Men may delay radiation therapy after prostate cancer surgery

There appears to be no pressing need for men with prostate cancer to undergo radiotherapy immediately after surgery, according to a recent study presented at the 2019 Congress of the European Society of Medical Oncology (ESMO 2019).

“The results suggest that radiotherapy is equally effective whether it is given to all men shortly after surgery or given later to those men with recurrent disease,” said study first author Prof Chris Parker of The Royal Marsden NHS Foundation Trust and Institute of Cancer Research in London.

“There is a strong case now that observation should be the standard approach after surgery and radiotherapy should only be used if the cancer comes back,” he added.

The likelihood of biochemical progression-free survival was comparable between men who received radiotherapy soon after surgery (adjuvant group) and those who deferred the procedure (salvage group; hazard ratio [HR], 1.10, 95 percent CI, 0.81–1.49; p=0.56). [ESMO 2019, abstract LBA49_PR]

The same was true for the freedom from the need of hormone therapy not prescribed in the study protocol (HR, 0.88, 0.58–1.33; p=0.53).

In terms of safety, researchers documented greater urinary morbidity, as measured by the radiation therapy oncology group (RTOG) scale, in the patients who received immediate radiotherapy. For instance, within 2 years of treatment, 2 percent of the adjuvant group developed cystitis of at least grade 3, as opposed to only 0.7 percent of the salvage group.

In the same time frame, similar patterns were reported for haematuria (3 percent vs 0.3 percent) and urethral stricture (5 percent vs 4 percent) grade ≥3. The trends persisted until 2 years after intervention.

There were also gastrointestinal safety issues. Diarrhoea (1 percent vs 0.4 percent) and proctitis (1 percent vs 0.4 percent) occurring within 2 years of intervention were more common in the adjuvant vs salvage groups. The same was true when prevalence was assessed after 2 years (diarrhoea: 1 percent vs 0.3 percent; proctitis: 1 percent vs 0.2 percent).

“The good news is that in future, many men will avoid the side-effects of radiotherapy,” Parker said. “These include urinary leakage and narrowing of the urethra, which can make urination difficult. Both are potential complications after surgery alone, but the risk is increased if radiotherapy is used as well.”

In the present study, 1,396 men were randomized after undergoing radical prostatectomy: 697 received adjuvant radiotherapy (median age, 65 years), while 699 were assigned to the salvage therapy policy (median age, 65 years). The respective median prostate-specific antigen levels at diagnosis were 8.0 and 7.8 ng/mL in either group.

Over a median follow-up of 5.0 years, researchers assessed several clinical outcome measures, such as biochemical progression-free survival, freedom from nonprotocol hormone therapy and treatment safety.

Overall survival was also designated as a study outcome, though the study was sufficiently powered to only assess it in men who underwent salvage radiotherapy. Twenty-six deaths were reported in this group, with prostate cancer accounting for eight of them.

Freedom from distant metastasis was set as the primary outcome, but the study was similarly underpowered to assess it. Twenty-two such events were reported in the salvage arm.

According to the researchers, while the present findings support a more passive approach to radiotherapy after prostate cancer surgery, future studies with longer follow-up time frames are needed to determine the effect of radiation timing on distant metastasis.