Transcript Slide 1 - The Prostate Net

The Role of Radiation Therapy in the
Management of Prostate Cancer
Mark L. Merlin, M.D.
Radiotherapy Clinics of Georgia
7/14/2010
• Radiation oncology is a field of
medicine that specializes in the
destruction of cancer cells using
various forms of radiation
– Balance normal tissue damage versus
eradication of cancer
• Radiation therapy works by either
directly killing cancer cells or by
damaging their DNA
• Normal tissue cells have a mechanism
for repairing DNA damage
• Cancer cells have a diminished ability
to repair this sub lethal damage
Natural history
• If detected early, prostate
cancer remains confined to the
prostate or immediately
adjacent tissues
– Spread to surrounding
nerves / fatty tissues
– Spread to adjacent lymph
nodes
– Spread to distant sites such
as bone
Radiation versus Surgery
• Data is retrospective
• Patient selection varies
• Overall data does not suggest one option is better than
another
• Some clinical situations may benefit more from one type of
therapy
• Side effects vary significantly
• Patients should research all options
• Focus on cure rates, side effects, and quality of life issues
• Centers of excellence
Radiation therapy options
• External beam therapy with photons - IMRT
(Intensity Modulated Radiation Therapy)
• Brachytherapy
– Permanent or temporary seeds
• Brachytherapy / External beam therapy
• Particle therapy
– Protons, Neutrons
• Stereotactic radiation
– Cyberknife, Tomotherapy
External beam therapy
• Multiple photon beams aimed at a target
• Patient specific moving shields for normal
tissues
• IMRT – software planning based on CT scan
images
• Daily treatment
External beam therapy
• Photons enter through skin and are directed
at target
• Some exposure to surrounding tissue
• Improved imaging and computer software
Brachytherapy
• Radiation source is placed inside or next to the area
requiring treatment
• Needles are placed through skin of the perineum
• Radioactive seeds are implanted through needles
• Permanent seeds – Iodine, Palladium, Cesium
• Temporary seeds – Iridium
Brachytherapy
• Best used alone if the chance for
extracapsular spread is low
• Chance for extracapsular spread relies on
certain clinical factors:
– PSA
– Gleason score
– Number of positive biopsies
– Stage (findings on digital rectal exam)
– Presence of perineural invasion
Brachytherapy combined with
External Beam therapy
• Allows more intense radiation dose to
prostate through brachytherapy
• Allows treatment with external radiation
to encompass some areas around
prostate for potential spread
• Combination may overcome limits of
either modality on its own
Stereotactic Radiation
• Focused radiation beams targeting a well
defined tumor using extremely detailed
imaging scans
– Cyberknife
– Tomotherapy
• Cure rate data following
treatment is not available
due to short follow-up
Particle therapy
• Special case of external beam
radiation where the particles
are protons or heavier ions
• Dose increases while the
particle penetrates the tissue
up to a maximum that occurs
near the end of the particle’s
range
• The dose then drops to
almost zero
Proton beam therapy
 Loma Linda 2004 article
 1255 pts treated with protons for prostate cancer
 Overall cure rate 73%
 Massachusetts General 2008 article
 Recommended further study on protocol before rapid
adoption
 Cited tremendous increase in price for machines with no
proven benefit over current linear accelerators
 Protocols for dose, treatment setup, and parameters for
shielding uninvolved tissues remain in evolution
 Standard long term radiation effects on urinary and rectal
function do exist
Hormone therapy combined
with radiation
• Two large randomized studies have shown that patients with
locally advanced prostate cancer treated with standard
external beam therapy have higher cure rates if they also
receive testosterone suppression
• EORTC (2002) – GS 8-10 and T1/T2 or any T3/T4 pts
– RT alone vs RT + LHRH x 3 yrs
– 5 yr OS 62% vs 78%
• RTOG (2005) – T3 or N1
– RT alone vs. RT + LHRH x 28 months
– 10 yr absol surv 39% vs. 49%
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Hormone therapy side
effects
Hot flashes
Decrease in muscle tone
Weight gain
Impotence
Decreased libido
Fatigue
Emotional lability
Increased risk of cardiovascular death
Breast enlargement / tenderness
Radiation following radical
prostatectomy
• Following surgical removal of the prostate, a careful
pathological analysis is done
• Organ confined vs. not confined (seminal vesicle
involvement, capsule penetration, or margin
involvement)
• Patients with certain features have a higher risk of
cancer recurrence within the prostate bed
Radiation following radical
prostatectomy
• In the past, many patients and physicians have followed the
PSA level after surgery
• Recent randomized trials suggest that those patients with
high-risk features should be evaluated for immediate
radiation to the prostate bed
• Improved survival rates have been found with immediate vs.
delayed radiation
– 10 yr OS 71% vs. 61%
• Standard of care is to evaluate all high risk patients following
surgery for possible radiation therapy
Radiation side effects
• Acute effects (during treatment)
– Urinary
– Rectal
– General
• Late effects (months – years after treatment)
– Urinary / Sexual
– Rectal
– Secondary Cancer
Get educated!
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Do your own research
Talk with friends and family
Use the internet
Get second opinions
Read prostate books
literature
• Organizations such as The Prostate Net help to
raise public awareness and promote education
of available resources
• Evidence based medicine
• Centers of excellence with database of prior
patients
Any Questions?
Contact Information
Mark L. Merlin, M.D.
Radiation Oncologist
Phone: 404-633-5606 Ext. 180
Email:
[email protected]