University College Hospital in London. Courtesy of Steve Parkinson via Creative Commons.
Standard prostate cancer treatments, such as prostatectomy surgery or radiotherapy, often lead to substantial side effects. These include erectile dysfunction (affecting 30-70%) and urinary incontinence (affecting 5-20%). However, these unwanted side effects could be reduced, if prostate cancer treatments could target just the cancer tumors while harming less of their surrounding healthy tissue.
A promising “proof of concept” research study has just demonstrated that a new technique to treat localized prostate cancer may significantly reduce side effects compared to standard treatments. This study was carried out by researchers from University College London and the results were just published in the peer-reviewed medical journal The Lancet Oncology.
This new treatment uses high-intensity focused ultrasound (HIFU) to target and destroy prostate tumors, while causing minimal damage to their surrounding nerves and muscles. A small ultrasound probe is placed close to the prostate through the patient’s rectum. This probe emits a narrow beam of intense sound waves that heat the targeted cells to 80 C for one second, killing a targeted area about the size of a grain of rice. The probe is then moved to focus and destroy additional cancerous areas. The procedure is performed in the hospital under general anesthesia and most patients are back home within 24 hours.
Surgeon Hashim Ahmed from University College Hospital in London demonstrates in a BBC News short video how this probe heats only a small target area.
The “proof of concept” HIFU study was primarily focused on assessing the frequency and extent of side effects, rather than the success of the prostate cancer treatment. Forty-one men participated in the study, ranging in age from 45 to 80 years old. All participants had localized prostate cancer ranging from low to high risk, where 30 men (73%) had intermediate to high-risk disease. They also had a prostate volume of 40 mL or less in order to avoid an excessively long procedure. They had received no previous prostate treatment.
The prostate cancer tumor locations were identified using multiparametric MRI (magnetic resonance imaging) and a template-prostate-mapping biopsy. The identified tumors were then targeted by the HIFU treatment. The men were followed up at one, three, six, nine and twelve months after the HIFU procedure. Each follow-up included: (1) a PSA blood test to measure the levels of prostate specific antigen protein being produced by the prostate, since PSA is generally elevated for men with prostate cancer; and (2) questionnaires that evaluated side effects. In addition, the MRI and biopsy tests were repeated as part of the 6 months follow-up and an additional MRI was performed after a year.
Researchers found that a year after the HIFU treatment, 89% of the men still had erectile function and all were still continent. In addition, there was a significant decrease in PSA levels compared to baseline and 95% of the men showed no evidence of disease on the final MRI scan.
Clearly this HIFU pilot study has demonstrated a promising reduction in treatment side effects. However, it was a small observational study of 41 men and followed them for only a year. The results need to be confirmed by much larger clinical trials that assess both the effectiveness and safety of HIFU compared with standard therapies. As a result, the researchers at University College London have started recruiting patients for a larger phase 2 trial that will follow patients for 3 years.