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Staging Colorectal Cancer: How Doctors Determine the Extent of the Disease
Published: Sep 30, 2024
When colorectal cancer is diagnosed, determining its stage is crucial for planning treatment and estimating prognosis. Staging involves a series of tests and procedures to assess how far the cancer has spread.
The TNM Staging System
Doctors use the TNM system to stage colorectal cancer. T describes the size of the tumor and how deeply it has grown into the bowel wall. N indicates whether cancer has spread to nearby lymph nodes. M shows if the cancer has metastasized to other parts of the body. These factors are combined to determine the overall stage, ranging from 0 (very early) to IV (advanced).
Imaging Tests for Staging
Several imaging tests help determine the cancer's stage. CT scans of the chest, abdomen, and pelvis can show if the cancer has spread to nearby organs or distant sites. For rectal cancer, MRI provides detailed images of the rectum and surrounding tissues. PET scans may be used to look for cancer spread throughout the body, especially if other tests are unclear.
Surgical Staging
The most accurate staging often occurs during surgery to remove the cancer. The surgeon can directly observe the extent of the tumor and nearby spread. Lymph nodes are removed and examined under a microscope to check for cancer cells. In some cases, laparoscopy (a minimally invasive procedure) might be done before major surgery to check for small areas of cancer spread.
Blood Tests and Biomarkers
Blood tests can provide additional information for staging. Liver function tests may indicate if cancer has spread to the liver. The tumor marker CEA (carcinoembryonic antigen) can be elevated in some colorectal cancers and may help monitor treatment response. However, CEA isn't specific to colorectal cancer and isn't used alone for diagnosis or staging.
Frequently Asked Questions
It can take several days to weeks to complete all necessary tests.
Yes, cancer can progress to a higher stage if it grows or spreads.
Usually yes, to confirm cancer and examine its characteristics.
It's generally quite accurate but not perfect.
Stage is crucial but other factors also influence treatment decisions.
A Critical Step
Accurate staging of colorectal cancer is a complex but essential process that guides treatment decisions and helps predict outcomes for patients.
References
- American Cancer Society. Colorectal Cancer Stages. cancer.org
- National Cancer Institute. Colorectal Cancer Treatment (PDQ®)–Health Professional Version. cancer.gov
- American Joint Committee on Cancer. AJCC Cancer Staging Manual, 8th Edition. cancerstaging.org
This article has been reviewed for accuracy by one of the licensed medical doctors working for Doctronic. Always discuss health information with your healthcare provider.
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