MRI Assisted Focal Boost With HDR Monotherapy for Prostate Cancer Patients

MRI Assisted Focal Boost Integrated With HDR Monotherapy Study in Low and Intermediate Risk Prostate Cancer Patients (MARS)

Radiation therapy plays an important role in the management of prostate cancer. In recent years it has become evident that higher doses of radiation are required to optimize disease control. The limiting factor of escalating dose to the prostate is the surrounding normal tissue. Despite advances in escalating radiation therapy, failures still occur in 20-30% of patients most often at the site of the original primary disease. As such there is growing interest in further dose escalating to the area of primary disease burden.The aim of this work is to look at the feasibility and toxicities of an integrated focal boost to whole gland prostate treatment using high dose rate brachytherapy.

This study is a pilot study of 60 patients look at the toxicities, biochemical and patient reported quality of life outcomes of an MR-integrated focal boost using HDR prostate brachytherapy. Eligible patients for this study will be determined by pre-brachytherapy MRI (DCE, T2 weighted and diffusion weighted) imaging, to identify a dominant intraprostatic lesion. The HDR dose prescription is 19 Gy to the whole gland ad 22.5 Gy to MRI visible lesion delivered in one fraction, assuming that dose constraints to critical organs can be met.

Inclusion Criteria:

1. Histologically confirmed diagnosis of adenocarcinoma of the prostate
2. Low and Intermediate risk disease defined as T1-T2c, Gleason < 7 and PSA < 20 ng/ml.
3. Prostate volume < 60 cc as determined by US, CT or MRI
4. Ability to undergo MR imaging
5. Provide written informed consent
6. Identified MR nodule (PIRADs 4/5)

Exclusion Criteria:

1. Ineligible for MR imaging due to contraindications
2. Documented nodal or distant metastases
3. Previous pelvic radiotherapy
4. Previous trans-urethral resection of prostate, previous prostatectomy or HIFU
5. Use of androgen deprivation therapy. Use of 5-alpha-reductase inhibitors permitted
6. Poor baseline urinary function defined as International Prostate Symptom Score (IPSS) >15
7. Contra-indication to radical prostate radiotherapy e.g. connective tissue disease or inflammatory bowel disease
8. Significant medical co-morbidity rendering patient unsuitable for general anaesthetic