Radiotherapy For Colorectal Cancer

D R . D E W I S Y A F R I Y E T T I S O E I S M A R Z A I N I , S P R A D ( K ) O N K . R A D

D E P A R T M E N T O F R A D I O T H E R A P Y ,

D H A R M A I S N A T I O N A L C A N C E R C E N T E R

RADIOTHERAPY FOR COLORECTAL CANCER

COLORECTAL CANCER

The 3rd highest cancer in the world

Age-standardized incidence rate in Indonesia per 100,000 population (GLOBOCAN 2008):

19.1 for men

15.6 for women

MAJOR HEALTH PROBLEM

INDICATION FOR RADIOTHERAPY

Neoadjuvant – given preoperatively to patients with tumor invading outside the rectum or regional lymph nodes;

Adjuvant– given postoperatively to T3 / T4 orDuke’s B /C) tumors;

Palliative – given to advanced, unresectable tumors to reduce tumor burden and relieve symptoms (pain).

Goals of Radiation Therapy

Curative intent reduce recurrence and prolong survival Radiotherapy alone

Chemoradiation

Adjuvant radiation

Trimodality therapy

Palliation Relieve pain

Metastatic sites

Radiation Approach

External radiation: Pre- or post operative

With or without concurrent chemotherapy

Internal radiation or brachytherapy

External Beam Irradiation

Dual-energy linear accelerators generate: Low energy megavoltage x-rays (4-6 MeV)

High energy x-rays (15-20 MeV)

Photon energy

Particle Radiation (electrons, protons, neutrons)

Whole pelvic radiation

25 x 2 Gy

CT Simulator

Position

Simulation

Supine vs Prone

Supine vs. Prone + belly board

Median reduction of exposed volume small bowel – 54 % & Bladder – 62 %

Median dose to small bowel – 24 Gy Supine & 15 Gy - Prone + Belly board

Koebl et al - IJROBP 1999;45:1193-1198

Beam arrangements

AP-PA

3-field (PA + Bilateral)

4-field (AP-PA+ BL) - Ant Extension

Contouring

PLANNING RADIASI

Standard external RT: posteroanterior and laterals in prone position.

Plan Evaluation 3F W/O Wedge

Plan Evaluation

EXTERNAL RADIATION

Rectal IMRT

Limited data

Dosimetric studies favorable: Nuytens (2004)

Duthoy (2004)

Aristu (2005)

Guerrero-Urbano (2006)

Only 1 outcome study

Aritsu (2005) Spain: Phase I dose escalation study

37.5 Gy 42.5 Gy 47.5 Gy

In 19 fractions (preoperative)

No grade > 3 toxicity

Excellent pathologic response

85% down-stage

IMRT

Axial image displaying seven-beam intensity-modulated RT plan for postoperative patient to spare small bowel and femoral heads.

Brachytherapy

Radioactive source in direct contact with tumor Interstitial implants, intracavitary implants or surface molds

Greater deliverable dose

Continuous low dose rate

Advantage for hypoxic or slow proliferators

Shorter treatment times

BRACHYTHERAPY

Endorectal brachytherapy with fiducial markers (arrows) placed endoscopically to delineate the extent of tumor.

HIGH DOSE RATE BRACHYTHERAPY

Novi Sad rectal applicator

High dose rate rectal applicator after insertion.

flexible rectal applicator for high dose rate brachytherapy.

BRACHYTHERAPY

Sagittal plane dose distribution using the endorectal brachytherapy treatment technique.

Complications

Acute Effects Diarrhea

Nausea

Abdominal dyscomfort

Fatigue

Late Effects: Urinary incontinence

Fecal incontinence

Sexual dysfunction , erectile dysfunction

Follow-Up

During radiation: every week

After radiation: 2 weeks after radiation

1.5 -2 months afater radiation

Every 3 months for 2 years

Every 6 months for the next 2 years

Annualy thereafter

Evaluation: History including radiation side effects, clinical examination,

rectoscopy, blood test, imaging for suspected recurrence (CT scan or MRI).

Thank You

Mount Merapi