Long-Term Chronic Toxicity Of A Dose Escalating HDR-BT Boost Combined With Pelvic EBRT For Intermediate And High Risk Prostate Cancer

Main Category: Radiology / Nuclear Medicine
Also Included In: Prostate / Prostate Cancer;  Urology / Nephrology;  Cancer / Oncology
Article Date: 22 Sep 2008 - 3:00 PDT

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The results of conventional external-beam radiation therapy (EBRT) in intermediate/high-risk prostate cancer patients have been poor. Since a dose-response relationship has been established in these subgroups of patients, a dose-escalation trial using a combination of EBRT and high-dose-rate (HDR) brachytherapy boost (BT) was started at William Beaumont Hospital in 1991. An escalating dose regimen was used for the HDR boost component of the treatment. The concern with delivering high doses of radiation via HDR-BT was the risk of increasing chronic toxicity with the higher dose levels.

Using biological equivalent dose calculations and an alpha/beta of 1.5, we had three groups of patients ranging from less than 210 Gy (lowest-dose) to 275-306 Gy (highest dose). Chronic genitourinary and gastrointestinal (GU/GI) toxicities were graded using National Cancer Institute Common Toxicity Criteria version 3.0. The highest toxicity score encountered was used. Chronic GU/GI toxicity was analyzed using Pearson's Chi-square analysis and compared between the three dose levels, stratified as Grade 0, vs. Grade I/II, vs. Grade III. Chronic dysuria, frequency/urgency, retention, hematuria, urinary incontinence, urethral strictures, diarrhea, rectal bleeding, perineal pain/tenesmus, fistula and rectal ulcer were evaluated.

Although dysuria and hematuria grade I/II were higher in the high-dose group, grade IIIGU toxicities were very low in all patients, less than 3% despite over 50% more dose delivered. Likewise, GI toxicity was very low (< 0.5%) and not correlated with dose.

This study demonstrates that HDR-BT combined with EBRT is well tolerated and can safely be delivered without an increase in significant chronic toxicities. Therefore HDR-BT is an effective and safe dose-escalation method. The maximum biological equivalent dose (306Gy) delivered with this combined treatment approach is unmatched by any other radiation treatment methods.

Ghilezan Michael et al. William Beaumont Hospital, Royal Oak MI, USA

About ESTRO 27

ESTRO 27 (September 14th to 18th, 2008) offered an outstanding scientific programme combining lectures from eminent invited speakers, proffered papers and poster discussions, teaching lectures on a wide range of topics including clinical issues, brachytherapy, radiobiology, physics and technology as well as debates on controversial topics and clinical case discussions, a special poster reception, poster discussion sessions and electronic poster viewing.

ESTRO 27 hosted the largest European exhibition in Radiotherapy with participation from all the leading manufacturers.

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