A recent study published in “The Red Journal” suggests (perhaps not surprisingly) that radiation oncologists and urologists have different mindsets about the application of immediate adjuvant radiation therapy following surgery for prostate cancer patients with a variety of adverse pathologic risk factors.
Showalter et al. invited 926 radiation oncologists and 561 urologists to complete a web-based survey that asked questions about these physicians’ policies and beliefs regarding immediate adjuvant radiation therapy. The adverse pathologic risk factors that were specifically listed as being potential indicators for adjuvant radiation included:
- Extracapsular extension
- Seminal vesicle invasion
- Positive surgical margin(s)
Here is what they found:
- The overall response to the survey was only 20 percent.
- Surveys were completed by
- 218/926 radiation oncologists (23.5 percent)
- 92/519 urologists (17.7 percent)
- Based on the adverse pathologic features provided, adjuvant radiation was recommended by
- 68 percent of all respondents
- 78 percent of radiation oncologists who responded
- 44 percent of urologists who responded
- Urologists were significantly less likely than radiation oncologists to agree that adjuvant radiation improves survival and/or biochemical control (p < 0.0001).
- PSA thresholds for salvage (as opposed to adjuvant) radiation therapy were higher among urologists than among radiation oncologists (p < 0.001).
- Predicted rates of erectile dysfunction as a consequence of radiation therapy were higher among urologists than among radiation oncologists (p <0.001).
- On multivariate analysis, respondent specialty was the only predictor of recommendations about use of adjuvant radiation therapy.
There are most certainly data that suggest that immediate adjuvant radiation therapy can extend the overall survival of men with high-risk features after first-line radical prostatectomy. However, the data from these trials are perhaps not as compelling as some would like to believe. One of the major trials (in the USA) that attempted to address and resolve this question never enrolled sufficient patients. Another, carried out largely in the UK, combined adjuvant radiation with adjuvant hormone therapy, which is a much more aggressive form of treatment.
The basic problem here is that we have really failed — to date — to differentiate between the value of adjuvant radiation and salvage radiation therapy based on all the risk factors for individual patients. There might well be consensus between the urologists and the radiation oncologists that adjuvant radiation (perhaps with neoadjuvant and adjuvant hormone therapy too) was a good idea for this patient:
- GK is 52 years of age, diagnosed with a PSA of 4.8 ng/ml, Gleason 8, with 7/12 positive biopsy cores. After robot-assisted surgery he is pT3a, still Gleason 8, with one positive surgical margin, and an initial nadir PSA of 0.18 ng/ml.
However, its value in the following patient is not as immediately evident:
- RL is 67 years of age, diagnosed with a PSA of 4.9 ng/ml, Gleason 8, with 5/12 positive biopsy cores. After robot-assisted surgery he is pT3a, still Gleason 8, with negative surgical margins, and an initial nadir PSA of 0.01 ng/ml.
At present the appropriate use of immediate adjuvant radiation therapy is really a judgment call, based on the individual characteristics of the individual patient and on the risks that that patient is willing to take. It is hardly surprising that most surgeons want to take some time to see if the patient is in full remission after a radical prostatectomy. By comparison, it is also hardly surprising that the radiation oncologists want to give adjuvant radiation early — when the chances of it working best in the men who most need adjuvant radiation are at their highest.
As Showalter et al. note in their conclusions, what we really need is further research to better define the toxicities of second-line radiation therapy in patients who have received first-line radical prostatectomy and on better identifying subgroups of patients who will really gain from immediate adjuvant radiation therapy as compared to deferred (salvage) use of radiation.