Uses of Radiation Therapy in Cancer Treatment

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!