NCCN Guidelines for Patients® | Melanoma - page 29

NCCN Guidelines for Patients
®
Melanoma, Version 1.2014
27
3
Melanoma staging
TNM scores
TNM scores
The TNM staging system is used to stage melanoma
skin cancer. In this system, each of the letters—T, N,
and M—describes a different area of cancer growth.
Your doctor will assign a score to each letter. TNM
scores are based on the tests described in Part 2.
These scores are used to assign the cancer a stage.
T = Tumor
The T category tells you how thick the primary tumor
is. The T category is given a score from 1 to 4 based
on how deep the tumor has grown into the skin,
measured in mm (
m
illi
m
eters).
See Figure 9.
The
sharp point of a pencil is about 1 mm. For T1 to T4
melanomas, subcategories are given based on two
important factors. The first factor is the ulceration
status—whether or not the tumor’s top skin layer
is present and intact (not ulcerated) or is broken or
missing (ulcerated). The second factor is the dermal
mitotic rate—a measure of how many melanoma
cells are dividing per mm
2
(
m
illi
m
eter squared) of
melanoma tissue.
Tis
means there are abnormal cells in the
epidermis only.
T1
tumors are ≤1 mm thick.
o
T1a
tumors have a mitotic rate of <1/mm
2
and no ulceration.
o
T1b
tumors have a mitotic rate of ≥1/mm
2
or have ulceration or both.
T2
tumors are 1.01 to 2.0 mm thick.
o
T2a
tumors do not have ulceration.
o
T2b
tumors have ulceration.
T3
tumors are 2.01 to 4.0 mm thick.
o
T3a
tumors do not have ulceration.
o
T3b
tumors have ulceration.
T4
tumors are >4.0 mm thick.
o
T4a
tumors do not have ulceration.
o
T4b
tumors have ulceration.
Figure 9. Growth of melanoma
into the skin
The T category is given a score
from 1 to 4 based on how
deep the melanoma tumor has
grown into the skin.
Illustration Copyright © 2014 Nucleus Medical Media, All rights reserved.
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