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Stage 1

Find out what stage 1 melanoma skin cancer means and about treatment options.

Stage 1 is part of the number staging system and means your melanoma is at an early stage. It is only in the skin and there is no sign that it has spread to lymph nodes or other parts of the body.

Stage 1 can be divided into 1A and 1B.

Stage 1A

Stage 1A means all of the following:

  • the melanoma is less than 1mm thick
  • the covering layer of skin over the tumour is not broken (it is not ulcerated)
  • it has a mitotic rate of less than 1/mm (squared)

Mitotic rate describes the number of cells that are in the process of dividing in a certain amount of melanoma tissue. 

Stage 1B

Stage 1B means one of the following:

  • the melanoma is less than 1mm thick and the skin is broken (ulcerated)
  • it has a mitotic rate of at least 1/mm (squared)
  • it is between 1 and 2mm and is not ulcerated

TNM stages

The TNM staging system stands for Tumour, Node, Metastasis.

  • T describes the size of the tumour
  • N describes whether there are any cancer cells in the lymph nodes
  • M describes whether the cancer has spread to a different part of the body

In the TNM staging system stage 1A is the same as T1a, N0, M0

Stage 1B is the same as one of the following:

  • T1b, N0, M0
  • T2a, N0, M0


The stage of your cancer helps your doctor to decide what treatment you need. Treatment also depends on:

  • where the cancer is
  • other health conditions

Surgery is the main treatment. Doctors remove the abnormal mole and a small area of surrounding skin. You usually have a second operation to remove a larger area of healthy tissue around where the melanoma was. This is called a wide local excision. 

For stage 1A melanoma, if your doctors are sure that they removed enough tissue, this is all the treatment you need.

For stage 1B  melanoma, your doctor might offer you a test to check your lymph nodes. You can choose whether to have this test. The test is called a sentinel lymph node biopsy and you usually have it under a general anaesthetic.

Last reviewed: 
12 Nov 2015
  • Melanoma assessment and management
    National Institute for Health and Care Excellence, July 2015

  • Cancer: Principles and practice of oncology (10th edition)
    VT De Vita, TS Lawrence and SA Rosenberg
    Lippincott, Williams and Wilkins, 2015   

  • TNM Classification of Malignant Tumours (7th edition)
    International Union Against Cancer   
    L.H. Sobin, M.K. Gospodarowicz, Ch. Wittekind
    John Wiley & Sons, Hoboken, New Jersey, 2009

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