Radiotherapy in the Treatment of Cancer

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Radiotherapy in the Treatment of Cancer

• Darin Gopaul MD FRCPC
• Grand River Regional Cancer Centre

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Introduction
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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"

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Marie Curie (1867 1934)

• Born in Poland
• University of Paris age 24
• Discovered Radium 1898
• t1/2 1602 years

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Intracavitary Brachytherapy
Fletcher-Suit applicator
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Interstitial Brachytherapy
Radium Needles
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Prostate Brachytherapy
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Prostate Brachytherapy
Iodine 125 t ½ 60 days Gamma emitter Energy
35 kV
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Free-hand implant technique
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Prostate Brachytherapy
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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

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Prostate Brachytherapy

• Results
• Gleason 2-4 86
• Gleason 5-6 63
• PSA lt 4 93-100
• PSA 4 -10 70-86
• T1c 90-94 T2a 70-74

5 year actuarial biochemical freedom from failure
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Prostate Brachytherapy

• Patient Selection
• PSA lt 10
• Gleason score 2 6
• T1c T2a

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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

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External Beam Radiotherapy
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1951 First Cobalt machine

• Saskatoon, Saskatchewan
• London, Ontario
• Co 60
• t ½ 5.26 years
• Gamma emitter
• Energy 1.25 MV

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Cobalt- 60
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Definition

• Gray
• A unit of absorbed radiation equal to the dose
  of one joule of energy absorbed per kilogram of
  matter, or 100 rads.

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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

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Palliative Radiotherapy
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Palliative radiotherapy

• Relief of symptoms (bone met)
• Prevention of symptoms or morbidity
• Improve survival duration (brain mets)

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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

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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)

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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?

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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

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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

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Palliative Radiotherapy Lung Ca

• Stage III Not a candidate for radical
  radiotherapy
• Poor PS
• Significant weight loss
• Large tumor gt 7cm
• Inadequate pulmonary reserve for radical
  radiotherapy
• Stage IV metastatic

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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

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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

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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

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Co 60 Radiosurgery Gamma Knife
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Co 60 Radiosurgery Gamma Knife

• Invented 1950s
• 201 Cobalt sources
• Precision mounted
• 4mm 4cm target
• Rigid Immobilization

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Gamma Knife
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Linear Accelerator
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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

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Linac Radiosurgery X Knife

• High energy beam
• 1 moving source
• 5mm 4cm target

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Linac Radiosurgery X Knife

• Advantages
• Allows multiple fractions
• More widely available
• Linac has other uses

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Cranial Radiosurgery

• Indications
• Solitary Brain Met on MRI
• lt 4 cm maximal dimension
• 1- 3 Recurrent post Whole Brain Rads
• Good Performance Status (KPS gt 70)
• Limited or Controlled Extracranial Disease

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Adjuvant Radiotherapy
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Definition

• Adjuvant Therapy
• Post-operative treatment in the absence of
  demonstrable residual disease, to reduce the
  possibility of recurrence.

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Adjuvant radiotherapy Breast cancer

• Breast conservation
• Post mastectomy (loco-regional)

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Breast Conservation

• No difference in OS
• LR uncommon post adjuvant XRT
• LR can be salvaged with further surgery
• BCS Radiotherapy Mastectomy

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Breast Tangents
Computer assisted radiation planning
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Adjuvant radiotherapy Breast cancer

• Reducing treatment duration (OCOG study)
• 42.5 Gy in 16 vs 50 Gy in 25
• No difference in LR control
• No difference in cosmesis

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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

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Postmastectomy Radiotherapy

• Standard for High Risk disease
• Tumor gt 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

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Postmastectomy Radiotherapy

• Intermediate Risk disease
• T2 tumor with multiple adverse features
• High grade, LVI, ER-
• 1-3 lymph nodes
• Age lt 45 years
• LRR 10 -18 postmastectomy
• LRR 5 post Locoregional radiotherapy

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3D Conformal Radiotherapy
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3D Conformal Radiotherapy

• Acquire 3D spacial data
• Radiation Planning in 3D
• Deliver Radiation in 3D

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CT Simulator
Couch
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MRI-CT Fusion (Co-Registration)

• MRI
• Excellent soft tissue contrast allows better
  differentiation between normal tissues and many
  tumors
• Disadvantages
• Susceptible to spatial distortions

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Treatment Planning
Beam Placement
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Multileaf Collimator (MLC)
No more lead blocks!
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Prostate Radiotherapy
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Prostate 3D Planning
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Shaping the beam with MLC - prostate
AP View
Lateral View
Beams Eye View (BEV)
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Verification - EPID images
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Increasing Conformality
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Advantages

• Enhanced Normal Tissue Sparing
• Reduces side effects
• Dose Escalation Improves Cure Rate
• Higher Dose per Fraction
• Reduce Number of fractions
• Reduce Treatment Duration

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The Future
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Targeting System
X-ray sources
Manipulator
Synchrony camera
Linear accelerator
Robotic Delivery System
Image detectors
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Thank-you!