Abstract
PurposeEvaluation of clinical outcome of two-weekly high-dose-rate brachytherapy boost after external beam radiotherapy (EBRT) for localized prostate cancer.Methods338 patients with localized prostate cancer receiving definitive EBRT followed by a two-weekly high-dose-rate brachytherapy boost (HDR-BT boost) in the period of 2002 to 2019 were analyzed. EBRT, delivered in 46 Gy (DMean) in conventional fractionation, was followed by two fractions HDR-BT boost with 9 Gy (D90%) two and four weeks after EBRT. Androgen deprivation therapy (ADT) was added in 176 (52.1%) patients. Genitourinary (GU)/gastrointestinal (GI) toxicity was evaluated utilizing the Common Toxicity Criteria for Adverse Events (version 5.0) and biochemical failure was defined according to the Phoenix definition.ResultsMedian follow-up was 101.8 months. 15 (4.4%)/115 (34.0%)/208 (61.5%) patients had low-/intermediate-/high-risk cancer according to the D`Amico risk classification. Estimated 5-year and 10-year biochemical relapse-free survival (bRFS) was 84.7% and 75.9% for all patients. The estimated 5-year bRFS was 93.3%, 93.4% and 79.5% for low-, intermediate- and high-risk disease, respectively. The estimated 10-year freedom from distant metastasis (FFM) and overall survival (OS) rates were 86.5% and 70.0%. Cumulative 5-year late GU toxicity and late GI toxicity grade ≥ 2 was observed in 19.3% and 5.0% of the patients, respectively. Cumulative 5-year late grade 3 GU/GI toxicity occurred in 3.6%/0.3%.ConclusionsTwo-weekly HDR-BT boost after EBRT for localized prostate cancer showed an excellent toxicity profile with low GU/GI toxicity rates and effective long-term biochemical control.
Highlights
Prostate cancer represents the most common cancer type among adult men [1]
Cumulative 5-year late GU toxicity and late GI toxicity grade ≥ 2 was observed in 19.3% and 5.0% of the patients, respectively
Cumulative 5-year late grade 3 GU/GI toxicity occurred in 3.6%/0.3%
Summary
Prostate cancer represents the most common cancer type among adult men [1]. Curative radiotherapy in localized disease is well established. Due to a low a/b - ratio of prostate cancer and subsequent high sensitivity to dose fractionation, hypofractionated and dose-escalated therapy regimes show an improved therapeutic ratio in the treatment of prostate cancer [2,3,4,5]. Keeping the limits of normal tissue tolerance for organs at risk remains difficult in dose-escalated external beam radiation therapy (EBRT). High-dose-rate brachytherapy (HDR-BT) is able to deliver high single doses while respecting the dose constraints of the surrounding organs at risk. HDR-BT is not quite as affected by the movement of organs at risk caused by organ filling compared to EBRT and offers excellent dose conformity. There is concern that periprostatic disease, especially in high-risk cancer, is not treated sufficiently by HDRBT alone. To obtain the advantages of both therapies, EBRT is often combined with a HDR-BT boost and randomized data has shown the superiority of the combination therapy over EBRT alone [6, 7]
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