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Biomarker testing procedure
Colorectal Cancer:
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Treatment guide:
Recovery time
Colonoscopy preparation typically requires: eliminating high fiber foods 3 to 5 days earlier starting on a clear liquid diet the day before starting your prescription bowel prep laxative as directed stopping all food and drinks a few hours before the procedure (your doctor will specify the time)
How to prepare for each test
Tumor biopsies are more invasive than liquid biopsies. They often involve a colonoscopy, where a doctor uses a lighted scope inserted through the rectum to guide tissue sampling. In some cases, doctors remove tissue surgically (excisional biopsy) while you’re under anesthesia. Tumor biopsies are done at the time of diagnosis to determine the cancer’s type and grade. They’re repeated if the treatment stops working. Liquid biopsies only require a blood draw. They can be performed more frequently to help monitor treatment changes.
Differences
A tumor biopsy uses a tissue sample from a cancerous tumor to determine the cancer type and identify specific DNA abnormalities. Tumor biopsies can be performed using a needle, or doctors can surgically remove some or all of the cancer for testing. Liquid biopsy is a blood test that captures atypical DNA shed into the blood from cancer cells. While tumor biopsy samples only one area of the tumor, liquid biopsy includes all DNA from the cancer and any sites it has spread to, without needing to test each site separately.
Tumor biopsy vs. liquid biopsy
Liquid biopsies have almost no downtime. The phlebotomist may ask you to sit for 15 minutes or so to keep the self-adhesive bandage or tape on the site where the blood was drawn. Recovery from an excisional biopsy may take longer. Depending on the surgery, some people stay in the hospital longer than a day, and incision sites can take several weeks to heal. Recovery from a tumor biopsy via colonoscopy may take a little longer than a colonoscopy performed without a biopsy, but the timing will be similar.
Preparation for the tumor biopsy depends on the location of the tumor and where it is being biopsied. If the cancer being sampled is in the colon, colonoscopy prep is necessary. Liquid biopsy is just like any blood draw but in special tubes. No preparation is needed for this.
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