Feasibility of MRI guided focal high-dose-rate brachytherapy for localized prostate cancer (Plaatselijke inwendige bestraling voor patiënten met prostaatkanker).

Favourable risk prostate cancer is common in men in developed countries. These cancers are often biologically indolent and therefore not clinically significant. However, no consensus has been reached with regard to the best approach of these tumours. Nowadays, low-dose-rate (LDR) brachytherapy is often implemented for patients with favourable risk prostate cancer, since it is a minimally invasive procedure. Still, grade 3 toxicity remains a concern in 5-34% of all series. Studies regarding high-dose-rate (HDR) brachytherapy (BT) as monotherapeutic treatment of the entire prostate, show promising results regarding toxicity of bladder and rectum. Nevertheless, severe toxicity is still present. To reduce toxicity in patients with localized prostate cancer, focal treatment is warranted. This can be achieved with MRI guided high-dose-rate brachytherapy. In the past, focal treatment has not been explored since determination of exact tumour location was not precise. Currently, our radiotherapy centre is the only department worldwide with an MRI HDR brachytherapy facility, allowing MRI guided catheter placement and treatment. With this facility, catheter placement can be done far more accurately, which makes focal treatment possible. By using focal treatment, less toxicity is expected. In earlier studies, a dose of 19 Gy to the entire prostate was shown to be adequate. Therefore we believe that focal treatment of 19 Gy to the tumour focus will be of benefit to the patient with localized prostate cancer. In case of recurrent (biochemical) disease, suitable re-treatment will be performed.

Country of recruitment: The Netherlands.

To reduce treatment-related toxicity in patients with localized prostate cancer, focal treatment is warranted. This can be achieved with MRI guided high-dose-rate brachytherapy. We expect that a single dose of 19 Gy to the tumour volume will be of benefit to the patient with localized prostate cancer.

The treatment includes one high-dose-rate brachytherapy procedure, administering 19 Gy in a single session.
Questionnaires will be used to assess toxicity and quality of life (before treatment, one month after treatment, every 3 months the first year, every 6 months the second year, thereafter once a year for up to 10 years). For assessment of biochemical recurrence, PSA monitoring will be performed during each visit.

Follow-up time points:
4 weeks, 3 months, 6 months, 9 months, 12 months, 18 months, 24 months, 36 months, 48 months, 60 months, 72 months, 84 months, 96 months, 108 months, 120 months.

High-dose-rate brachytherapy will be performed for patients with low to intermediate risk prostate carcinoma. The treatment will include a single fraction of 19 Gy. High-dose-rate brachytherapy will be performed by insertion of catheters under ultrasound guidance. Under MR guidance, cathether placement will be adjusted, according to the exact tumour position.