ProtecT study: Radiotherapy performs best in the long term

Whether radiotherapy, surgery or active surveillance - the disease-free survival of patients with localized prostate cancer is still the same 15 years after treatment, regardless of which treatment they chose. However, radiotherapy has the best balance in terms of risk-benefit assessment: it prevents relapses just as well as surgery, but at the same time has fewer side effects. This is the result of the 15-year follow-up of the British long-term study ProtecT ("Prostate Testing for Cancer and Treatment Trial"), which was recently published in the renowned New England Journal of Medicine.

Long-term comparison between radiation, surgery and active monitoring

The ProtecT study is the first to enable a direct long-term comparison between radiotherapy of the tumor and surgical removal of the prostate and monitoring of the tumor (active surveillance). To this end, scientists from the University of Oxford and Bristol examined a total of 1643 patients with localized prostate cancer who were randomly assigned to one of the three treatment options. The follow-up period is now 15 years. During active surveillance, PSA levels were checked every three months in the first year and then every six to twelve months in order to initiate treatment if necessary if they increased by more than 50 percent.

The study shows that the disease-specific mortality rate in patients whose tumor is confined to the prostate is extremely low, even in the long term, regardless of whether the patients were irradiated, operated on or actively monitored. According to the results, the average survival rate 15 years after diagnosis is 97 percent. "Even against the background that the radiotherapeutic procedures used in the study no longer correspond to the current standard, there is no survival advantage for surgery," emphasizes Dr. Stephan Neubauer, head urologist at the West German Prostate Center.  

Active monitoring: frequent metastasis

The situation was different with active surveillance: after 15 years, cancer progression and the formation of metastases occurred more frequently. "Thanks to the rapid progress in medical technology, however, such differences can now presumably be minimized," admits Dr Neubauer. "With imaging techniques such as multi-parametric MRI, we can better assess the aggressiveness and extent of the tumor and thus determine the tumor stage more precisely at the time of diagnosis. At the same time, tissue removal from the prostate is now much more targeted, so that progression of the disease can be detected more quickly under active monitoring and treatment can be initiated at an early stage," says the urologist.

More side effects after surgery  

While the probability of survival is almost the same for surgery and radiotherapy, there are major differences in terms of possible side effects, as another working group at the University of Bristol was able to prove. Patients from the ProtecT study were surveyed over 12 years with regard to side effects and complications.

According to the results, the biggest differences between surgery, radiation and active surveillance were in the ability to hold urine and sexual function. After 7 to 12 years, 18 to 24 percent of patients in the surgery group experienced urinary incontinence requiring pads, compared to 9 to 11 percent in the active surveillance group and 3 to 8 percent in the radiotherapy group. The effects on the men's potency were also greatest after the operation. While 67 percent still had an erection that enabled them to have sexual intercourse before the start of the study, after six years it was only 18 percent compared to 27 percent after radiotherapy and 30 percent after active monitoring.

Brachytherapy even gentler

"With modern methods of radiotherapy such as internal radiation (brachytherapy), the side effects of treatment can be reduced even further," emphasizes Dr. Neubauer. In LDR brachytherapy, for example, tiny radiation sources (seeds) are introduced directly into the tumor. The seeds remain there for several months and deliver high-dose radiation to the tumor tissue in a targeted manner. This has the advantage that the tumor is destroyed without damaging surrounding healthy tissue such as the bladder, colon or sphincter. As a result, the patient's urinary incontinence rate remains at a very low level even years after the end of treatment, according to the urologist from Cologne. The same applies to external forms of radiation such as intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT).

Conclusion

According to current data, radiotherapy is the best procedure for localized prostate cancer, summarizes the German Society for Radiotherapy (DEGRO). According to DEGRO, it offers greater safety against recurrence than active monitoring alone and is absolutely comparable to surgery in terms of disease-free survival, but with the major advantage of fewer side effects and long-term consequences.