Radiotherapy

Evidence

GITSG

The GITSG trial (here) compared radiation alone (60 Gy) versus radiation and 5-fluorouracil chemotherapy. Radiation doses in the concurrent arm were 40 or 60 Gy. It recommended that:

  • Radiation alone was associated with a median survival of 5 1/2 months
  • Combination chemoradiotherapy was associated with a median survival of 10 months, with no difference between the 40 and 60 Gy treatments.

This trial forms the basis of concurrent chemoradiotherapy for pancreatic cancer in the adjuvant setting.

Controversy

EORTC

The 1999 EORTC gastrointestinal trial group (PubMed citation here; PubMed Central Full Text here) compared adjuvant concurrent radiochemotherapy with observation. It found that although radiotherapy was well tolerated, there was no significant benefit obtained in its use compared with observation.

  • 2 year survival was 30% in the treated group and 20% in the observed group; the results were not significant.

ESPAC

The 2004 ESPAC trial (PubMed citation here, or the full text here) recommends against radiation due to worse outcomes compared to chemotherapy alone.

  • Chemoradiotherapy alone consisted of 20 Gy in 10 fractions with concurrent 5-fluorouracil (bolus on the first three days of radiotherapy)
  • Chemotherapy alone consisted of 6 cycles of leucovorin / 5-fluorouracil
  • Chemoradiotherapy followed by chemotherapy consisted of the two schedules arranged sequentially

This study was criticised in America for poor quality control, and chemoradiotherapy remains the mainstay of treatment.


Dose

1.8 Gy per fraction is the usual recommended dose. Concurrent chemotherapy with 5-fluorouracil is required.
50.4 Gy / 28# with concurrent 5-fluorouracil is standard of care.
Escalation to 54 Gy / 30# should be considered in fit patients.
A shrinking field technique may be used:

  • Phase I - 45 Gy / 25#
  • Phase II - 5.4 Gy / 3 # (to reach 50.4 Gy total)
  • Phase II - 3.6 Gy / 2 # (to reach 54 Gy total)

Techniques

Volumes

RTOG 09

Organs at Risk

The pancreas lies in the retroperitoneum. It is surrounded by numerous critical structures, including:

  • The liver
  • The spleen
  • The kidneys
  • The stomach
  • The small bowel
  • The large bowel
  • The spinal cord

Dose to these organs should be reduced as much as practical; this usually necessitates conformal planning with contouring of organs at risk.

3D Conformal Radiotherapy

IMRT


Links