Commentary: Intermediate Risk

Notes for Commentary: Intermediate Risk: While the observations on the interactive graph are pertinent to the results of treatment, an individual decision for a particular treatment can be influenced by multiple factors. We strongly encourage scheduling consultations with Prostate Cancer Doctors specializing in the fields of Surgery, Brachytherapy and Radiation Oncology. Discussions with an expert in Medical Oncology can help you obtain a balanced perspective of the pros and cons surrounding each treatment.

Intermediate Risk disease is highly variable group of patients in terms of results and approaches. There is a wide variability of risk of disease beyond the gland ranging from 16-57% (please see the Partin Tables*) which can explain why the results vary widely. Also, the definitions are slightly different between centers, which makes comparisons more difficult.

What is the risk of disease is beyond the gland for intermediate Risk disease? The Partin Tables* can help determine for you, individually, what the risk might be. The good news is that, for many patients, intermediate risk disease behaves very similar to low risk disease and can be treated in a similar fashion. However, the physician must help each patient determine what the risk of disease is beyond the gland and individualize the treatment to treat all of the disease both inside and outside the gland.

On first glance at the graphs, it appears that brachytherapy approaches, with either permanent seed or HDR implants, are superior to the either surgery or external beam radiation. Why might there be an advantage to brachytherapy or combination of EBRT and seeds approaches? If you evaluate the Partin Tables* for intermediate risk patients, you will note that the risk of disease beyond the gland increases. Subsequently, it is logical that any treatment that just treats the prostate, such as surgery, has a higher risk of failing. However note that many of these patients can do well with local treatment such as surgery or seed implantation

Surgery for Intermediate Risk Disease
Surgery can be a good option for this group if the likelihood of disease beyond the gland is calculated to be low. Many patients in this category can have surgery. Surgery will fail in intermediate risk disease because of the existence of disease beyond the prostate which the surgery doesn’t treat. The calculation of disease beyond the gland using the Partin Tables* can be very helpful. If the risk of disease beyond the gland is low, surgery may be a very good option. Newer diagnostic test are attempting to determine which patients may do well with surgery.

External Radiation Beam Therapy (EBRT) for Intermediate Risk Disease
Because intermediate risk patients are at higher risk for disease beyond the gland, External Radiation for intermediate risk disease has the advantage over surgery of treating both the prostate and a wider area of potential spread. Conformal, IMRT (Intensity Modulated Radiation Therapy), Protons, Tomotherapy and Cyberknife are all forms of external beam radiation. Each has its own technical advantages but similar radiation doses, therefore the results are not expected to be comparably different in respect to cancer control. IMRT is the most common form of EBRT, with the most study results, but these only include a few long-term studies. Be aware that just because a therapy is new does not make it better. All of the external beam treatments give very similar biological doses (75-81 Gy equivalent) to the prostate and, therefore, produce similar results. The area treated beyond the gland, which may include the seminal vesicles and lymph nodes, is also similar. As can be seen in the charts, external beam treatments do well for approximately 60-80% of the patients in this intermediate risk category.

External radiation does a good job of treating the prostate and the area immediately around it where cancer can spread. For intermediate patients, external radiation likely fails due to an inability to give enough dose to control the disease in the prostate itself. The external dose that can be given to the prostate, by external beam techniques, is limited by the structures surrounding the prostate, primarily the rectum, bladder and hips. While techniques have been developed to minimize these areas receiving high doses, it is difficult to give doses beyond 75-81 Gy equivalent doses without a higher risk of rectal, bladder and hip injury.

Brachytherapy/Seed Implantation for Intermediate Risk Disease
Brachytherapy (Seed implantation alone) has a very low local failure rate in the Intermediate risk group. Local failure is reported to be approximately 1.4% in reported series. The reason is the dose delivered to the gland and tumor is considerably higher than external beam techniques. The dose with seeds are 120-145 Gy (dose equivalent) compared to 75-81 Gy for external beam. The reason seeds can deliver a higher dose to the cancer is that the seeds are placed directly into the gland and tumor. The dose from the seed falls off rapidly, resulting in lower doses to the bladder, rectum and hips than external radiation.

Many intermediate patients behave similarly to low risk patients and can be treated with seed implantation alone. The Partin Tables* can help determine for you, individually, what the risk might be of disease beyond the gland and whether seed implantation alone is appropriate. Typical seed implant techniques also include the area where the cancer spreads and the planning for an implant always includes the area around the nerve where most of the extraprostatic disease is found.

Brachytherapy Alone vs External Beam and Seeds for Intermediate Risk Disease
The value of external beam radiation (EBRT) with seeds is its potential to treat a wider area than seeds alone. This estimate of need for external beam for seeds takes into account the Partin Table* calculation of risk beyond the gland, the number of biopsies that are positive, the risk of seminal vesicle involvement and whether there is nerve invasion. Each of these factors may influence your doctor’s opinion on the value of EBRT. The data from the charts do not provide a clear distinction on which patients should get seeds alone versus combined EBRT and seeds. Surveys of experts to ask their opinion on what treatment they might give for each clinical situation they might encounter in this group have been done and are available here. These opinions can be discussed with your physician, to help decided on the most appropriate approach in your situation.

Implantation alone, or in combination with EBRT, appears, on the charts, to do better than either surgery or external beam radiation. Seed implantation is likely better than surgery in intermediate risk disease due to the high local control rate of seed implantation and its ability to treat an area beyond the capabilities of surgery. Since external beam and seed implantation techniques treat a similar volume beyond the prostate, seed implantation with or without external beam radiation is likely better than external beam radiation because of the substantially higher dose to the prostate. Therefore, seed implantation techniques may do slightly better overall than surgery or external beam because it gives more dose to control the cancer in the prostate than external beam radiation and does better than surgery, which has excellent local control, because the implant techniques are designed to control the disease beyond the gland.

* Partin Tables – The Partin Tables use clinical features of prostate cancer – Gleason score, serum PSA, and clinical stage – to predict whether the tumor will be confined to the prostate. The tables are based on the accumulated experience of urologists performing radical prostatectomy at the James Buchanan Brady Urological Institute. For decades, urologists around the world have relied on the tables for counseling patients preoperatively and for surgical planning. Click for more information