Radiotherapy in the Treatment
of Cancer
Darin Gopaul MD FRCPC
Grand River Regional Cancer Centre
Introduction
POISONED! -- as They Chatted Merrily at Their Work
Painting the Luminous
Numbers on Watches, the
Radium Accumulated in Their
Bodies, and Without Warning
Began to Bombard and
Destroy Teeth, Jaws and
Finger Bones. Marking
Fifty Young Factory Girls for
Painful, Lingering,
But Inevitable Death"
Marie Curie (1867 – 1934)
Born in Poland
University of Paris age 24
Discovered Radium 1898
t1/2 = 1602 years
Intracavitary
Brachytherapy
Fletcher-Suit applicator
Interstitial
Brachytherapy
Radium Needles
Prostate Brachytherapy
Prostate Brachytherapy
Iodine 125
t ½ = 60 days
Gamma emitter
Energy 35 kV
Free-hand implant technique
Prostate Brachytherapy
Prostate Brachytherapy
Adverse effects
• Urinary symptoms common
• Dysuria, frequency, urgency, nocturia
• Acute urinary retention 1-14%
• Urinary incontinence 5- 6%
• Proctitis 1-3%
But…
• Sexual potency preserved 86 -96%
• At 2 – 3 years
Prostate Brachytherapy
Results:
Gleason 2-4
Gleason 5-6
86%
63%
PSA < 4
PSA 4 -10
93-100%
70-86%
T1c
T2a
90-94%
70-74%
5 year actuarial biochemical freedom from failure
Prostate Brachytherapy
Patient Selection
• PSA < 10
• Gleason score 2 – 6
• T1c – T2a
Prostate Brachytherapy
• Advantages over standard EBRT:
–
–
–
–
Does not require 6 - 7 weeks of daily fractionated treatments
Less long-term toxicity due to radiation of adjacent organs
Lower incidence of erectile dysfunction
Day surgery procedure requiring only a single visit
• Disadvantages compared to EBRT:
– More susceptible to dosimetry errors in delivery of radiation
– Requires a general / spinal anesthetic for implant
– Higher incidence of voiding dysfunction at time and after
treatment
– Requires precautions regarding radiation exposure to family
and friends
– Only proven for low-stage and low-grade disease
External Beam Radiotherapy
1951 – First Cobalt machine
• Saskatoon, Saskatchewan
• London, Ontario
• Co 60
– t ½ = 5.26 years
– Gamma emitter
– Energy 1.25 MV
Cobalt- 60
Definition
Gray:
A unit of absorbed radiation equal to the
dose of one joule of energy absorbed per
kilogram of matter, or 100 rads.
Typical doses
Palliative therapy
8 Gy in 1 fraction
20 Gy in 5 fractions
Adjuvant therapy
42.5 Gy in 16
50 Gy in 25
Radical Doses
60 Gy in 30
78 Gy in 39
Palliative Radiotherapy
Palliative radiotherapy
• Relief of symptoms (bone met)
• Prevention of symptoms or morbidity
• Improve survival duration (brain mets)
Case 1 – Palliative Radiotherapy
58 yo female with a history of metastatic breast ca.
Has had increasing back pain for 6 months. Bone
scan showed uptake (metastasis) at T5. No evidence
of visceral mets. Pain not well controlled with
narcotics (limited by side effects)
Pain reproduced on palpation of T5
Case 1 – Palliative Radiotherapy
Treated with palliative radiotherapy from T3 – T7
inclusive with 30Gy in 10 fractions over 2 weeks.
Possible side effects:
- skin dryness
- skin erythema
- odynophagia (radiation esophagitis)
Case 1 – Palliative Radiotherapy
Treated with palliative radiotherapy from T3 – T7
inclusive with 30Gy in 10 fractions over 2 weeks.
Possible side effects:
- skin dryness
- skin erythema
- odynophagia (radiation esophagitis)
Pain relief within 3-4 weeks
Prevention of spinal cord compression?
Skin Care Recommendations
Prevention
- Wash daily with mild, non-scented pH balanced soap
- Use of hand for washing the area, pat dry
- No new creams or oils in the treatment area
Treatment
- Asymptomatic erythema : no treatment
- Dry / itchy skin: aqueous cream (glaxal base, biafine)
- Red/ burning skin: 1% hydrocotisone cream
- Moist desquamation : Flamazine Cream +/- dressing
Case 2 – Palliative Radiotherapy
59 yo male smoker presenting with SOB, cough
and chest discomfort. No hemoptysis. Anorexia,
fatigue and a 30 lb weight loss.
CT Chest/abdomen, CT Brain, Bone scan
demonstrate 14cm lung mass invading into the
mediastinum (unresectable) but no mets.
PFTs demonstrate FEV1 0.8L and DLCO 36%
Palliative Radiotherapy – Lung Ca
• Stage III : Not a candidate for radical radiotherapy
– Poor PS
– Significant weight loss
– Large tumor > 7cm
– Inadequate pulmonary reserve for radical
radiotherapy
• Stage IV : metastatic
Palliative Radiotherapy – Lung Ca
Goals
• Symptom Control
– Cough
– Hemoptysis
– Chest Pain
• Delay intrathoracic progression
– Prevent lung collapse
– Prevent SVC
Aim is Quality of life not Quantity of life
Case 3 – Palliative Radiotherapy
• 42 yo female T2N1 NSCLCa, treated with
surgery. 8 months later presented with a
seziure, CT scan demonstrates multiple (4
brain mets)
• Treated with Whole Brain Radiotherapy
with clinical/radiologic response
Case 3 – Palliative Radiotherapy
• 8 months post Whole Brain XRT, presents
with clinical/ radiologic progression.
Options?
- Steroids (no response)
- Surgery (not for multiple lesions)
- Radiotherapy (already treated)
- Radiosurgery
Co 60 Radiosurgery – “Gamma Knife”
“Co 60 Radiosurgery – “Gamma Knife”
• Invented 1950’s
• 201 Cobalt sources
• Precision mounted
• 4mm – 4cm target
• Rigid Immobilization
Gamma Knife
Linear Accelerator
Linear Accelerator
• X-rays
• Higher energy (4 - 18Mv)
– compared to Gamma rays (1.25 Mv)
• Higher energy means
– More penetrating beam
– Treat deeper tumors
– Enhanced skin sparing
Linac Radiosurgery – “X Knife”
• High energy beam
• 1 moving source
• 5mm – 4cm target
Linac Radiosurgery – “X Knife”
Advantages
• Allows multiple fractions
• More widely available
• Linac has other uses
Cranial Radiosurgery
Indications
• Solitary Brain Met on MRI
• < 4 cm maximal dimension
• 1- 3 Recurrent post Whole Brain Rads
• Good Performance Status (KPS > 70%)
• Limited or Controlled Extracranial Disease
Adjuvant Radiotherapy
Definition
Adjuvant Therapy:
Post-operative treatment in the absence of
demonstrable residual disease, to reduce
the possibility of recurrence.
Adjuvant radiotherapy – Breast cancer
• Breast conservation
• Post mastectomy (loco-regional)
Breast Conservation
• No difference in OS
• LR uncommon post adjuvant XRT
• LR can be salvaged with further surgery
BCS + Radiotherapy = Mastectomy
Breast Tangents
Computer assisted radiation planning
Adjuvant radiotherapy – Breast cancer
Reducing treatment duration (OCOG study)
• 42.5 Gy in 16
vs
• No difference in LR control
• No difference in cosmesis
50 Gy in 25
Adjuvant radiotherapy – Breast cancer
42.5 Gy in 16 fractions now standard
•
Not for very large Breast volumes
•
3-5 “boost” treatments to the tumor bed
• Close or focal positive margins
• Premenopausal status
Postmastectomy Radiotherapy
Standard for High Risk disease
• Tumor > 5cm (T3)
• Tumor involves skin or chest wall (T4)
• 4 or more lymph nodes
– LRR 25-30% postmastectomy
– LRR 5- 10% post Locoregional radiotherapy
– OS improves 5%
Postmastectomy Radiotherapy
Intermediate Risk disease
– T2 tumor with multiple adverse features
– High grade, LVI+, ER-
– 1-3 lymph nodes
– Age < 45 years
– LRR 10 -18% postmastectomy
– LRR 5% post Locoregional radiotherapy
3D Conformal Radiotherapy
3D Conformal Radiotherapy
• Acquire 3D spacial data
• Radiation Planning in 3D
• Deliver Radiation in 3D
CT Simulator
Couch
MRI-CT Fusion (Co-Registration)
 MRI
 Excellent soft tissue
contrast allows
better differentiation
between normal
tissues and many
tumors
 Disadvantages:

Susceptible to spatial
distortions
Treatment Planning
Beam
Placement
Multileaf Collimator (MLC)
No more
lead blocks!
Prostate Radiotherapy
Prostate 3D Planning
Shaping the beam with MLC - prostate
AP View
Lateral View
Beam’s Eye View (BEV)
Verification - EPID images
Increasing Conformality
Advantages
• Enhanced Normal Tissue Sparing
• Reduces side effects
• Dose Escalation Improves Cure Rate
• Higher Dose per Fraction
• Reduce Number of fractions
• Reduce Treatment Duration
The Future
Targeting System
X-ray sources
Manipulator
Synchrony™
camera
Linear
accelerator
Robotic Delivery System
Image
detectors
Thank-you!