A phase 2 trial led by researchers from the Royal Marsden NHS Foundation Trust and the Institute of Cancer Research has revealed that radiotherapy in combination with hormone therapy could delay the need for chemotherapy in patients with advanced prostate cancer.
Recently presented at the European Society for Radiotherapy and Oncology’s annual congress, the TRAP trial was funded by Prostate Cancer UK and sponsored by the Royal Marsden.
Responsible for more than 44,000 new male cases in England annually, advanced prostate cancer occurs when cancer spreads from the prostate to other parts of the body.
Researchers investigated whether giving stereotactic body radiotherapy (SBRT) in combination with androgen receptor-targeted agents – a type of hormone therapy – to patients with oligoprogressive prostate cancer would delay cancer progression across several cancer centres in the UK.
Oligoprogressive prostate cancer occurs when cells from the original tumour travel within the body to less than three sites, forming new tumours or lesions.
SBRT helps clinicians target tumours with sub-millimetre precision to deliver radiation with pinpoint accuracy while preventing damage to surrounding health tissue.
Researchers treated 81 patients – 67% of whom had one oligoprogressive lesions – with five or six SBRT treatments in the bone (59%), lymph node (32%), prostate (8%) and lung (1%).
Results showed that at around 19 months, 65% of patients experienced progression of their disease, while 32% progressed within six months following SBRT treatment and had a median progression-free survival of 6.4 months, with 40% of men having no evidence of cancer growth 12 months after treatment.
In addition, 84% of 43 patients saw a significant decrease in their prostate-specific antigen (PSA) levels in the blood, compared to 45% of those who did not progress or die within six months, meaning that PSA could be used to indicate whether SBRT will work for a longer period of time.
Researchers now hope to find evidence that could help change the standard of care for advanced prostate cancer patients.
Simon Grieveson, assistant director, research, Prostate Cancer UK, commented: “Whilst these results offer great promise for men with advanced prostate cancer…, this now needs to be tested in a larger randomised study,” known as the STAR TRAP trial.