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Skin Cancer

Determining the Stage of the Cancer


The final step before discussing treatment options is a determination of the stage of the cancer. As with all cancers of the head and neck, doctors in the U.S. use the AJCC Cancer Staging Manual (7th Ed) to determine the stage based on three factors.

Factors that go into determining the stage of the cancer
T Characteristics of the main tumor mass
N Status of the lymph nodes in the neck (i.e., evidence of cancer spread)
M Status of cancer spread to parts of the body outside of the head and neck

Your clinical stage

Clinical staging (cTNM) is determined from any information your doctor might have about how extensive the cancer is BEFORE starting any treatment. Stage is determined based on your doctor’s physical exam, imaging studies, laboratory work and biopsies. Classification of clinical stage is described using the lowercase prefix c (e.g., cT, cN, cM).

Once the diagnostic tests are completed, before deciding what type of treatment you are going to receive, you should be given a clinical stage that will look similar to the example below.

CLINICAL STAGE
Example
Site Skin
Location Left Cheek
Type Basal Cell Carcinoma
cT cT3
cN cN0
cM cM0
cStage cIII

* The lowercase subscript c indicates that this is a CLINICAL STAGE, the stage assigned based on all information available to your doctor before starting treatment.

Your pathologic stage

Pathologic staging (i.e., pTNM) provides more data. Classification of pathology stage is described using the lowercase prefix p (e.g., pT, pN, pM). This may or may not differ from the clinical stage.

After surgery, you should get a pathologic stage in regards to your tumor. It will look almost like the clinical stage you received before starting treatment, but notice the “p” that indicates the stage group is based on an analysis of the entire tumor, with or without lymph nodes, under a microscope by a pathologist. In many cases, the pathologic stage will be the same as the clinical stage, but sometimes it will change.

After surgery, and after the pathologist has evaluated all of the tumor that was removed, you should be given a pathologic stage that looks something like this:

PATHOLOGIC STAGE
Example
Site Skin
Location Right Forehead
Type Squamous Cell Carcinoma
pT pT3
pN pN2b
cM cM0
pStage pIV

* The lowercase subscript p indicates that this is a PATHOLOGIC STAGE, the stage assigned after tumor removal and confirmation of cancer by a pathologist.

There are also a number of other lowercase prefixes that might be used in the staging of your cancer.

  • The subscript y (yTNM) is used to assign a cancer stage after some sort of medical, systemic or radiation treatment is given (Posttherapy or Postneoadjuvant Stage). It is typically combined with either a clinical or pathologic stage. For example, ycT2N0M0 indicates that after some sort of non-surgical therapy, the new clinical stage is T2N0M0.
  • The subscript r (rTNM) is used when the tumor has recurred after some period of time in which it was gone. This is called Retreatment Classification Stage. Your doctor will use all the available information to assign you a retreatment stage.

The staging of skin cancers does vary a little based on the type of skin cancer. According to the AJCC 7th edition staging manual, skin cancer staging is broken down into the following categories:

  • Staging of cutaneous squamous cell carcinoma and other cutaneous carcinomas
  • Staging of Merkel cell carcinoma
  • Staging of malignant melanoma of the skin
  • Staging of cutaneous lymphoma (talk to your medical oncologist about this one)

Staging of Skin Squamous Cell Carcinoma, Basal Cell Carcinoma and Other Skin Carcinomas

This is the staging criteria used for squamous cell cancers of the skin and basal cell cancers of the skin. It can also be used for other skin cancer types that do not have their own staging system. This staging system does not apply to melanoma skin cancers, cancers on the eyelid or lymphomes of the skin.

T stage: the main tumor mass

Based on a physical examination and review of any imaging, your doctor should be able to give you a T stage that falls within one of the following categories.

Tx The primary tumor cannot be evaluated.
T0 There is no evidence of a primary tumor.
Tis The cancer is in situ, meaning it has not invaded into deeper layers.
T1 The tumor is 2 centimeters or less at its largest point. Also, it must have fewer than two high-risk features.
T2 The tumor is more than 2 centimeters at its largest point, OR the tumor can be of any size with two or more high-risk features.
T3 The tumor invades the cheekbone (maxilla), jawbone (mandible), eye socket (orbit) or the bone of the ear (temporal bone).
T4 The tumor invades nerves at the base of the skull.

High-risk features are:

  • The cancer is more than 2 millimeters thick.
  • The cancer extends down to Clark level IV or more.
  • There is invasion into/around nerves.
  • The main tumor is located at the ear.
  • The main tumor is on the part of the lip that has hair.
  • The tumor is either poorly differentiated or undifferentiated.

N stage: spread of cancer to the lymph nodes in the neck

Next, your doctor will use all the available information and assign you an N stage. This is based on the assessment of whether the cancer has spread to lymph nodes in the neck.

Nx The neck lymph nodes cannot be assessed.
N0 There is no evidence of any spread to the nodes.
N1 It looks like there is a single node, on the same side of the main tumor, that is 3 centimeters or less in greatest size.
N2a The cancer has spread to a single node on the same side as the main tumor, and it is more than 3 centimeters but less than or equal to 6 centimeters in greatest dimension.
N2b More than one lymph node has cancer, on the same side as the main tumor, but none are more than 6 centimeters.
N2c There are lymph nodes in the neck on either the opposite side as the main cancer or on both sides of the neck, but none are more than 6 centimeters.
N3 There is spread to one or more neck lymph nodes, and the size is more than 6 centimeters.

M stage: spread of cancer outside the head and neck

Finally, based on an assessment on the entire body, you will be assigned an M stage.

M0 No evidence of distant spread.
M1 There is evidence of spread outside of the head and neck (i.e., in the lungs, bone, brain, etc.).

Your cancer stage

After TNM staging, your doctor can assign a cancer stage based on the following chart.

Stage 0 Tis N0 M0
Stage 1 T1 N0 M0
Stage 2 T2 N0 M0
Stage 3 T3 N0 M0
T1 N1 M0
T2 N1 M0
T3 N1 M0
Stage 4 T1 N2 M0
T2 N2 M0
T3 N2 M0
Any T N3 M0
T4 Any N M0
Any T Any N M1

Staging of Malignant Melanoma of the Skin

For melanoma, the T stage is all about the tumor thickness.

T stage for malignant melanoma of the skin

Tx The primary tumor cannot be evaluated (it was curetted out or has severely regressed).
T0 There is no evidence of a primary tumor.
Tis The cancer is in situ, meaning it has not invaded into deeper layers.
T1a The tumor thickness is 1 millimeter or less (without ulceration and mitosis <1/mm2).
T1b The tumor thickness is 1 millimeter or less (with ulceration or mitosis >1/mm2).
T2a The tumor thickness is 1.01 mm to 2 mm (without ulceration).
T2b The tumor thickness is 1.01 mm to 2 mm (with ulceration).
T3a The tumor thickness is 2.01 mm to 4.0 mm (without ulceration).
T3b The tumor thickness is 2.01 mm to 4.0 mm (with ulceration).
T4a The tumor thickness is more than 4.0 mm (without ulceration).
T4b The tumor thickness is more than 4.0 mm (with ulceration).

Ulceration means there is a wound caused by a break in the surface of the tumor where dead cells are present. This is seen under the microscope by a pathologist.

N stage for malignant melanoma of the skin

Next, your doctor will use all the available information and assign you an N stage. This is based on the assessment of whether the cancer has spread to lymph nodes in the neck.

Nx The neck lymph nodes cannot be assessed (for example, they were removed for another reason in the past).
N0 There is no evidence of any spread to the lymph nodes.
N1 1 node
N1a if micrometastasis
N1b if macrometastasis
N2 2-3 nodes
N2a if micrometasasis
N2b if macrometasasis
N2c if in-transit metastasis or satellite metastasis without any positive nodes
N3 4 or more nodes with cancer, or nodes that are stuck together, or in transit or satellite metastases with positive nodes
  • Micrometastasis: This is used when there appear to be no large cancerous lymph nodes, but after lymph nodes were removed, it turns out there was microscopic involvement.
  • Macrometastasis: This is used when there are detectable lymph nodes before being removed that are then confirmed to be positive when examined under a microscope.
  • In transit metastasis: These are tumor deposits in the skin or just under the skin more than two centimeters away from the primary lesion. The tumor cells travel within lymphatic channels.
  • Satellite metastasis: These are tumor deposits in the skin or just under the skin that are within two centimeters of the primary lesion. The tumor cells travel within lymphatic channels.

M stage for malignant melanoma of the skin

Finally, based on an assessment on the entire body, you will be assigned an M stage. Notice that the M stage for melanoma takes into account a special blood test for lactate dehydrogenase (LDH). If the level of this protein in the blood is elevated, the M stage is automatically M1c.

M0 No evidence of distant spread
M1a Spread to the skin, subcutaneous tissue, or lymph nodes distant from the primary tumor and the regional basin of lymph nodes
M1b Spread to the lung
M1c Spread to any other body site

Your Cancer Stage for Malignant Melanoma of the Skin

After TNM staging, your doctor can assign a cancer stage based on the following chart.

Stage 0 Tis N0 M0
Stage 1A T1a N0 M0
Stage 1B T1b N0 M0
T2a N0 M0
Stage 2a T2b N0 M0
T3a N0 M0
Stage 2b T3b N0 M0
T4a N0 M0
Stage 2c T4b N0 M0
Stage 3 Any T N1-3 M0
Stage 4 Any T Any N M1

Staging of Merkel Cell Carcinoma

T stage for Merkel cell carcinoma

Based on your doctor’s physical examination and review of any imaging, he or she should be able to give you a T stage that falls within one of the following categories.

Tx The primary tumor cannot be evaluated.
T0 There is no evidence of a primary tumor.
Tis The cancer is in situ, meaning it has not invaded into deeper layers.
T1 The tumor is 2 centimeters or less at its largest point.
T2 The tumor is more than 2 centimeters but not more than 5 centimeters at its largest point.
T3 The tumor is more than 5 centimeters at its largest point.
T4 The tumor invades bones, muscles, fascia or cartilage.

N stage for Merkel cell carcinoma

Next, your doctor will use all the available information and assign you an N stage. This is based on the assessment of whether the cancer has spread to lymph nodes in the neck.

Nx The neck lymph nodes cannot be assessed.
N0 There is no evidence of any spread to the lymph nodes.
cN0 Based on your doctor’s examination and review of the imaging, there do not seem to be any lymph nodes.
pN0 After looking at lymph nodes under a microscope following removal, there is no evidence of spread to neck lymph nodes.
N1a Micrometastasis:
This is used when one or more lymph nodes are removed “electively,” and it turns out there is cancer within the lymph nodes.
N1b Macrometastasis:
This is used when there are enlarged lymph nodes identified before removing them that are then confirmed to be positive under a microscopic test after removal.
N2 In transit spread:
This is used when there is a tumor separate from the main lesion and located either between the main lesion and the draining lymph nodes or anywhere further away (distal) to the primary tumor.

M stage for Merkel cell carcinoma

Finally, based on an assessment on the entire body, you will be assigned an M stage.

M0 No distant spread
M1a Spread to the skin, subcutaneous tissue or lymph nodes separate from those related to the main tumor
M1b Spread to the lung
M1c Spread to any other body site or spread to any distant site with an elevated LDH level in the blood

Your cancer stage for Merkel Cell Carcinoma

After TNM staging, your doctor can assign a cancer stage based on the following chart.

Stage 0 Tis N0 M0
Stage 1A T1 pN0 M0
Stage 1B T1 cN0 M0
Stage 2A T2-3 pN0 M0
Stage 2B T2-3 cN0 M0
Stage 2C T4 N0 M0
Stage 3A Any T N1a M0
Stage 3B Any T cN1/N1b/N2 M0
Stage 4 Any T Any N M1

 

References

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2 American Cancer Society. Cancer Facts & Figures 2012. Atlanta: American Cancer Society; 2012.

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5 Referenced with permission from The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Basal Cell and Squamous Cell Skin Cancers V.1.2014. © National Comprehensive Cancer Network, Inc 2014. All rights reserved. Accessed Jan. 22, 2014. To view the most recent and complete version of the guideline, go online to www.nccn.org. NATIONAL COMPREHENSIVE CANCER NETWORK®, NCCN®, NCCN GUIDELINES®, and all other NCCN Content are trademarks owned by the National Comprehensive Cancer Network, Inc.

6 Referenced with permission from The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Melanoma V.3.2014. © National Comprehensive Cancer Network, Inc 2014. All rights reserved. Accessed Feb 12, 2014. To view the most recent and complete version of the guideline, go online to www.nccn.org. NATIONAL COMPREHENSIVE CANCER NETWORK®, NCCN®, NCCN GUIDELINES®, and all other NCCN Content are trademarks owned by the National Comprehensive Cancer Network, Inc.

7 Referenced with permission from The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Merkel Cell Carcinoma V.1.2014. © National Comprehensive Cancer Network, Inc 2014. All rights reserved. Accessed Jan. 22, 2014. To view the most recent and complete version of the guideline, go online to www.nccn.org. NATIONAL COMPREHENSIVE CANCER NETWORK®, NCCN®, NCCN GUIDELINES®, and all other NCCN Content are trademarks owned by the National Comprehensive Cancer Network, Inc.

8 Referenced with permission from the NCCN Guidelines for Patients®: Melanoma V.1.2013. © National Comprehensive Cancer Network, Inc 2013. All rights reserved. Accessed July 2, 2013. To view the most recent and complete version of the guideline, go online to www.nccn.org. NATIONAL COMPREHENSIVE CANCER NETWORK®, NCCN®, NCCN GUIDELINES®, and all other NCCN Content are trademarks owned by the National Comprehensive Cancer Network, Inc.

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