Exceptions to the TNM system
Most cancers fit into the staging system, but there are a few exceptions. Leukemia or other blood-cell cancers can’t be staged because there’s no single solid tumor to measure, and the disease always spreads throughout the body. And staging isn’t very useful for brain cancer because even small tumors can be dangerous if they’re in a vital spot.
There are other staging systems used for these types of cancers, and sometimes childhood cancers and gynecological cancers are staged in different ways as well.
Stage doesn’t generally change
It’s important to understand that staging only applies to the cancer when it’s first diagnosed. The stage doesn’t routinely change over the years, even if the disease gets better or worse. If an M0 cancer eventually spreads to another organ, a doctor will describe it as an M0 cancer that has metastasized. This approach may seem a little confusing, but it helps doctors compare patients and decide on treatments. Think of staging as a first impression.
Tumor cells collected during a biopsy are also checked under a microscope. Cells that look more normal are likely to grow slower; those that look abnormal tend to grow faster. ‘
When cells become cancerous, they start to look less distinct or differentiated, with fuzzy edges. The fastest-growing, most malignant cells will not look anything like normal cells. Based on their appearance, the cells are assigned a number from one to four, which is called the tumor grade.
- GX: Grade can’t be evaluated
- G1: Well-differentiated, cells look close to normal (low grade)
- G2: Moderately differentiated, cells look abnormal (intermediate grade)
- G3: Poorly differentiated, cells look very abnormal (high grade)
- G4: Undifferentiated, cells are not distinct at all (high grade)
There are different grading systems used for different types of cancers. The grade affects the outlook for some cancer more than others, so it may or may not make a big difference in your treatment.
Hopefully, this guide will help you better understand your cancer and how to get the best treatment for the best outcome.