Cancer starts from a single mutated cell and gradually invades other tissue of body. When diagnosed with cancer doctor informs you about the stage of cancer. Staging of cancer refers to the size of tumor and how far it has spread at time of diagnosis. Cancer staging is multifarious and a decisive factor in therapy selection. Cancer staging can be clinical and pathological. Doctors work out a detail on physical exam, tumor biopsy, imagining reports, blood reports, genetic testing (clinical stage) and surgical findings (pathological stage) to assign a stage of cancer. Pathological stage is most accurate picture of cancer which determines patient’s prognosis. Staging of cancer gives a road map about aggressive spread of tumor in body. Staging process is not complete until all tests are done on tumor.
How Stages of cancer helps doctor?
- To make a treatment plan including the type of surgery, chemotherapy or radiotherapy.
- To talk about clear picture of cancer diagnosis with family members.
- To find the severity of cancer and chances of relapse.
- To predict the survival of patient.
- To check how competently treatment will work in group of individuals with similar diagnosis.
- To check eligibility criteria for clinical trials of new drugs; if available.
Doctors commonly make use of TNM System by American Join Committee on Cancer (AJCC) to stage tumor.
T – Size of primary tumor and location
N – Has tumor spread to nearby lymph nodes? If yes, how many?
M – Has tumor spread through other organs / tissues of body? If yes, how much?
In addition to above categories, TNM system also considers check of tumor grade, biomarkers and tumor genetics. Grade of tumor means microscopic comparison of healthy cells in tumor tissue than cancer cells. Presence of more differentiated cells in tissue means a low grade tumor and less differentiated cells means high grade tumor. In short, lower the grade of tumor better the prognosis. Biomarkers or tumor markers are substance present on cell surface, in blood or urine of some cancer patients. Any biomarkers or tumor markers if present make it more or less likely to spread in body. Tumor genetics is presence of certain genetic predisposition in individual’s DNA associated with certain type cancer. Tumor genetics knowledge stimulates new approach in treatment and prevention of cancer.
Cancer stage grouping is done from I to IV, some cancer may also have stage 0.
Stage0 – means only abnormal cells are present which may become cancer, termed as carcinoma in situ. Some doctors and researchers refer stage 0 as pre cancerous changes with a high potential to develop an invasive cancer in near future.
Stage I – means cancer is localized to one small area and not spread to other tissue or lymph nodes. It is called an early stage cancer.
Stage II and III – means larger cancer or tumor and has deeply spread into nearby tissue. They may have spread in lymph nodes but not to other organs of body.
Stage IV – Means cancer has spread to other organ or parts of body. It is often referred as advanced or metastatic cancer.
Other cancer such as Lymphoma, blood cancer and brain cancer have their own staging system.
Cancer staging can sometimes be done after certain treatment like radiotherapy, chemotherapy, hormone therapy, immunotherapy to shrink the size of tumor. This is termed as post-therapy staging. Also, sometimes restaging of cancer is done in case of cancer relapse. New information about cancer is added to original stage where course of cancer prognosis may be different from previous one. Sometimes enough information about cancer is not available; in such cases doctor refer it as unknown stage.