PET Scans for Staging Colorectal Cancer

PET Scans for Colorectal Cancer Staging

Understanding the Role of PET Scans

PET (Positron Emission Tomography) scans are a common diagnostic tool used to stage colorectal cancer. Staging is the process of determining how far the cancer has spread beyond the colon. If you’ve already undergone blood tests, imaging scans, or biopsies, a PET scan may be recommended next to evaluate whether the cancer has metastasized (spread) to other areas of the body.

Unlike diagnostic tests that detect tumors inside the colon, PET scans provide insight into the presence of cancerous cells elsewhere in the body. This whole-body view helps doctors form an effective treatment plan.

Why PET Scans Are Used

Although PET scans can help diagnose other diseases involving the brain and heart, they are especially valuable for identifying cancer recurrence or metastasis. Often, PET scans are paired with CT (Computed Tomography) scans to provide highly detailed images that reveal potential cancerous activity throughout the body.

How PET Scans Work

Before your scan, a small dose of a radiotracer known as fluorodeoxyglucose (FDG) is injected into a vein. FDG is a radioactive form of sugar that cancer cells absorb more quickly than healthy ones. After about an hour, the tracer has traveled throughout your body, allowing the PET scanner to capture detailed 3D images of areas with increased metabolic activity—typically cancerous tissue.

Preparing for a PET Scan

Your healthcare provider will give you preparation instructions ahead of time. These might include:

• Wearing comfortable clothing

• Sharing a list of any medications, supplements, or herbal remedies you take

• Fasting for 4–6 hours prior to the scan

What to Expect During the Procedure

Once at the clinic or imaging center, you may be asked to change into a hospital gown. A technician will start an IV to administer the FDG tracer. After the injection, you’ll wait in a designated area for up to an hour as the tracer spreads throughout your body.

The scan itself involves lying flat on a narrow table that slides into the PET scanner, a tube-shaped machine. The scan can take up to an hour, and it’s important to remain still throughout. You’ll be able to communicate with the technician via an intercom during the process in case you feel discomfort.

What the Scan Will Reveal

The PET scan highlights areas of elevated glucose uptake—commonly seen in cancer cells, inflammation, and infections. These “hot spots” help your healthcare provider assess the extent of the disease and decide on next steps, whether it’s surgery, chemotherapy, or additional tests.

Post-Scan Information

You won’t be radioactive after the scan. The amount of tracer used is minimal and exits the body naturally, usually within a day. Drinking plenty of water afterward helps flush it out more quickly.

Results typically aren’t available immediately. A radiologist or nuclear medicine specialist will analyze the images and send a report to your doctor, who will share the results with you within 2 to 3 days.

Who Should Avoid PET Scans?

PET scans may not be suitable for everyone. Talk to your healthcare provider if you are:

• Pregnant or may be pregnant

• Breastfeeding

• Claustrophobic

• Unable to lie still or flat for an extended period

• Diabetic or have blood sugar concerns

• Allergic to contrast agents or injections

Your doctor will advise if a PET scan is appropriate or if another test, such as an MRI or biopsy, would be better.

What Is Colorectal Cancer?

Colorectal cancer starts in the colon or rectum and can grow to affect nearby or distant organs. It typically begins as small, benign clumps of cells called polyps, which can become cancerous over time. Early detection and accurate staging are key to successful treatment outcomes.

Frequently Asked Questions

What Does a PET Scan Show for Colorectal Cancer?

A PET scan highlights areas of abnormal metabolic activity, helping doctors locate cancer that has spread beyond the colon or identify possible recurrences.

How Soon Will I Get My PET Scan Results?

Results are usually available within 2 to 3 business days after the scan is interpreted by a radiologist.

Key Takeaways

• PET scans are vital for staging colorectal cancer and determining whether it has spread.

• They work by detecting areas with high glucose uptake, often associated with cancer ce