If radiotherapy was more widely offered to men with prostate cancer, 41 early deaths and hundreds of treatment failures could be avoided each year in NSW alone, new research suggests.

The analysis of nearly 20,000 patients in the state found fewer than one-quarter had radiotherapy, whereas researchers suggest more than half stood to benefit from receiving radiotherapy at the time of diagnosis.

The findings, presented last week at the Clinical Oncology Society of Australia scientific meeting in Adelaide, suggest uptake of the treatment is still suboptimal despite it offering better outcomes and fewer side effects than surgery for select patients, the authors say.

Researchers, led by UNSW Sydney, analysed state prostate cancer registry data between 2009 and 2011 and found 65% of men had localised disease but only 18% received radiotherapy.