Home Forums Melanoma: Newly Diagnosed – Stages I & II Confusion over Clark’s level and Breslow depth

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  • #20831
    AZJan
    Participant

    Hi,

    One of my friends was recently diagnosed with a 1.3 mm melanoma lesion on the arm, non ulcerated, no mitotic rate identified, clark level IV, no regression, clear margins after WLE.

    After reading various websites/posts, it seems that breslow depth is more predicative of lymph node involvement than clark’s level, which is really doesn’t anymore factor into prognosis. Can anyone explain why this is? Common sense would dictate that Clark’s level would be the BEST indicator of potential metasteses, since it basically describes the level of invasion. This would seemingly correlate directly to “how close the cancerous cells are getting to the blood stream/vessels” and therefore a higher likelyhood of cells being released into the body. On one hand, it seems like my friend is on the “lower end” of concern seeing as the depth is “relatively” thin for being over 1mm…..however on the other end, the Clark’s level would indicate that it has invaded multiple layers of skin, and therefore a high concern.

    I guess I’m a little confused on how 1.3mm can be considered relatively low risk for lymph node involvement for a lesion that requires a SNB, when the clarks level would indicate it’s frighteningly close to the blood stream/vessels. Any feedback would be appreciated!

    #57914
    cohanja
    Participant

    Clark’s Level is the level of skin invaded. Breslow depth is the depth, in millimeters, of the melanoma lesion. Clark’s Level is still called out – especially for thin lesions. But Breslow depth is really the better prognostic factor. Clark’s Level has been found to be too subjective and Breslow is more accurate. At 1.3mm Breslow depth, they meet the standard protocol for a Sentinel Node Biopsy. Clarks level is no longer used for staging melanoma. . . Clarks level went out with the advent of the 2009 American Joint Cancer Committee (AJCC) Staging Guide for melanoma…. they use Breslow Depth

    #57915
    Catherine Poole
    Keymaster

    It is confusing! It was when I was diagnosed and it was scary at a clark level IV. But Dr. Clark was my pathologist and he explained how the Breslow Depth was far better at predicting prognosis. So go with the Breslow and this is just over the depth for a sentinel node biopsy, not terribly high risk, but there could be other factors and one to consider is mitotic rate.

    #57916
    AZJan
    Participant

    Hi,

    Thanks for all the information. Concerning mitotic rate – is “none identifed” the same as 0, and is this a “good” thing? Or, does it mean the pathologist simply didn’t look for it?

    As someone with no knowledge of this at all – to me, “depth” of the lesion in mm would seem not to be as critical, since “1mm” on, say your eyelid, isn’t as deep as on your thigh, etc. Breslow depth seems more relative to the location where the lesion is, whereas Clark’s level actually determines the level of invasion, regardless of skin thickness. So to say that “all that matters is the depth”, without knowing the location and thickness of the skin of that particular area, still confuses me. I would think that “level of invasion” would be a better determinant of true “depth” since it takes the measurement relative to skin thickness.

    That said, these experts are much smarter than me – so if they say breslow depth is what matters most – I believe them! Thanks again!

    #57917
    cohanja
    Participant

    Yes, none identified/0 is a good thing

    #57918
    Worrywart
    Participant

    Breslow has replaced Clarks level because Breslow is more accurate. With that said, its always ‘best’ to have a lower Clarks level.

    #57919
    Catherine Poole
    Keymaster

    I’m not sure of that, since my Dr. Clark and my doctor at the time, crossed that figure out on my pathology (Clarks Level IV) and said they disregarded it in my prognosis. I guess I would like to reassure that if you do have a high Clarks level as I did it doesn’t make you higher risk. It should not be used anymore, period! But pathology is slow to upgrade and change in this country.

    #57920
    cohanja
    Participant

    I thought Clark’s Level of Invasion only affects prognosis in melanomas that are <1 mm depth

    #57921
    Worrywart
    Participant

    I think that with staging, they (the AJCC) use what is most accurate for the population as a whole. They don’t really look at the individual (for example, stage 1 has same survival stats even though some stage 1 are very shallow whereas others have greater depth).

    Breslow helps them to classify melanomas better for the population as a whole.

    Just being realistic and stating my opinion…It would still seem obvious that the smaller Clarks level the better.

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