In the Clinic

On Cancer: Treating Prostate Cancer with a Missile-Like Delivery of High-Dose Radiation

By Esther Napolitano, BS, Science Writer/Editor  |  Wednesday, October 23, 2013
Pictured: Michael Zelefsky Radiation oncologist Michael Zelefsky delivers brachytherapy — the placement of radioactive seeds into the prostate gland — with the assistance of an intraoperative CT unit called the O-Arm, which gives real-time snapshots of the prostate.

Memorial Sloan Kettering has long been recognized as a pioneer in the treatment of cancer with radiation. The collaboration of radiation oncologists and medical physicists has produced the development and clinical implementation of new therapies that are “beyond the standard approaches and definitely not out of the textbook,” in the words of Radiation Oncology Department Chair Simon N. Powell.

Evolving technologies and novel enhancements, many of which were developed by Memorial Sloan Kettering medical physicists, have spurred a number of new clinical initiatives led by radiation oncologists investigating more-effective approaches. Memorial Sloan Kettering has particular expertise in the use of intensity-modulated radiation therapy (IMRT), which targets tumors with multiple beams at different angles and intensities.

The SHARP Advantage

Memorial Sloan Kettering’s extensive experience working with IMRT has served as an important foundation for the development of new approaches to treat prostate cancer. With the help of sophisticated image guidance and global positioning system (GPS) techniques, radiation oncologists are now able to offer prostate cancer patients a more focused approach to delivering higher doses of radiation more accurately and in less time than with IMRT.

Using a form of radiosurgery called stereotactic hypofractionated accelerated radiation to the prostate (SHARP), physicians can deliver ultrahigh doses of radiation in only five treatment sessions, compared with close to 50 sessions over ten weeks using the conventional approach.

GPS markers called ferromagnetic transponders are implanted by a urologist into the patient’s prostate gland. The beacons act as homing devices, sending out electromagnetic signals of the prostate’s exact location that can be used to guide the linear accelerator, which delivers high-energy radiation to the prostate over several minutes. If the prostate moves outside of a very tight margin, the radiation treatment can be stopped and adjustments made.

“This kind of missile technology helps us and our medical physics colleagues localize the target with an accuracy akin to the sharpness of a surgeon’s scalpel, sculpt a high dose of radiation around the prostate, and effectively minimize the amount of normal tissue that’s included in that margin,” says radiation oncologist Michael J. Zelefsky. “In this way, we can safely give the entire course of radiation in only five treatment sessions with fewer side effects.”

Memorial Sloan Kettering is the only hospital in Manhattan currently offering this treatment approach and one of only a few academic medical centers in the world doing it within the context of an ongoing clinical trial. Despite the application of high radiation doses, the more than 100 patients with disease confined to the prostate who have been treated with SHARP have tolerated the treatment well. After treatment, patients are closely followed with MRIs and a prostate biopsy.

“SHARP will likely replace the standard way of delivering external radiation therapy for prostate cancer if continued research and patient follow-up show that it is equally or more effective,” says Dr. Zelefsky.

Improving Brachytherapy with Intraoperative Image Guidance

Over the past 15 years, Memorial Sloan Kettering has established long-term success rates using brachytherapy — the placement of radioactive seeds into the prostate gland to deliver an extraordinarily high dose of radiation to the tumor.

Brachytherapy delivery has been improved by the incorporation of advanced imaging techniques that are commonly used for diagnostic procedures and treatment planning prior to treatment. In fact, it built the only state-of-the-art intraoperative imaging suite in the country dedicated solely to brachytherapy procedures.

One unique feature of the suite is a portable intraoperative CT unit called the O-Arm, which allows physicians to obtain real-time snapshots of the prostate that are fused with ultrasound images to target and confirm the accuracy of radioactive seed placement during the procedure. Memorial Sloan Kettering is currently the only center in the world routinely using this system during brachytherapy.

Marco Zaider, Head of Brachytherapy Physics, and Gikas S. Mageras, Chief of the Computer Service, led a team that developed a unique, patent-pending computer program that enhances the precision of the procedure by enabling physicians to receive instantaneous feedback about exactly where the seeds should be placed within the prostate gland and giving them the opportunity to make corrections on the spot. Being able to obtain and act on this information while a patient is asleep during the procedure in the operating room reduces the possibility that physicians will have to make adjustments later.

“Another advantage is that we can now safely re-treat patients with prostate tumors that have recurred years after treatment with other modalities by using this pinpointed seed implant approach, presenting a treatment option for these patients that didn’t exist before,” says Dr. Zelefsky, who is Chief of the Brachytherapy Service.

Memorial Sloan Kettering’s intraoperative imaging suite also offers MRI, which shows soft tissue differentiation, and PET/CT, which provides detailed anatomical images. Plans are under way to integrate these tools into a computer navigation system that could be used to further refine seed placement during brachytherapy. This unique combination of advanced imaging tools will enhance treatment planning and delivery as well as tumor assessment after treatment, allowing for more-adaptive therapy in which treatment changes can be made based upon tumor response.

“What makes the prostate program at Memorial Sloan Kettering unique is the availability of this comprehensive package of options we can offer our patients,” says Dr. Zelefsky. “Our expertise and this array of options at our disposal enable us to tailor radiation therapy based on the characteristics and location of the tumor, as well as important physical, emotional, and psychological factors that take the entire individual and his quality of life into account.”

This blog entry is part of a larger feature about advances in radiation oncology published in the October 2013 issue of Center News.

Comments

I have recently been diagnosed with prostate cancer. T2a, Gleason 4 +3, PSA 2.8
Ptrvious two yrs 2.0 and 2.2). I am 62 and healthy I work out three times a week and play golf 3-4 times. My parents are 93 and 92 and going strong. Is seed implantation an option for me? What would be my projected life expectancy with this procedure?

Gary, we are unable to answer specific medical questions on our blog. If you would like to make an appointment with a Memorial Sloan-Kettering physician, please call our Physician Referral Service at 800-525-2225 or go to http://www.mskcc.org/cancer-care/appointment. Thanks for your comment.

Gary, you may also wish to have a look at our prostate cancer nomograms. These are prediction tools that can be used to help you decide which treatment approaches may be right for you. Here's the link: http://www.mskcc.org/cancer-care/adult/prostate/prediction-tools. We wish you all the best!

I had HIFU Surgery 3 1/2 years ago and have recently been diagnosed with prostate cancer once again, either residual or recurring. We are discussing whether to have radiation or robotic surgery as our choice. Can SMART be used with only a tiny piece of the prostate left and how do I choose?

Gary, unfortunately we are unable to answer specific medical questions on our blog. If you would like to make an appointment with a Memorial Sloan-Kettering physician, please call our Physician Referral Service at 800-525-2225 or go to http://www.mskcc.org/cancer-care/appointment. Thanks for your comment.

i completed radiation therapy for prostate cancer on1/31/12,on 1/31/13 psa 0.09
however,on11/13/13 some22 months later psa is 3.1 has the cancer returned?

Dear John, unfortunately, this is not a question we can answer over our blog. If you would like to make an appointment with a Memorial Sloan-Kettering physician, please call our Physician Referral Service at 800-525-2225 during business hours. You can also go to http://www.mskcc.org/cancer-care/appointment to find out more about making an appointment.

ATT: MICHAEL ZELEFSKY
Michael,
Your work and that of your colleagues at Sloan continue to reassure me as a long-time PCa patient, having undergone 3-D Conformal EBRT there years ago.
Ben Schlossberg

Does Memorial Sloan-Kettering offer radiation therapy for PCa at any locations overseas?

Unfortunately, Memorial Sloan-Kettering does not have any overseas locations. If you are interested in making an appointment, you can contact our International Center at (1-212-639-4900) or go to http://www.mskcc.org/cancer-care/international-patients.

Thank you for your comment.

How is SHARP different from Cyberknife?

Dear Bill, we sent your inquiry to Dr. Zelefsky and he responded: "Cyberknife is a name of a company and the machine used to deliver radiation. SHARP delivers this kind of radiation from a high energy linear accelerator. The advantage of our SHARP program is that we routinely track the motion of the prostate during the actual treatment and can adjust the position of the beams even during the treatment as at times the prostate can have small shifts of its position. The Cyberknife system doesn't routinely do that." Thank you for your comment.

Does Dr. Zelefsky's current clinical study regarding the use of Viagra to mitigate the side effects of prostate radiation therapy include SHARP patients? (In Fort Wayne we use the term-Cyberknife Photon Beam Therapy.) Also, does he have any preliminary findings available?

Dear Sheldon, we sent your inquiry to Dr. Zelefsky and he responded: "It does not appear that the use of Viagra daily during the radiation treatment would influence or lower the side effects of radiation therapy. Our preliminary results of the study you refer to is a trial where patients were given Viagra on a daily basis to prevent the development of erectile dysfunction. It appears that at this time patients who took the drug on a daily basis had a lowered risk for losing their erections. We anticipate that the full results of this study will be published in the near future." Thank you for your comment.

Prior to this new treatment called SHARP, did MSK offer a high dose radiation treatment for PCa requiring only 5 sessions, even though it did not use the GPS technology? If so, about how long ago did that start?

Bill, we forwarded your question to Dr. Zelefsky, who said, "We began using the five-treatment hypofractionated short-course regimen at the same time as our using the GPS prostate tracking system. Prior to that we were essentially exclusively using the conventional regimens, which span for ten weeks." Thank you for your comment.

Is the best after-surgery Radiation treatment 7 days a week for duration of therapy?

Jay, unfortunately we are unable to answer specific medical questions on our blog. If you would like to make an appointment with a Memorial Sloan-Kettering physician, please call our Physician Referral Service at 800-525-2225 or go to http://www.mskcc.org/cancer-care/appointment. Thanks for your comment.

For patients with advanced PCa with metastasis outside the prostate into the spine it has been recommended that a course of IMRT be efficacious to improve the eventual localized urinary disease effects . Might Sharp be a modality in this circumstance ? Thank you

Edward, we are looking into this and will let you know when we have more information. Thank you for your comment.

Dear Edward, we sent your inquiry to Dr. Zelefsky and he responded: "Thank you for your comment and question. Our radiation oncologists generally consider in some cases where the disease spreads to the spine to use stereotactic radiosurgery which is a form of SHARP therapy. The results appear to be more effective than more protracted courses of lower-dose treatments."

Thank you for reaching out to us.

Thank you Dr Zelefsky for your reply , however , I was questioning the radiation technique to the prostate itself - not the metastatic lesions . Specifically the use of SHARP versus 9 weeks of IMRT - to potentially avoid the localized urinary obstructive symtoms near the later stages of the disease process .Thank You Sir

Dear Edward, SHARP has the advantage of enhanced accuracy and so far patients have tolerated it well. We continue to follow patients to gather longer-term data regarding side effects. We cannot answer personal medical questions on the blog, so if you are interested in a more-personalized assessment to see if SHARP is right for you, we would encourage you to make an appointment for a consultation with one of our specialists by calling our Physician Referral Service at 800-225-2225. Thank you.

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