The co-authors of Invasion of the Prostate Snatchers, blog alternate posts weekly. We invite you to post your comments.

Tuesday, May 7, 2013

Surgery vs. Seeds vs. IMRT

Many men with Intermediate-Risk prostate cancer consider treatment with radiation or surgery. Treatment selection is influenced by age and preexisting status, especially as regards baseline sexual and urinary function. These days “surgery” usually means robotic surgery rather than the older, “open” procedure. Brachytherapy (radioactive seeds), and intensity modulated radiation (IMRT) are the most widely used types of radiation.
Cure Rates
All treatment options result in similar cure rates assuming the best physicians and technology are used. If any single treatment can be considered to have a slight advantage, it is brachytherapy. Seed implants deliver a somewhat higher dose of radiation, possibly with slightly better accuracy. All types of radiation have a slight cure-rate advantage over surgery because radiation treats a small margin around the gland. Surgery, especially when extra-capsular disease is present, may leave cancer behind, an unfortuante situation called “a positive margin.”
Quality of Life
Since cure rates are equivalent, the main criteria for selecting treatment are side effects. Table 1 lists the risks faced by a 65-year-old with good erectile function and without preexisting prostate problems. Risks are adjusted up or down based on a man’s age and his sexual and urinary function prior to treatment.
Table 1 Long Term Side Effects
*Climacturia is the ejaculation of urine rather than sperm
**Stricture is a urethral scar

Short Term Side Effects
Some of the long-term effects noted in Table 1 also occur short term. All men are impotent after surgery though 50% eventually recover some functionality. Urinary symptoms, termed “urethritis,” occur in two-thirds of men who undergo brachytherapy, usually lasting a couple months. Proctitis symptoms lasting one to two months occur in about half of the men who are treated with IMRT.

Treatment for Long Term Side Effects
Shrinkage and shortening of the penis due to surgery may be partially averted with early use of Viagra, Cialis or Levitra, and when necessary, the injection of prostaglandins. For treating impotence or incontinence, patient satisfaction is about 85% with a surgically implanted penile prosthesis and 60% with a surgically implanted artificial urinary sphincter. Chronic urethritis, a non-healing radiation burn of the urinary passage, manifests as pain, frequent urination, and a compelling urge to urinate right now. Proctitis side effects can be described similarly, but affecting the rectum. Palliative treatments for chronic urethritis and proctitis are only partially effective.
Further Aspects of Surgery and Radiation
Surgery: The surgical skill of urologists varies and is measured by how frequently cancer is left behind after the surgery, termed a positive margin. The best surgeons average a 10% rate. Studies show that many urologists, even at reputable centers, leave cancer behind up to 50% of the time. Prostate removal gives information about the size and grade of the cancer, helping to improve the accuracy of projections about future relapse. Surgery also simplifies PSA monitoring, since unlike radiation, there is no residual prostate gland producing PSA.

Seeds: Brachytherapy with permanent seeds is an outpatient procedure. Temporary, high-dose-rate (HDR) brachytherapy requires an overnight stay in the hospital. Men with preexisting urinary problems or glands over 60cc are more prone to develop urethritis from brachytherapy. A benign PSA rise after the implant, termed a “PSA Bump,” occurs in 30% of men and can engender considerable anxiety.

IMRT treatment requires two months to deliver. Radiation beaming through surrounding organs may increase the risk of bladder and rectal tumors, though the risk is clearly less than one percent. The biggest risk besides impotence is proctitis. In the future, the injection of hydrogel between the prostate and the rectal wall may eliminate this risk (Hydrogel is pending FDA approval).

Cyberknife and Proton Therapy: Cyberknife is like IMRT but treatment is over one to two weeks rather than two months. Proton therapy is also similar to IMRT except it fires heavier subatomic particles (proton vs. photon). Proctitis rates are reported to be slightly higher with either of these two modalities.

Combination Radiation with Seeds and IMRT: Men with High-Risk disease and even some with Intermediate-Risk are treated with a combination of Seeds and IMRT. The side effects of Seed/IMRT combinations are similar to those of seeds alone.

The Outdated Sequencing Argument
As stated at the outset, cure rates are high with both radiation and surgery. Arguments touting surgery as the “Gold Standard” were true ten years ago when suboptimal radiation resulted in lower cure rates. Regrettably, to this day, many surgeons are still claiming that sequencing surgery before radiation is advantageous. This outdated thinking prioritizes planning for relapse, forgetting about the need to focus on quality of life. The goal is to be cured with the first treatment and be spared the side effects of additional rounds of therapy.

Taking Time to Decide
Prostate cancer is slow moving condition. There is no need rush to a decision. Radiation or surgery cures men with Intermediate-Riskprostate cancer 70-90% of the time. Even if a relapse occurs, salvage therapy usually gives a normal life expectancy. Additional options, besides surgery and radiation, can also be considered for men in the Intermediate-Risk category including active surveillance, focal therapy and intermittent hormone blockade. However, these treatments are outside the medical mainstream and beyond the scope of this short blog.


Anonymous said...

Your blog states that ->

"Proton therapy is also similar to IMRT except it fires heavier subatomic particles (proton vs. photon). "

In response ->

Protons have completely different characteristics from x-ray photons and proton therapy is not similar at all to IMRT.

Charged particles such as protons have an evident advantage over photons: they deliver their destructive power with a higher precision than photons, resulting in better sparing of normal tissues.

Whereas x-rays (photons) have their maximum dose near the surface (at the entrance) followed by a continuously reducing dose with depth, protons deposit almost all of their radiation energy at a specific tissue depth. The exact depth depends on the energy given to the proton beam, and this allows for very precise targeting of the tumor. Because practically all protons are absorbed at a specific point (namely, the tumor), normal tissues beyond the tumour receive very low to no radiation dose at all.

This is a scientific fact. Please investigate for yourself. Thank you.

Mark Scholz, MD said...

First of all, Ralph and I appreciate your reading our blog and engaging yourself by taking the time to respond. Your disagreement with my characterization of proton therapy possibly results from your misunderstanding of the purpose of the blog. I always have to guard against the temptation to wander away from my primary role, which is that of a clinical medical oncologist specializing exclusively in prostate cancer. (If you do even a cursory search you will discover that doctors with my degree of specialization in this area are very rare, less than 100 or so in the whole United States.) So while I have extensive knowledge about the physics of radiation therapy, digressing into basic science, interesting as it might be, will not be helpful to men with prostate cancer.

The point of Ralph’s and my blog is to use our expertise to offer assistance to the 250,000 men each year who are confused about what treatment to select. My writing is consciously designed to offer the viewpoint of an expert clinician providing expert advice about clinical outcomes that directly affect quality of life. In my experience the men who read this blog are looking for a bottom-line assessment of how treatment is going to impact them personally. Long technical explanations about brag peaks and particle characteristics are totally irrelevant if in the end you have a permanently burned rectum. So I stand by my original characterization of proton therapy, that from the viewpoint of clinical outcome, it is very similar to IMRT.

oldnurse said...

Can you comment about the linear accelerator equipment differences....proton and IMRT "equipment" differences? Are there equipment features that will improve the treatment outcomes?

Are older proton therapy centers equivalent to newer centers in terms of the "beam", and "outcomes" but specifically "side effects related to continence and bowel"
Thank you.

George Glass said...

Dr. Scholz, this is a very informative posts. Ive read so much about different treatment options but this article consolidates things well.

My question is whether your logic would apply as well to me since I'm only 49 years old, have gleason 4+3 (80% pattern 4), PSA 7.5, and two cores positive. If I was in my 60s I would definitely get IMRT brachy combo but Im not totally convinced because Im younger and have more time in the future for radiation side effects to take hold if I live into my 70s and 80s.

Can you please provide to me your thoughts and opinions based on my age and cancer data?

thanks in advance!