Fractionated perineal high-dose-rate temporary brachytherapy combined with external beam radiation in the treatment of localized prostate cancer: is lymph node sampling necessary?

PURPOSE: To study the influence of imaging based nodal staging and local dose escalation by a high-dose-rate brachytherapy (HDR-BT) boost in the treatment of locally confined prostate cancer in terms of prostate specific antigen (PSA) recurrence-free survival (biochemical non-evidence of disease (bNED)), treatment toxicity and prognostic variables.

PATIENTS AND METHODS: The prospectively recorded files of 144 men aged in a median of 68 years with a mean follow-up of 8 years (60-171 months) receiving curatively intended, transrectal ultrasound guided high-dose-rate 192-iridium-brachytherapy (HDR-BT) combined with external beam radiation therapy (EBRT) for locally confined prostate cancer were analyzed. T-stages were defined by digital rectal investigation and transrectal sonography (TRUS), nodal staging was performed with computed tomography(CT)/magnetic resonance imaging (MRI) (UICC/AJCR 1992). Twenty-nine patients (20.1%) had T1b-T2a tumors, and 115 patients had T2b-T3 tumors. Median initial PSA (iPSA) was 12.15 ng x mL(-1) (mean 25.61 ng x mL(-1)). The total planned dose applied by external beam radiation was 50 Gy in the pelvis, and 40 Gy in the prostate by in-field-dose modification by individual compensators. The perineal, TRUS guided HDR-BT was delivered in two fractions of 15 Gy each. The target of BT boost was the peripheral zone of the prostate.

RESULTS: The overall survival was 71.5% and that of the disease free survival 82.6%. Freedom from distant metastases in T3 stage was 91.3%, whereas for G3 lesions, it was 88.23%. The bNED rate was 72.9%. Regarding treatment related late toxicity according to the EORTC/RTOG score, we observed grade 1, 2, 3 proctitis in 9.72%, 6.94%, 4.10% as well as grade 1, 2, 3 cystitis in 12.5%, 4.16%, 2.08%, respectively. Grade 4 and 5 proctitis or cystitis were not registered.

CONCLUSION: The minimum 5-year and mean 8-year results confirm that local dose escalation by TRUS guided perineal HDR-BT and complementary external beam radiation of the pelvic lymphatics has curative potential in men with locally confined high-risk prostate cancer, although surgical staging results in the literature suggest a high probabilityof microscopic nodal involvements at the level of 25.61 ng x mL(-1) mean PSA. The influence of additional short-term (< 6 months) hormonal ablation on the treatment results could not be stated.