October 2003, were included prospectively. The patients received nHT (triptorelin + flutamide) for 2 months and adjuvant HT until completing 2 years in the high-risk cases. A transrectal ultrasound study was performed in all patients, simulation CT and planning before the start of HT and after 2 months of treatment. The radiation therapy was carried out with 6 or 18 MV LINAC photons, with a dose fractioning scheme of 5 x 180-200 cGy, a total dosage of 66-72 Gy to prostate, 56 Gy to seminal vesicles and, in the high-risk cases, 46 Gy to pelvic lymph nodes. RESULTS: The distribution according to risk group was: low risk 3.6%, intermediate risk 28.6% and high risk 67.9%. By transrectal ultrasound, prostate volume on diagnosis was 50.65 cc pre HT and 38.97 cc post HT (p < 0.001), which means a volume reduction of 24%. The comparative analysis of the dose-volume histograms of the first versus the second CT shows a reduction in the planned volume GTV1 (prostate) (81.33 cc vs 63.96 cc, p < 0.05), PTV1 (prostate and margin) (197.51 cc vs 168.38 cc, p < 0.001) and PTV2 (prostate, vesicles and margin) (340.5 cc vs 307.26 cc, p < 0.05), a reduction of the maximum dose in the seminal vesicles (70.2 versus 68.75 Gy, p < 0.05), a reduction of the mean dose in the seminal vesicles (65.07 Gy versus 63.07 Gy, p < 0.05), PTV2 (67.72 Gy versus 66.9 Gy, p < 0.01) and PTV3 (prostate, vesicles, pelvic lymph nodes and margin) (58.86 Gy versus 57.21 Gy, p < 0.01), a reduction of the D90 in the seminal vesicles (61.83 Gy versus 60.06 Gy, p < 0.05) and PTV2 (61.04 Gy versus 59.45 Gy, p < 0.05) and a reduction of V60 of the rectum (32.45% versus 28.22%, p < 0.05) and V60 of the bladder (41.78% versus 31.67%, p < 0.005). CONCLUSIONS: Neoadjuvant hormone therapy reduces significantly prostate volume and as a result the planned volume and consequently the rectal and bladder V60 can be significantly reduced.

Impact of neoadjuvant hormonal therapy on dose-volume histograms in patients with localized prostate cancer under radical radiation therapy

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Introduction. Prostate volume involves a definedtoxicity predictor in the radiation therapy of localizedprostate cancer. Neoadjuvant hormone therapy(nHT) can reduce prostate volume and, therefore,the planned volume. The objective of thisstudy was to establish if the value of nHT reducesthe planned volume and if this reduction correlateswith a reduction of the dose received in thetarget organs.Material and methods. 28 patients diagnosed of localizedprostate cancer and referred to our departmentsfor radiation therapy with radical intention,in the period ranging between April 2002 andOctober 2003, were included prospectively. The patientsreceived nHT (triptorelin + flutamide) for 2months and adjuvant HT until completing 2 yearsin the high-risk cases. A transrectal ultrasoundstudy was performed in all patients, simulation CTand planning before the start of HT and after 2months of treatment. The radiation therapy wascarried out with 6 or 18 MV LINAC photons, with adose fractioning scheme of 5 x 180-200 cGy, a totaldosage of 66-72 Gy to prostate, 56 Gy to seminalvesicles and, in the high-risk cases, 46 Gy to pelviclymph nodes.Results. The distribution according to risk groupwas: low risk 3.6%, intermediate risk 28.6% and highrisk 67.9%. By transrectal ultrasound, prostate volumeon diagnosis was 50.65 cc pre HT and 38.97 ccpost HT (p < 0.001), which means a volume reductionof 24%. The comparative analysis of the dosevolumehistograms of the first versus the second CTshows a reduction in the planned volume GTV1(prostate) (81.33 cc vs 63.96 cc, p < 0.05), PTV1(prostate and margin) (197.51 cc vs 168.38 cc, p <0.001) and PTV2 (prostate, vesicles and margin)(340.5 cc vs 307.26 cc, p < 0.05), a reduction of themaximum dose in the seminal vesicles (70.2 versus68.75 Gy, p < 0.05), a reduction of the mean dose inthe seminal vesicles (65.07 Gy versus 63.07 Gy, p <0.05), PTV2 (67.72 Gy versus 66.9 Gy, p < 0.01) andPTV3 (prostate, vesicles, pelvic lymph nodes andmargin) (58.86 Gy versus 57.21 Gy, p < 0.01), a reductionof the D90 in the seminal vesicles (61.83 Gyversus 60.06 Gy, p < 0.05) and PTV2 (61.04 Gy versus59.45 Gy, p < 0.05) and a reduction of V60 of the rectum(32.45% versus 28.22%, p < 0.05) and V60 of thebladder (41.78% versus 31.67%, p < 0.005).Conclusions. Neoadjuvant hormone therapy reducessignificantly prostate volume and as a resultthe planned volume and consequently the rectaland bladder V60 can be significantly reduced