Early stage colorectal cancer is treated with surgery, while more advanced stages receive surgery plus chemotherapy or radiation and chemotherapy. Metastatic or recurrent disease is treated with chemotherapy, targeted therapy, and sometimes radiation or surgery. Radiation is commonly used to treat rectal cancer before or after surgery to reduce the risk of local recurrence. It can safely expand the surgical resection area and increase the chance of sphincter preservation. Radiation techniques use imaging like CT and PET scans to precisely target the radiation dose to areas at risk while minimizing side effects. Radiation can also effectively palliate symptoms from recurrent or metastatic colorectal cancer.

1. Radiation and Colorectal
Cancer
Robert Miller MD
www.aboutcancer.com

2. NCCN.org

4. Treatment of colorectal
cancer
• Early stages are treated with surgery
• More advanced stages have surgery followed
by chemotherapy (colon) or radiation and
chemotherapy prior to surgery (rectum)
• Metastatic or recurrent disease treated with
chemotherapy or targeted therapy and
possibly radiation, some patients benefit from
surgical resection or RF ablation

5. Workup or Evaluation Prior to Deciding
on Treatment for Colon Cancer

6. Workup or Evaluation Prior to Deciding
on Treatment for Rectal Cancer

7. Accuracy of Imaging in Staging
Rectal Cancer
Site Ultrasound CT MRI
Tumor 80-95% 65-75% 75-85%
Nodes 70-75% 55-65% 60-65%

9. T2 T3
Nodes
Transrectal Endoscopic Ultrasound (TEUS)

10. Radiation can safely cover the sites
where rectal cancer is most likely
to recur
3D reconstruction of sites of relapse in patients with rectal cancer

11. Radiation can safely expand the
‘surgical resection’ volume

12. surgery
Radiation
field
Radiation can safely expand the
‘surgical resection’ volume

13. Radiation Technique
CT scan is obtained at the time of
simulation
CT images are then imported
into the treatment planning
computer

14. In the simulation
process the CT
and PET scan
images are used
to create a
computer plan

15. Imaging rectal cancer radiation fields
Portal image (x-ray
image showing the
area of radiation (light
blue)
Computer generated
radiation target (dark blue)

16. Sites of Relapse in Red
Based on the location of
the most common sites for
a relapse after surgery the
radiation field in green
should be large enough to
cover these areas

17. Radiation
Targets or
Fields

18. Radiation Fields
• Include the tumor and tumor bed with
a 2 to 5cm margin
• Include the presacral nodes and internal iliac nodes
• Include the external iliac nodes if T4 involving
anterior structures
• Top: Usually L5-S1 or 1.5cm above sacral
promontory and the bottom 4 to 5cm below edge of
tumor
• Posterior 1cm behind the sacrum and anterior the
post wall of the vagina or a large portion of the
prostate

23. Radiation dose clouds are tailored to the
areas that are at risk

24. Computer generated images and the
size of the radiation cloud around these
structures

25. CT and
PET scan
for man
with
locally
advanced
rectal
cancer

26. Woman with
low rectal
cancer, on
ultrasound
the stage
was T3N1

27. PET
Scans
Early
Rectal
Cancer
Locally
Advanced
Rectal
Cancer
into lymph
nodes

28. Using PET Scan to identify site of rectal
cancer
cance
r
rectum
prostat
e
pubic
bone
bladder
small
bowel

29. Computer generated images to match
the PET scan

30. PET scan images are used to target the
areas that need radiation

31. Original PET scan showing area of
cancer
Computer generated images with
radiation

32. PET
scan
images
are used
to target
the areas
that need
radiation

33. Radiation Dose Fields Surround
the Cancer

34. PET Scan will also show if
the cancer has spread
elsewhere in the body such
as the lymph nodes or liver
This case show areas of
liver metastases so the
patient would be classified
as having stage IV rectal
cancer and would need
chemotherapy

35. Techniques to minimize radiation side effects

36. Benefit of Combining chemoradiation
with surgery for rectal cancer
• Will lower the risk of a local
recurrence in the pelvic region and
improve survival
• If given prior to surgery may help the
surgeon avoid a permanent
colostomy
• If given before surgery may be less
complications than if given after
surgery

37. Improved Outcome after Surgery by
Adding Chemoradiation
Gastrointestinal Tumor Study Group
N Engl J Med 1985; 312:1465-1472

38. German Trial of PreOp or PostOp
Chemoradiation for Rectal Cancer
NEJM 2004;351:1731
Outcome PreOp PostOp
Survival 76% 74%
Local Relapse 6% 13%
Complication 27% 40%

39. Chemo-Radiation will often shrink the
cancer making surgery easier

40. Chemo-Radiation will often shrink the
cancer making surgery easier

41. Appearance of
advanced rectal cancer
at colonoscopy before
chemoradiation
Appearance after
PreOp Chemoradiation for
Locally Advanced Rectal Cancer

42. PreOp Chemoradiation for Locally Advanced
Rectal Cancer and Sphincter Preservation
Shrink the size or bulk
of the tumor A to B to
make surgery easier
Shrink the
location away
from the sphincter
making surgery
possible

43. Benefits of preOp chemoradiation for
Rectal Cancer in Avoiding a
Permanent Colostomy
In series where patients were expected
to require a colostomy, after preOp
therapy the number who were able to
avoid a permanent colostomy (sphincter
preservation) in such reports ranges
from 39 to 94 percent, averaging 67
percent

44. Typical Course of Preoperative radiation
• Daily radiation (Monday through Friday) 5 days a week for 28
treatments (so 5 and half weeks
• Treatments generally take about 10 minutes
• Radiation is combined with daily chemotherapy (usually continuous
IV infusion of 5FU)
• Side effects typically show up after the second week and fade away
starting a week or two after completion
• Surgery is generally scheduled 3 to 6 weeks after completing the
radiation
• Further chemotherapy is often given after surgery

45. Side Effects of Pelvic Radiation
Radiation fields
Radiation may hit the small
bowel causing some
cramps, diarrhea and fatigue
Fatigue, diarrhea, loss of appetite and rectal
irritation are very common during the combined
chemoradiation period

46. Side Effects of Pelvic Radiation
Radiation fields
Radiation may hit the
bladder and rectum causing
urinary burning or frequency
and rectal irritation
In pre-menopausal women, radiation is likely to effect
ovarian function and should not be used if the woman is
pregnant

47. Palliative radiation
 Local pelvic relapses
 Liver metastases
 Distant metastases

48. Palliating Pelvic Relapses
 Pain response rates in 64 – 85%
range
 One series complete relief was
bleeding (100%) pain (65%) mass
24%

49. Recurrent Colon Cancer with
Unresectable Mesenteric Mass

50. Recurrent Mass surrounded
by loops of normal bowel

51. Combine a CT scan and linear accelerator to ultimate in
targeting (IGRT) and ultimate in delivery (dynamic, helical
IMRT) ability to daily adjust the beam (ART or adaptive
radiotherapy)
Image Guided (IGRT) and Intensity
Modulated Radiation Therapy (IMRT

52. Using image guided IMRT can better target the
cancer and limit the dose to normal structures

53. Clinical outcomes using stereotactic body
radiotherapy for abdominopelvic tumors.
Department of Radiation Oncology, Mayo
Clinic
Tumor responses of the 48 target were
complete response in 18 lesions (36%), partial
response in 12 lesions (24%), stable disease
in 12 lesions (24%), and progressive disease
in 6 lesions (12%).
So 60% response
Am J Clin Oncol. 2012 Dec;35(6):537-42.

54. Low Dose Radiation for Liver
Metastases (40 – 80%)

55. Radiosurgery for Cancer

56. Radiosurgery for Liver Mets

57. Radiosurgery for Liver Mets

58. A phase I/II dose-escalation trial of
Cyberknife radiation for control of primary
or metastatic liver disease
Early toxicity has been mild with 3 patients (13%) experiencing grade 2 or
greater toxicity. In the 21 patients with >3 month follow-up, 3 (14%) have
experienced a late toxicity. There have been 6 local recurrences. The lesion
local recurrence rate is 17% and the patient local recurrence rate is 25%.
Mean time to recurrence was 8.4 months.
Conclusion: Cyberknife radiation can be delivered safely in doses up to 30
Gy in a single fraction. Accrual of long-term local control and toxicity data is
ongoing.

59. Whole brain radiation

60. Typical response for whole brain radiation

61. Radiosurgery for Brain Metastases
from colorectal Cancer
152 patients with 616 tumors for metastatic brain
tumors from colorectal cancer
The primary tumors were located in the colon in 88
patients and the rectum in 64.
The local tumor growth control rate, based on MR
imaging, was 91.2%
Cause of death was systemic in 90% and brain 10%
J Neurosurg. 2011 Mar;114(3):782-9

62. Bone Metastases and Radiation
Before XRT 3 months after XRT

63. Radiation and Colorectal
Cancer
Robert Miller MD
www.aboutcancer.com