QOL Comparison of Acute Side Effects From a High Dose Rate Vs. Low Dose Rate Prostate Brachytherapy Boost Combined With External Beam Radiotherapy

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To compare acute side-effects of patients undergoing a prostate brachytherapy boost combined with pelvic radiotherapy. From February 2012 to May 2014 all patients undergoing a combination of external beam pelvic radiotherapy (EBRT) and a prostate brachytherapy boost were approached for a prospective evaluation of acute toxicity and quality of life. All patients received 46 Gy in 23 fractions of EBRT using either a 3D conformal or IMRT technique. HDR brachytherapy preceded EBRT (either 15 Gy in one fraction or 20 Gy in 2 fractions) while LDR permanent seed implant using iodine-125 followed EBRT within 1-3 weeks. Patients may have been prescribed androgen deprivation therapy (ADT). Side effects were reported using the prostate cancer-specific HRQOL domains (urinary incontinence, urinary irritation/obstruction, sexual, bowel, and hormonal) of the EPIC questionnaire at baseline, 1 month and 3 or 4 months after completion of treatment, as well as physical and mental status using the SF-12 questionnaire. Additionally as per department standards all patients completed the International Prostate Symptom Score (IPSS). Patients had to be able to complete the health surveys in English. Two sample T-test was used to compare mean differences of month 0 and month 1 domain scores, mean differences of month 1 and month 4 domain scores and recovery of pre-treatment HRQOL scores after four months. 60 patients completed the required surveys (29 HDR and 31 LDR). Comparisons of the sexual and hormonal domains were not valid because of an imbalance in the use of ADT between the 2 groups (26/31 LDR and only 8/29 HDR). With p-values of 0.019, LDR patients were found to experience a significantly higher drop in urinary health after treatment. On average, bowel domain scores decreased by 20.1 points for the LDR group and 10.4 points for the HDR group. Four months after treatment, LDR patients continued to experience a significantly lower urinary health compared to HDR patients (p = 0.012). Urinary domain scores for the LDR group were on average 12.6 points lower compared to the pre-treatment assessment. In contrast, HDR patients almost regained pre-treatment urinary health standards with a mean difference of only 1.4. For the remaining domains, no significant difference in recovery between the two treatment groups could be found. This prospective non randomized comparison of acute toxicity and QOL after combined BT and EBRT suggests better tolerance of an HDR boost, whether a single 15 Gy or 2 × 10 Gy. A prospective randomized comparison is underway.