A major study has confirmed that androgen deprivation is just as safe and effective at 18 months as three years, spelling good news for men’s return of sexual function and chance of osteoporosis.
The biggest cancer trial in Australia and New Zealand included more than 1000 men with locally advanced prostate cancer and randomly assigned them to treatment with either short- or long-term hormone treatment in combination with radiotherapy.
Lead author Conjoint Professor Jim Denham, a Newcastle radiation oncologist, said that when compared with six months of hormone and radiation therapy, 18 months of hormone therapy cut prostate cancer death by 30% and metastases by 40% over the decade-long follow up.
And those in the longer treatment arm suffered no additional side effects.
The baseline therapy was six months of testosterone suppression therapy with leuprorelin and radiation therapy, with one of the groups having an additional 12 months of hormone suppression therapy compared with no intervention.
Around 17,000 Australian men are diagnosed with the cancer each year, and until recently, the most beneficial regimen was thought to be 28 to 36 months of androgen suppression together with prostatic and pelvic nodal radiotherapy.
Despite the toxicity and impact such a duration had on patient-reported outcomes, many patients around the world were still subjected to androgen suppression for these long periods, the authors wrote.
Professor Sanchia Aranda, CEO of Cancer Council Australia, said the study was important because androgen therapy caused significant side effects, such as sexual dysfunction and osteoporosis or bone fractures, and so good justification for its use was required.
This research showed that it was likely that longer courses, such as 36 months, of androgen deprivation therapy could be avoided in the context of increased doses of radiotherapy, she said.
“The study also shows that the addition of zoledronic acid (to reduce the osteoporosis and prevent fractures), which causes flu like symptoms, tiredness, dizziness, vision disturbance, diarrhoea and others) does not improve survival and did not prevent bone metastases in these patients,” Professor Aranda said.
As a result, its value was unclear in this group and should be further studied in clinical trials, she added.
Meanwhile, Melbourne researchers have highlighted the link between a diet high in saturated fatty acids and aggressive prostate cancer. They found that prostate cancer cells take up fatty acids, causing the cells to grow. When they genetically deleted the key fatty acid transporter, cancer growth was slowed.
While there has been an established link between dysfunctional fatty acid metabolism and many chronic diseases for many years, “providing the evidence to develop a therapy to treat a disease that impacts so many men is deeply satisfying”, study co-author, University of Melbourne physiology department head Professor Matthew Watt, said.
Professor Watt and his colleagues hoped their findings could underpin therapies preventing men from developing advanced stage cancer.
Lancet Oncol; 20 Feb
Sci Transl Med; online 6 Feb