What Do The Different Stages of Cancer Mean?

An initial diagnosis of cancer is likely very overwhelming for the patient, but knowing the stage of the cancer can tell one critical part of the story: is it a tiny spark on the countertop or has the house started to burn down? Effective categorization of the stage of cancer is important for oncologists in assessing the seriousness of the disease, and in determining the appropriate treatments.

Types of Staging Systems

There are preliminarily 2 types of staging systems that are used to broadly categorize most common types of cancer: the number system and the TNM system.

Having a limited number of staging systems allows doctors to have a common language to describe the size and spread of the cancer, and to develop standard treatment guidelines to treat a variety of cancers.

The Number System

• Stage 0

  • Abnormal pre-cancerous cells that haven't spread from where they had started

    • Known as "carcinoma in situ"

• Stage I

  • Small tumor that hasn't spread

• Stage II

  • Cancer that has grown in size and a chance that it has spread to nearby lymph nodes

• Stage III

  • Cancer has grown deeper into surrounding tissues and has spread to nearby lymph nodes

• Stage IV

  • Cancer has spread, metastasized, from where it started to another organ in the body.

    • Known as "Metastatic Cancer"

The TNM System

• The TNM system is the abbreviated form of tumor, node, metastasis.

  
  

  • T: Describes the size and extent of the tumor.

    • The scale ranges from 1-4, with 1 being the smallest detectable and 4 being the largest.

  • N: Describes the extent to which the tumor has spread to the surrounding lymph nodes.

    • The scale ranges from 0-3, with 0 being no lymphs nodes containing cancer cells and 3 meaning a lot of lymph nodes contain cancerous cells.

  • M: Refers to whether the cancer has spread to the other parts of the body.

    • The scale ranges from 0-1, with 0 meaning that the cancer hasn't metastized and 1 meaning it has.

Treatments Options For Each Stage

Stage 0 Cancer

• Surgery: Often the only treatment needed, because the abnormal cells haven’t spread.

  • Why effective: Since it’s caught very early on, removing the cells completely can mean the patient is essentially “cured.”

Stage I Cancer

• Surgery: Main treatment, since the cancer is small and localized.

• Radiation therapy: In some cases it is used after surgery to kill any tiny traces of cancer cells left behind.

  • Why effective: At this stage, the treatment aims to destroy cancer at its source before it spreads further.

Source: Skin Cancer and Reconstructive Surgery Center

Stage II & III Cancer

• Surgery: Tumors are larger or have started spreading to nearby lymph nodes, so it can't completely remove the cancerous cells on its own, but still plays a key role.

• Radiation therapy: Helps to shrink tumors before surgery, or kill remainder of cancerous cells afterwards.

• Chemotherapy: Given either before or after surgery to attack some of the "hidden" cancer cells throughout the body.

  • Why effective: The cancer has now progressed quite far, so a multitude of treatments are usually required to combat it.

    
    

    

    Source: University of Minnesota School of Public Health

Stage IV Cancer

• Chemotherapy: Cancer has reached a point where the chemotherapy serves to slow cancer spread to extend survival.

• Immunotherapy: Enhances the patient's immune system's ability to recognize and fight cancer cells.

• Targeted therapy: Special drugs that target specific genetic mutations that are critical to the progression of the cancer.

• Radiation or surgery: Used mainly to relieve symptoms, not as a cure.

  • Why effective: Almost always in this case irreparable damage has been done, so treatment often focuses on long-term control and improving quality of life, rather than complete removal.

Sources

Liu, Beilei, et al. “Exploring treatment options in cancer: Tumor treatment strategies.” Signal Transduction and Targeted Therapy, vol. 9, no. 1, 17 July 2024, https://doi.org/10.1038/s41392-024-01856-7.

Cleveland Clinic Medical. “Cancer Staging: How Does It Work?” Cleveland Clinic, 6 May 2025, my.clevelandclinic.org/health/diagnostics/22607-cancer-stages-grades-system.

“Stages of Cancer.” Cancer Research UK, 5 Dec. 2024, www.cancerresearchuk.org/about-cancer/what-is-cancer/stages-of-cancer.

“Understanding the Stages of Cancer: What Each Stage Means for Treatment.” House Medicine, housemedicine.com/understanding-the-stages-of-cancer-what-each-stage-means-for-treatment/.

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