ESTRO38 Congress Report

5. BEST JUNIOR PRESENTATION SPONSORED BY ELEKTA BRACHYTHERAPY

Clinical outcomes of focal salvage high-dose-rate brachytherapy for radiorecurrent prostate cancer. Max Peters, Marieke J. van Son, Marinus A. Moerland, Jan J.W. Lagendijk, Jochem R.N. van der Voort van Zyp.

UMC Utrecht, Radiation Oncology Department, Utrecht, The Netherlands.

Context of the study A substantial proportion of patients undergo radiotherapy for prostate cancer. Depending on the degree of tumour extension and biologic aggressiveness, recurrences remain quite common after treatment. The recurrence can often be localised to the site of the original cancer. In the past, re-treatment of the whole prostate with salvage surgery or radiotherapy were the only potentially curative options. However, due to previous radiation induced damage to surrounding organs such as the rectum, bladder, urethra and neurovascular bundles salvage whole gland therapy leads to significant morbidity with frequent side-effects with a high impact on quality of life. Traditionally the alternative option would be non-curative androgen deprivation therapy in order to suppress the prostate cancer. This is in essence a palliative treatment, as eventually resistant cancer clones develop requiring the need for second line systemic treatments such as chemotherapy in those fit enough to receive it. With the development of new imaging techniques allowing accurate disease localisation such as multiparametric MRI and improvements in our targeting ability and treatment delivery, re-treatment of only the areas containing recurrent prostate cancer rather than the whole prostate has become possible. This is called focal therapy and can lead to potentially curative oncological control of the cancer whilst reducing side effects by limiting the damage to surrounding organs and thus preserving quality of life for the patient. Overview of abstract In patients who have already undergone radiotherapy, treating only the recurrent prostate cancer lesion in a focal manner instead of the whole prostate could reduce side- effects and preserve quality of life, whilst still providing a potentially curative treatment option to the patient. The purpose of this work was to describe the clinical outcomes of 96 patients with an MRI visible localised radio-recurrent tumour treated with single-dose (19 Gy) focal salvage high-dose-rate brachytherapy, at a median follow-up of 11 months. Outcomes of interest were toxicity (measured with the CTCAE 4.0), quality of life (measured with validated questionnaires) and (biochemical) disease free survival. What were the three main findings of your research? 1. Side-effects of single-dose focal salvage high-dose-rate brachytherapy are uncommon (severe genitourinary side- effects occurring in only 2% of patients). 2. Corresponding with this, quality of life was virtually unaffected. Only a transient increase in urinary symptoms was seen in the first month. 3. At two years follow-up, biochemical disease- free survival was 77% (95% CI 65-91%), metastases-free survival 84% (95% CI 73-92%) and overall survival 98% (95% CI 93-100%).

What impact could your research have? Results from focal (MRI-guided) re-treatment of prostate cancer have been promising and notwithstanding the lack of randomised data the improvements in QoL and functional outcomes when compared to the traditional whole gland treatments warrant a discussion on focal salvage therapy becoming the new standard of care for patients with localised radio-recurrent prostate cancer. This could reduce or delay the need for palliative hormonal therapy, chemotherapy and reduce treatment related side-effects whilst concurrently maintaining quality of life. Is this research indicative of a bigger trend in oncology? Focal therapy, especially for prostate cancer, is a major research area, in both the radiation oncology and urology communities. Traditional whole gland treatments have carried significant morbidity for the patients and a major attraction to both clinician and patient from focal therapy has been the promise of oncological control whilst minimising treatment related adverse events. In radiation oncology, MRI-guidance with the development of MRI-guided external beam radiotherapy systems and consequently the possibility of dose-escalation and hypofractionation are increasingly popular topics in many tumour sites. Focal salvage MRI- guided high-dose-rate prostate brachytherapy incorporates many of these elements including image guidance, with a single session of high dose treatment administered in a focal manner to only the recurrent tumour. Alongside the pursuit of long term and randomised clinical data, in the future, technological advances in focal therapy will continue to develop with robotics seen as the next step to full MRI- guidance during treatment.

Congress report | AWARDS

53