Radiation and Colorectal Cancer

Robert Miller MDwww.aboutcancer.com

NCCN.org

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

Workup or Evaluation Prior to Deciding on Treatment for Colon Cancer

Workup or Evaluation Prior to Deciding on Treatment for Rectal Cancer

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%

T2 T3

Nodes

Transrectal Endoscopic Ultrasound (TEUS)

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

Radiation can safely expand the ‘surgical resection’ volume

surgery

Radiationfield

Radiation can safely expand the ‘surgical resection’ volume

Radiation Technique

CT scan is obtained at the time of simulation

CT images are then imported into the treatment planning computer

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

Imaging rectal cancer radiation fields

Portal image (x-ray image showing the area of radiation (light blue)

Computer generated radiation target (dark blue)

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

Radiation Targets or Fields

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

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

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

CT and PET scan for man with locally advanced rectal cancer

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

PET Scans

Early Rectal Cancer

Locally Advanced Rectal Cancer into lymph nodes

Using PET Scan to identify site of rectal cancer

cancer

rectum

prostate

pubic bone

bladder

small bowel

Computer generated images to match the PET scan

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

Original PET scan showing area of cancer

Computer generated images with radiation

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

Radiation Dose Fields Surround the Cancer

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

Techniques to minimize radiation side effects

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

Improved Outcome after Surgery by Adding Chemoradiation

Gastrointestinal Tumor Study GroupN Engl J Med 1985; 312:1465-1472

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%

Chemo-Radiation will often shrink the cancer making surgery easier

Chemo-Radiation will often shrink the cancer making surgery easier

Appearance of advanced rectal cancer at colonoscopy before chemoradiation

Appearance after

PreOp Chemoradiation for Locally Advanced Rectal Cancer

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

Benefits of preOp chemoradiation for Rectal Cancer in Avoiding a Permanent ColostomyIn 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 

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

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

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

Palliative radiationLocal pelvic relapsesLiver metastasesDistant metastases

Palliating Pelvic Relapses

Pain response rates in 64 – 85% range

One series complete relief was bleeding (100%) pain (65%) mass 24%

Recurrent Colon Cancer with Unresectable Mesenteric Mass

Recurrent Mass surrounded by loops of normal bowel

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

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

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.

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

Radiosurgery for Cancer

Radiosurgery for Liver Mets

Radiosurgery for Liver Mets

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.

Whole brain radiation

Typical response for whole brain radiation

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

Bone Metastases and Radiation

Before XRT 3 months after XRT

Radiation and Colorectal Cancer

Robert Miller MDwww.aboutcancer.com