Abstract

María Cerrolaza¹, Agustina Mendez², Maria del Mar Puertas², Cristina García², Sonia Flamarique², Cecilia Escuin¹, Victoria Navarro¹, Alberto Lanuza², David Villa³, Blanca Garcia², Martin Tejedor²

¹University Hospital Miguel Servet, Radiation Oncology, Zaragoza, Spain; ²University Hospital Miguel Servet , Radiation Oncology, Zaragoza, Spain; ³University Hospital Miguel Servet , Medical Physics, Zaragoza, Spain

Localized Prostate cancer has multiple therapeutic options including radical prostatectomy, brachytherapy and external beam radiation therapy. In our center the radiotherapy techniques used for this type of cancer are LDR-brachytherapy (BQT) and stereotactic body radiation therapy (SBRT).

Our objective is to identify and compare the oncologic results, toxicities, and PSA response in the treatment of localized prostate cancer by LDR brachytherapy and SBRT.

Data were retrospectively collected for all patients diagnosed with low or intermediate-risk prostate cancer treated with LDR brachytherapy or SBRT from 2015 to 2016. BQT was performed by transperineal insertion of permanent seeds of Iodine 125. The prescribed dose of SBRT was 35 Gy in 5 fractions of 7 Gy once a week. Oncologic characteristics and follow-up were evaluated every 6 months including PSA, toxicities (CTCAE V5) and recurrences. A comparative analysis was performed using chi-square and T student. A p-value less than 0.05 was statistically significant.

146 patients were analyzed, 66 treated with BQT (45%) and 80 SBRT (55%). The mean age was 67.8 in the BQT group and 70.26 in the SBRT group (p=0.036) with a PSA at diagnosis of 7.31 in the BQT group and 9.055 in the SBRT group (p=0.004). The most common Gleason grade in both groups was 6, 85% in BQT and 60% SBRT (p=0.001). The most frequent stage was T1c, 97% treated with BQT and 75% with SBRT (p=0.002).

Prior to radiotherapy treatment, 17% of patients who underwent BQT and 44% SBRT, received hormone blockade (CAB) (p= 0.001). 

Differences were observed in acute intestinal toxicity with greater toxicity in those treated with SBRT. When evaluating chronic toxicity, differences were observed in greater urinary toxicity in patients treated with BQT and greater intestinal toxicity in patients treated with SBRT. Throughout follow-up 17 patients (25.75%) presented grade 3 toxicity with BQT and 5 patients treated with SBRT (6.25%).

PSA follow-up was studied in subjects who had not previously received CAB. They presented differences in the Nadir value between both groups reached, 0.227 with BQT and 0.618 with SBRT (p= 0.006) as well as the percentage of PSA decrease respect to diagnosis, -97.27% BQT and -92.25% SBRT (p=0. 001). The time of reaching nadir PSA, 85.45% of patients treated with BQT reached PSA after 2.5 years of follow-up and 57.78% of those treated with SBRT (p=0.004).

Differences were only found in the proportion of PSA decline follow-ups between 30 months and 4 years.

With a median follow-up of 61.16 months 6 patients presented recurrences, 3 from each group (p=0.8) and 16 patients died due to other causes.

LDR brachytherapy and SBRT are two equally effective therapies in the treatment of low and intermediate-risk prostate cancer, with differences in toxicity profile and PSA response during follow-up.