Cancer is the name given to a collection of
related diseases. In all types of cancer, some of the body’s
cells begin to divide without stopping and spread into
surrounding tissues.
Too many of us are
aware of the prevalence of cancer in our society. Two words
often come up, but are not universally understood. Staging is
for the cancer itself and grade references the actual tumor. There are different grading systems for
different types of cancer. For instance, there is Gleason for
prostate cancer, Bloom-Richardson for breast cancer, Fuhrman
for kidney cancer, etc.
Cancer stage
refers to the size and/or reach of the original (primary) tumor
and whether or not cancer cells have spread (metastasized)
elsewhere in the body. Stages do not change from initial
diagnosis, even if the cancer becomes more aggressive. This is
important for consistent statistical analysis.
Stage 0 (zero) Abnormal
cells are present, but have not spread to nearby tissue. Stages I,
II, and III indicate cancer is present. The higher the number, the
larger the cancer tumor and the more it has spread into nearby
tissues. Stage IV shows the cancer has spread to distant parts of
the body.
Staging is usually based on the TNM system
of classifying cancer. In the TNM system, each cancer is
assigned a letter or number to describe the tumor, node,
and metastases. T stands for the original (primary)
tumor. N stands for nodes and tells whether the cancer has
spread to the nearby lymph nodes. M stands for metastasis.
Tumor grade
is the description of a tumor based on how abnormal the tumor
cells and tumor tissue looks under a microscope. There are four
grades G1 Well differentiated (low grade), G2 Moderately
differentiated (intermediate grade), G3 Poorly differentiated
(high grade), and G4 Undifferentiated (high grade). Grade 3 and
4 tumors tend to grow rapidly and spread faster than tumors with
a lower grade.
Low-grade cancer
cells look more like normal cells and tend to grow and spread
more slowly than high-grade cancer cells. Cancer grade may be
used to help plan treatment and determine prognosis.
In addition, there are
two tumor types, benign, such as moles and warts and malignant,
where the cells invade the surrounding tissue and organs.
Generally, there are
five cancer stages, four tumor
grades, and two tumor types, benign and malignant. Unlike school, a high
stage or grade is not good.