Improved diagnosis of clinically relevant prostate
In Europe prostate cancer (PCa) is currently the most commonly diagnosed cancer in men- around one in six in the West will eventually be diagnosed with the disease- but the majority of patients will die of unrelated causes. There are two major problems related to PCa diagnosis: firstly, because of the lack of a highly sensitive and specific biomarker, many elderly men without cancer, or with clinically insignificant tumours confined to the prostate gland, are still undergoing unnecessary biopsies. Secondly because of its random nature, the standard method of biopsy, the transrectal ultrasound biopsy (TRUS), frequently detects low risk cancers that do not need aggressive therapy but fails to detect many clinically significant tumours in the less accessible areas of the gland. Recent studies suggest that multiparametric MRI (mp-MRI) pre-biopsy, to identify suspicious areas, followed by targetted biopsy using MR-ultrasound fusion, which combines detailed MRI scans with real-time ultrasound images of the prostate, is the better approach.
One preliminary prospective cohort study reported last year was carried out at the US National Cancer Institute. During a seven year period more than 1000 men underwent mp-MRI followed by MR-ultrasound fusion and concurrent TRUS. Whole-gland pathology of the prostate was also carried out after any prostatectomies. It was found that MR-ultrasound fusion diagnosed 30% more high risk tumours and 17% fewer low-risk tumours than TRUS. However data are still needed on disease recurrence and PCa mortality, and the authors consider that random clinical trials should be carried out to determine eventual clinical outcomes. A retrospective analysis involving more than 600 Brazilian patients with suspected PCa was also reported recently with 286 patients undergoing MR-ultrasound fusion biopsies and 331 patients undergoing random ultrasound-guided biopsies. Again the former technique detected significantly more patients with high-risk cancer requiring surgery and significantly fewer low-risk tumours where only surveillance was needed. There are of course financial impacts of purchasing and using such technology, but improved patient risk stratification may well result in a negligible net cost increase.
Hopefully MR-ultrasound fusion can replace techniques such as TRUS for suspected PCa diagnosis, but a question still remains. Is it really always necessary to treat clinically significant PCa by radical prostatectomy or radiotherapy of the entire organ when erectile dysfunction, urinary incontinence and intestinal problems are such common side effects? Would it not be possible to utilize appropriate imaging technologies and confine treatment to the affected area of the gland?