1: Novel tissue-sparing focal therapy may delay or prevent radical treatment for low risk prostate cancer

A Phase III clinical trial published in Lancet Oncology shows that vascular-targeted photodynamic therapy (VTP) may reduce the need for radical treatment in men with low risk (Gleason 3), localised prostate cancer. VTP is a focal therapy that uses a light activated drug (in this case Padeliporfin) to specifically target the tumour while sparing healthy prostate tissue and hopefully leads to less side effects compared to radical therapies such as prostatectomy or radiotherapy. This trial involved over 400 men in 47 European centres, and compared outcomes for men who had VTP to men who were placed on active surveillance. The aims of the study were to determine if VTP was safe and effective, and if its use could reduce the number of radical treatments for men with low risk prostate cancer. 

After a median follow-up of 24 months, men in the photodynamic therapy group had reduced disease progression compared to men on active surveillance (adjusted HR 0.34; 95% CI 0.24-0.46; p<0.0001). In addition, during this time, fewer men treated with VTP received radical therapy (6%) compared to men who were under active surveillance (29%). VTP treatment was associated with increased side effects compared to active surveillance. These largely occurred in the first 6 months and by 24 months post treatment both groups of men reported similar sexual and urinary function. Specifically, 30% of patients treated with VTP reported a serious adverse effect compared to 10% of men under active surveillance. For instance, 38% of VTP-treated men reported erectile dysfunction compared to 12% of men under active surveillance. Men undergoing VTP also had increased levels of haematuria, dysuria and urinary incontinence and retention.

This is the first prospective trial to compare a focal therapy to standard care for prostate cancer. A related trial which included men with Gleason 4 disease has also been completed and publication is expected later this year. The results of this trial show that VTP is safe and effective and suggest that it may reduce or delay the need for radical therapy. It will be important to see the results of longer-term follow to see how many men ultimately require radical therapy and if any later stage side effects emerge. Future work will also be important to develop better risk stratification tools for men with low grade localised prostate cancer, in order to reduce both over and under-treatment.

2: High selenium exposure is associated with decreased risk of prostate cancer

A new meta-analysis indicates that high levels of selenium are associated with reduced risk of a number of cancers including prostate, breast, lung and oesophageal. Selenium is an essential micronutrient found in food sources such as certain nuts, meat, mushrooms, fish and eggs and can also be ingested as a supplement. For the prostate cancer analysis, the authors included 25 studies which had prostate cancer as an outcome, and found that high selenium levels were associated with a decreased risk of prostate cancer (pooled OR=0.72; 95% CI:0.61-0.86) and that this association was dose-dependent. An all-cancer analysis, including 69 studies, also showed an association between increased selenium levels and decreased overall cancer risk (pooled OR=0.78; 95% CI:0.73-0.83). Importantly, this association was not seen when the analysis was limited to studies that involved selenium supplements (pooled OR = 0.91; 95% CI:0.80–1.03).

Previous studies have produced conflicting results, with high selenium being associated with both increased and decreased cancer risk. In addition, a large randomised controlled trial (SELECT) found no link between selenium supplement use and prostate cancer risk. This current meta-analysis suggests that at least some of the inconsistency may be due to differences between selenium that is taken as a supplement and natural (i.e. dietary) exposure. This study suggests that while selenium levels may effect prostate cancer risk, there is no convincing evidence to recommend the use of selenium supplements. In addition, these results indicate that at least some of the effect of selenium may derive from other nutritional components that exist within selenium-rich dietary sources.

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