Recently, HDR brachytherapy delivering only a 19 Gy fraction was proposed as exclusive treatment for low and intermediate risk prostate cancers. With a median 3-year follow-up, the Spanish team reported a biochemical control rate of 100% and 87%, respectively, for low risk and intermediate risk tumors. In parallel with these encouraging results regarding biochemical control, the authors described excellent urinary and digestive tolerance, notably the absence of grade > 2 complications. However, it should be noted, in this study, that special protection was provided to the anterior aspect of the rectum by means of a 10 ml transperineal injection of hyaluronic acid into the prostate-rectal interspace.

The idea of using a single high dose (in one fraction) was proposed at the MSKCC by the team of Fucks et al. which, in 2008, following a median 18-month follow-up, published a a 90% local control rate for spinal metastases after a single dose at 18 to 24 Gy.

The aim of the present study is to analyze acute urinary and digestive toxicity (< 180 days) observed following interstitial high dose rate prostate brachytherapy delivering a total dose of 20 Gy in one fraction.

Expected benefit(s) of the trial

• Improved quality of life during brachytherapy on account of the absence of radioactive seeds in the prostate:

  • Fewer early urinary complications,
  • No urine filtration,
  • No post-operative use of condoms,
  • No 2-year ban on cremation following treatment,

• Health cost savings,

• Acquisition of dosimetric data for inverse optimization.

Predictable risk(s) for patients Predictable risks in the context of this trial involve the frequency of essentially urinary disorders.

Methodology Open, monocentric, phase I-II study.

Inclusion Criteria:

• Patients suffering from histologically-proven adenocarcinoma-type prostate cancer:

  • with low risk of biochemical recurrence
  • with a low intermediate risk of biochemical recurrence (maximum of 1 intermediate risk factor)*
  • stage T1c, T2a, T2b
  • Gleason score 6 (3+3) or 7 (3+4) with at most 3 positive biopsies

• PSA < 15 ng/ml

• Age ≥ 18 years

• Karnofsky index ≥ 70%

• Life expectancy ≥ 10 years

• No contraindication to injection of hyaluronic acid in the prostate-rectal interspace

• Patient aware of the information leaflet and having signed the informed consent form

• Patient covered by medical insurance

Exclusion Criteria:

• Stage ≥ T2c

• Gleason score 7 (4+3) or ≥ 8

• PSA > 15 ng/ml

• Presence of the following anatomico-pathological criteria:

  • Involvement of the nerve fibers
  • Peri-tumoral vascular embolisms
  • Capsule involvement
  • Number of positive biopsies ≥ 50%
  • 100% positive biopsies in a lobe
  • Involvement of the seminal vesicle

• Prostate volume ≥60 cc

• Large prostatic transurethral resection and/or dating from less than 6 months

• Poor urinary function in the absence of alpha-blockers

  • IPSS score > 15
  • Post-mictional residue > 50 cc
  • Flow rate with Qmax < 12 ml/s

• Remote metastasis

• Neoadjuvant anti-androgenic treatment

• Prior treatment with pelvic irradiation and/or chemotherapy

• Active infection or other underlying severe pathology likely to prevent the patient from receiving treatment

• History of cancer other than basocellular cutaneous cancer or other form of cancer in complete remission for more than 5 years

• Evolving psychiatric disorder

• Vulnerable persons as defined by article L1121-5 to -8