Choosing Between
Tomotherapy
Brachytherapy (HDR),
Or a Combination

At our Tulsa CTCA clinic, we offer three popular and successful treatment options for prostate cancer:

• Tomotherapy
• High dose rate (HDR) brachytherapy
• Combination therapy with HDR and Tomotherapy

Tomotherapy is an advanced form of external beam radiation (IMRT / IGRT) with precise targeting of the prostate gland. HDR brachytherapy uses a radioactive pellet which is temporarily placed inside the prostate gland and irradiates the prostate from the inside.

Each of these three choices offers advantages and drawbacks. The choice should be based on how aggressive the cancer is, overall health, prostate size, whether there is more emphasis on aggressive treatment or reduced side effects, and personal time constraints.

Dose and Time Comparisons

For HDR brachytherapy on its own we do a single implant procedure, keep the plastic needles in the prostate for 33 hours, and give 4 treatments through the needles over that time period.

For tomotherapy on its own we give 35 - 45 treatments over a 7 - 9 week period.

For HDR + Tomo combination therapy: We do a single brachytherapy implant procedure, keep the plastic needles in place for 27 hours and give three treatment through the needles over that time period. After a two week break, we then give tomotherapy for 20-25 treatments over 4-5 weeks.

The actual prescribed doseages are

• HDR alone = 925 cGy * 4 = 3700 cGy
• Tomo = 225 cGy * 33 = 7425 cGy
• HDR + Tomo = 600 cGy * 3 + 225 cGy * 20 = 6300 cGy

All of these treatments use daily dosages that are greater than the standard of 180 - 200 cGy per day. For this reason, these treatments have a much larger effect on the cancer than standard saily dosages of radiation. A treatment of 400 cGy is not only twice as strong as a 200 cGy treatment, it is almost three times as strong in its ability kill cancer cells. This is why for HDR, 4 treatments of 925 cGy will equal 3700 cGy if you calculate it on a calculator, but if you take into account how much more powerful these treatments are, it is theoretically equal to 9400 cGy. It is theoretical because these calculations have not been completely proven. It is uncertain if those 4 fractions of HDR are really equal to 9400 cGy. Even though the HDR alone seems to give a very high dose, clinically I would say that the combination treatment gives the highest dose.

Standard radiation methods give approximately 6600 - 7200 cGy of radiation to the prostate. All three of our regimens give doses that are well beyond conventional dose/fractionation levels.

Patient Selection Issues

For HDR alone, the radiation is given fairly tightly within the prostate gland. The cancer should be very early. We suggest that the cancer be on one side of the prostate gland only, that the biopsy cores contain a relatively low amount of cancer, that the PSA be less than 10, and the Gleason score be less than or equal to 6 (3 + 3 = 6). For HDR alone, the implant must be perfect. There is no back-up external radiation given. For this reason the prostate gland should not be very enlarged. We prefer 40 - 50 cc or less. It may be necessary to shrink the prostate gland first with Lupron.

For Tomotherapy alone, the treatment is very versatile. Extra margins can be added beyond the prostate. Seminal vesicles or lymph nodes can be included if desired. The PSA, gleason, and stage can all be early or advanced. The prostate gland can be any size, and there is no need to shrink the gland. Lupron is not used to shrink the prostate, but sometimes it is added to help the cure rate in aggressive cancers.

For HDR + Tomo, the treatment can also be used to treat a very large range of PSA, Gleason scores, and stages. The prostate should be of a reasonable size, we prefer 50 cc or less. The Tomo portion can be used to treat a broad area if necessary, and the HDR will provide a "boost" to the prostate where a higher dose is needed. The HDR may not be able to cover all cancers with obvious spread outside the prostate gland.

Results of the Three Programs

For HDR alone, there are very few articles published. No one knows what the optimum dose to use is. No one knows if the dose equivalency calculations I showed above are completely accurate. The articles that have been published do show promising results. A Japan study showed a somewhat low 55% five-year recurrence free rate. A Michigan study had a 98% control rate at an average 3 year follow-up. Oakland has a 96% 5-year PSA control rate. It must be remembered that these U.S. studies show early results, with ideal patients with early cancers.

For Tomotherapy alone, there is a large body of experience looking at IMRT, as well as a foundation based on older 3D-conformal techniques. At Memorial Slone Kettering, the 3 year PSA recurrence free rate for IMRT was 92% for early cases.

For the combination of HDR + External Beam, we have had experience with approximately 900 men who have had this treatment combination at our center. Our 5-year PSA control rate for men with early prostate cancer is 97%, for men with intermediate risk cancer it is 92%, and for men with high risk cancer it is 72%. In Oakland, the 10-year PSA control rates were 90%, 87%, and 69% for low, intermediate, and high risk patients. There are many published results available for the combination of HDR + IMRT.

Side Effects

HDR brachytherapy may cause urethral strictures. A stricture is scarring and narrowing of the urethra as it passes through the prostate gland. If it occurs, it can be treated by dilating (stretching) the urethra, or by cutting out the scar tissue. It can be a recurrent problem.

Any form of radiation or brachytherapy can affect the erectile nerves and blood vessels, making erections difficult to obtain. Our definition of impotence is the percentage of men who were fully functional before treatment, who now require Viagra or other help to obtain erections at 24 months following treatment.

HDR brachytherapy requires general anesthesia, and multiple needles inserted into the body which remain in place for 24 - 36 hours. It is uncomfortable. It can be risky for men with multiple medical or cardiac problems.

Tomotherapy can theoretically cause more damage to the bladder and rectum, but there have been such tremendous advances in technology that an entire treatment course of Tomotherapy is usually highly well tolerated during and after treatment.

The following are my estimations of the side effects rates based on our experience and others:

HDR alone causes a 7% risk of urethral strictures, 20% risk of impotence, a 0% risk of rectal problems, and 2% risk of incontinence.

Tomotherapy alone causes a 2% risk of urethral strictures, 30% risk of impotence, 4% risk of rectal problems, and 2% risk of incontinence.

HDR + IMRT causes an 8% - 15% risk of urethral strictures, 40% risk of impotence, 1% risk of rectal problems, and a 2% - 3% risk of incontinence.

SUMMARY

Choose HDR alone for its convenience and few side effects. Choose IMRT alone as the conservative all-around option. Choose HDR + IMRT as the most aggressive treatment.

High Dose Rate Brachytherapy (HDR) as the Sole Treatment

This is also covered in the monotherapy webpage. HDR monotherapy is a good option for men with small or averaged sized prostate glands, who have a very early prostate cancer. If the prostate is large, it will need to be shrunken first with Lupron. Although the early results and thereotical dose calculations are promising, it is the least researched option, and hence the one with the greatest unknowns in terms of long term side effects and cancer control rates. It is highly convenient time wise, and results in the least chance of impotence of the three choices. The radiation oncologists at CTCA approach its use cautiously.

Tomotherapy as the Sole Treatment

This is also covered in the IMRT webpage. Tomotheray (IMRT) alone is a conservative approach, that can be used for virtually any cancer stage, as long as the cancer has not metastasized. There is no need for surgical anesthesia and placement of brachytherapy needles. There is no need to shrink the prostate gland first with Lupron. Lupron is added when the cancer is aggressive, and IMRT may be the optimal treatment for patients who have obvious cancer in the lymph nodes, seminal vesicles, or extending beyond the prostate capsule.

Combination Treatment with HDR and Tomotherapy

This is also covered in the general prostate brachytherapy web pages. HDR + IMRT is, in my opinion, the most aggressive of the three options. Theoretical dose calculations aside, I believe that it offers the most intense dose to the prostate gland. This is probably reflected by the fact that it causes the most urethral strictures. The urethra passes through the center of the prostate gland, and whatever dose the cancer gets, the urethra gets. HDR + IMRT may be overkill for very early cancers, but many patients would rather choose overkill than risk underkill. For younger men or for aggressive cancers which appear confined to the prostate region, this is a great choice.