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Understanding Your Pathology Report

Colon Cancer 101

Information in Your Pathology Report

Every person’s colon cancer is different. It’s important you understand your unique diagnosis and tumor biology as it will help guide your treatment plan and decisions. To provide specific information about your cancer, your physician will perform several tests on your biopsy tumor tissue. The results of this analysis will be contained within your pathology report and will guide your healthcare team in planning the appropriate treatment for you.

Gross description Describes the color, weight and size of tissue as seen by the naked eye.
Grade Indicates how closely the tumor resembles normal colon tissue when viewed under a microstcope. Grading ranges from G1 (looks like normal tissue) to G4 (the tissue looks abnormal). Low-grade (G1 or G2) cancers tend to grow and spread more slowly, and the outlook for survival tends to be better than it does for high-grade cancers (G3 or G4).
Lymphovascular Invasion (LVI) Indicates whether cancer cells are present in blood vessels or the lymphatic system. When LVI is present, it is assumed that the cancer has acquired the genetic mutation necessary to create its own blood vessels and may have begun to spread cancer cells to other parts of the body.
T-stage Describes how deeply the tumor has invaded into the wall of the colon.
Lymph nodes Indicates whether (and how many) lymph nodes tested positive for cancer cells.
Tumor cell type The type of cancer cells in the tumor (evaluated by a pathologist), with adenocarcinoma being the most common type.
Margins The area at the edge of the specimen being examined by the pathologist. Positive margins mean that cancer cells are found at the edge of the material removed; negative/not involved/clear margins mean that no cancer cells are found at the outer edge. Close margins are neither positive nor negative.
MMR (mismatch repair) Biological pathway responsible for correcting errors that commonly occur during DNA replication. Functional MMR can be determined through a microsatellite instability (MSI) test.
KRAS mutation Mutated gene found in the tumors of 35-40% of metastatic colon cancer patients; research has shown patients with KRAS mutations do not benefit from EGFR therapies.

Pathologic Staging and TNM Status

Colon cancer staging ranges from Stage 0 (pre-cancerous) to Stage IV (cancer has spread to distant organs.). Colon cancer is staged by considering three pieces of information:

  • Tumor (T): Provides information about the size of the tumor and how far it has grown into the walls of the colon or nearby organs.
  • Lymph Node (N): Describes whether the cancer has spread to nearby lymph nodes, and if so, how many lymph nodes are affected.
  • Metastasis (M): Tells whether the cancer has spread (metastasized) to distant sites of the body, such as the lungs or liver.

A number is added to each letter to indicate the size and/or extent of the tumor and the degree of cancer spread.i

  • TX: Tumor cannot be measured.
  • T0: No evidence of a primary tumor (it cannot be found).
  • Tis: Tis: Cancer cells are only growing in the most superficial layer of tissue, without growing into deeper tissues. This may also be called in situ cancer or pre-cancer.
  • T1, T2, T3, T4: Describes the tumor size and/or amount of spread into nearby structures; the higher the T number, the larger the tumor and/or the more it has grown into nearby tissues.
  • NX: Nearby lymph nodes cannot be evaluated.
  • N0: Nearby lymph nodes do not contain cancer.
  • N1, N2, N3, etc: Describes the number of nearby lymph nodes affected by cancer; the higher the N number, the greater the spread to nearby lymph nodes.
  • MX: Distant metastasis cannot be evaluated.
  • M0: No distant cancer spread was found.
  • M1: Cancer has spread to distant organs or tissues (distant metastases were found).

TNM Staging ii, iii

The stage of a cancer is determined by combining the T, N, and M classifications.

Colon Cancer StagesThe following is a basic breakdown of how colon cancer is staged:

  • Stage 0 (also called carcinoma in situ): Earliest cancer stage; the cancer is located on the outermost layer (mucosa) of the colon wall.
  • Stage I: The cancer has spread to the second (submucosa) and third (muscularis propria) layer of the colon wall, but not to the outer colon wall or beyond.
  • Stage II: The cancer has spread to or through the colon wall without involving lymph nodes.
  • Stage III: The cancer has spread through the colon wall and into lymph nodes, but has not spread to other areas of the body.
  • Stage IV: The cancer has grown from the colon and spread to other areas of the body (i.e. liver and lungs).

Anatomy of the Colon

Colon cancer anatomy

Your cancer stage determines the appropriate treatment, so talk with your doctor to understand your individual diagnosis and treatment options. Learning all you can about your specific type of colon cancer will allow you and your doctor to develop a personalized treatment plan.

Visit Fight Colorectal Cancer to learn more about colon cancer staging.

Additional information about colon cancer staging is found in the chart below: iv, v, vi

Stage TNM Status Description
Stage 0 Tis
N0
M0
Cancer is found in the innermost lining (mucosa) of the colon or rectum only. Stage 0 cancer is also called carcinoma in situ, or non-invasive colon cancer.
Stage 1 T1
N0
M0
Invasive colon cancer (cells breaking through to or invading normal surrounding colon tissue) in which:
  • The cancer has spread beyond the mucosa to the middle layers
    • T1 indicates the tumor has invaded the submucosa
    • T2 indicates invasion of the muscularis propria.
  • The cancer has not spread to the lymph nodes
  • The cancer has not spread to distant sites of the body
T2
N0
M0
Stage 2A T3
N0
M0
Invasive colon cancer in which:
  • The cancer has spread beyond the subserosa or has spread to nearby tissue around the colon
  • The cancer has not spread to the lymph nodes
  • The cancer has not spread to distant sites of the body
Stage 2B T4a
N0
M0
Invasive colon cancer in which:
  • The cancer has spread through all layers of the colon
  • The cancer has not spread to the lymph nodes
  • The cancer has not spread to distant sites of the body
Stage 2C T4b
N0
M0
Invasive colon cancer in which:
  • The cancer has spread through the colon to other organs
  • The cancer has not spread to the lymph nodes
  • The cancer has not spread to distant sites of the body
Stage 3A T1 to T2
N1/N1c
M0
Invasive colon cancer in which:
  • The cancer has spread to the submucosa or muscularis propria
  • The cancer has spread to as many as 3 lymph nodes.
  • The cancer has not spread to distant sites of the body.
T1
N2a
M0
Invasive colon cancer in which:
  • The cancer has spread to the submucosa.
  • The cancer has spread to 4-6 lymph nodes.
  • The cancer has not spread to distant sites of the body
Stage 3B T3 to T4a
N1
M0
Invasive colon cancer in which:
  • The cancer has spread at least to the subserosa up to the outer surface of the colon
  • The cancer has spread to as many as 3 lymph nodes
  • The cancer has not spread to distant sites of the body
T2 to T3
N2a
M0
Invasive colon cancer in which:
  • The cancer has spread at least to the muscularis propria up to the subserosa
  • The cancer has spread to 4-6 lymph nodes
  • The cancer has not spread to distant sites of the body
T1 to T2
N2b
M0
Invasive colon cancer in which:
  • The cancer has spread to the submucosa or muscularis propria
  • The cancer has spread to ≥7 lymph nodes
  • The cancer has not spread to distant sites of the body
Stage 3C T4a
N2a
M0
Invasive colon cancer in which:
  • The cancer has spread through the outer surface of the colon
  • The cancer has spread to 4-6 lymph nodes
  • The cancer has not spread to distant sites of the body
T3 to T4a
N2b
M0
Invasive colon cancer in which:
  • The cancer has spread at least to the subserosa up to the outer surface of the colon
  • The cancer has spread to ≥7 lymph nodes
  • The cancer has not spread to distant sites of the body
T4b
N1 to N2
M0
Invasive colon cancer in which:
  • The cancer has spread through the wall of the outer colon and is attached to or has grown into other nearby tissues or organs
  • The cancer has spread to 1-4 lymph nodes
  • The cancer has not spread to distant sites of the body
Stage 4A Any T
Any N
M1a
Also known as advanced or metastatic. The cancer has spread to one (M1a) or multiple (M1b) other sites of the body, such as the liver, lungs, abdominal lining, or ovaries.
Any T
Any N
M1b

 

REFERENCES
i. American Cancer Society – Cancer Staging
ii. National Cancer Institute – What is the TNM system?
iii. American Joint Committee on Cancer – Colon and Rectum Cancer Staging
iv. American Cancer Society – Colorectal cancer stages
v. Cancer Treatment Centers of America – Colorectal cancer stages
vi. ASCO Cancer.net – Colorectal Cancer: Stages

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