Dose-Escalated Intensity Modulated Radiation Therapy for Prostate Cancer: 15-Year Outcomes Data

Abstract

Purpose To report 15-year outcomes for dose-escalated intensity modulated radiation therapy (IMRT) for localized prostate cancer (PC) by evaluating biochemical relapse, distant metastases, cancer-specific survival, and long-term toxicity. Methods and materials A database search was conducted for the first cohort of patients treated at this institution with 81 or 86.4 Gy between 1996 and 1998 using IMRT. Toxicity data were scored according to the Common Terminology Criteria for Adverse Events version 3.0. Median follow-up was 11.6 years (range, 5-21 years). Results In the study, 301 patients were treated with 81 Gy (n = 269, 89%) or 86.4 Gy (n = 32, 11%). Patients were analyzed by National Comprehensive Cancer Network risk group, with 29% low risk (LR), 49% intermediate risk (IR), and 22% high risk (HR). Late grade 3 gastrointestinal (GI) toxicity was seen in 3 patients (1.0%). No grade 4 GI toxicity events occurred. Median time from radiation therapy to late grade 3 GI toxicity was 2.9 years. One event occurred after 10 years. Late grade 3 and 4 genitourinary (GU) toxicity was seen in 6 (2.0%) and 1 (0.3%) patient, respectively. Median time to late grade 3+ GU toxicity was 5.5 years. Two events occurred after 10 years. In addition, 38 (12.6%) developed second primary malignancies (SPMs), 8 of which were in-field malignancies. Median time from radiation therapy to all SPM and in-field SPM was 10 years. The 15-year relapse-free survival was 76%, 65%, and 55% in the LR, IR, and HR groups, respectively. Distant metastases-free survival was 88%, 75%, and 63% for LR, IR, and HR patients, respectively. PC-specific mortality was 1.9%, 7.1%, and 12.2% for LR, IR, and HR patients. Conclusions This report represents the longest follow-up data set to our knowledge of patients treated with high-dose IMRT for PC. Our findings indicate that it is well tolerated with 1.0% and 2.3% incidence of long-term grade 3+ GI and GU toxicity, respectively. The cohort had excellent PC-specific survival.

Maintaining consistent bladder filling during external beam radiotherapy for prostate cancer

“…Standard fractionation EBRT for treatment of prostate cancer is delivered using daily radiation doses of 1.8-2 Gy, five days a week, over 8-10 weeks, up to a total dose of 86.4 Gy [7]. The radiobiologic characteristics of prostate cancer, which has low alpha/beta ratio, provided the theoretical basis for hypofractionated RT [8].…”

Impact of radiation dose on recurrence in high‐risk prostate cancer patients

“…We used the validated CPG 4 to discriminate between risk groups (Figure 1). With recurrence rates of 2.5%, 14.3%, 24.0%, and 40.5% for CPGs 2 to 5, respectively, this stratification tool identified a clear link between recurrence risk and pretreatment patient and tumor characteristics.…”

“…Radiation therapy (RT) combined with long‐term androgen deprivation therapy (ADT) is a standard of care option for men with high‐risk and locally advanced prostate cancer (PCa). Several studies have additionally demonstrated that dose escalation improves biochemical tumor control outcomes 1‐4 . However, higher doses of RT also results in increased rates of toxicity with five‐year late grade ≥2 gastrointestinal and genitourinary toxicity rates ranging from 12% to 15% 5 …”

Automatic localization of the prostatic urethra for image guided radiation therapy

“…Prostate cancer is the most prevalent non-cutaneous malignancy among men [1]. External Beam radiation therapy (EBRT) for prostate cancer using conventional fractionation provides 1.8-2 Gy per fraction every day, 5 days a week, over 7-10 weeks [2]. Image guided radiation therapy (IGRT) is usually utilized for EBRT as the prostate location can change relative to the pelvic bones, as a function of rectal and bladder filling.…”

“…Image guided radiation therapy (IGRT) is usually utilized for EBRT as the prostate location can change relative to the pelvic bones, as a function of rectal and bladder filling. Implantation of at least 3 fiducial markers in the prostate enables three dimensional localization of the prostate using daily 2D-kV or cone beam computerized tomography (CBCT) [2].…”