Data for long term survival in thin cutaneous melanoma

FIRST ~ Take a long, slow, cleansing breath.  Now, read slowly...the words below.  DO. NOT. FREAK OUT!!!!!  (I will explain!!!)

Long-Term Survival of Patients with Thin (T1) Cutaneous Melanomas: A Breslow Thickness Cut Point of 0.8 mm Separates Higher-Risk and Lower-Risk Tumors. Lo, Scolyer, Thompson. Ann Surg Oncol. 2018 Jan 12. 

Counterintuitively, more deaths from melanoma occur among patients with thin (T1) primary melanomas (less than and = to 1 mm) than among those with thick primary melanoma because the great majority present with T1 tumors. Therefore, it is important to stratify their risk as accurately as possible to guide their management and follow-up. This study sought to explore the relationship between tumor thickness and prognosis for patients with thin primary melanomas.

A retrospective, single-institution study investigated 6263 patients with cutaneous melanoma (including 2117 T1 cases) who had a minimum follow-up period of 10 years.

For the entire patient cohort, the 10-year melanoma-specific survival (MSS) rate ranged between 92% for the patients with primary melanomas up to 0.3 mm thick and 32% for those with melanomas thicker than 8 mm. When divided into 25-quantile-thickness groups there was a significant difference in 10-year MSS between the two consecutive groups 0.8 and 0.9 mm; the differences in survival were not significantly different for any other consecutive cut points within the less than or equal to 1 mm thickness range, indicating a biologically-relevant difference in outcome above and below 0.8 mm. For the patients treated initially at the authors' institution, the 10- and 20-year MSS rates for those with tumors up to 0.8 mm thick were respectively 93.4 and 85.7%, and for tumors 0.9 to 1.0 mm, the rates were respectively 81.1 and 71.4%. Only 29.3% of the T1 patients who died of melanoma were deceased within 5 years.

A naturally occurring thickness cut point of 0.8 mm predicts higher or lower risk for patients with thin primary cutaneous melanomas. Long-term follow-up assessment of patients with T1 melanoma is important because late mortality due to melanoma is more common than early mortality.

Okay. Take one more slow deep breath.  All this is saying is ~ while death due to a thin melanoma is very rare, it is pretty significant in Stage IV melanoma (given that melanoma sucks great big green hairy wizard balls) and we have to face the reality that many Stage IV folks were once folks with a thin melanoma.  The majority of folks with thin melanomas NEVER progress but, in those that do, the price they pay is pretty dang high!!  So....what the folks in this study did is this: 

They looked at 6263 patients with cutaneous melanoma over 10 years.  For the entire group, survival (leaving out car wrecks, heart attacks, etc.) related to melanoma was 92% if the thin melanoma was 0.3 mm thick or less.  The survival rate was 32% over those 10 years for folks with melanoma thicker than 8 mm.  (Now.  I find this data point a little weird to be included in this abstract.  Is it a typo????  Because they are talking about all melanomas less than 1 mm. Did they mean 0.8 mm???  Or were there patients with thicker melanomas in the entire group reviewed....since they mention there were only 2117 T1 cases of the 6263 they reviewed?  Not sure, but I will assume it is correct and they were just pointing out what happens when you include the odds for ALL the cutaneous melanoma patients' cases they reviewed.) When they really broke the survival rates down for each thickness measure, the only one that had a significant difference in comparison to the others was the break point between those with a 0.8 mm and 0.9 mm lesion. NOW...even there...the 10 and 20 year melanoma survival rates were 93 and 85% for those with 0.8 mm lesions and 81 and 71% for those with lesions measuring 0.9 - 1.0 mm!!!  Only 29% of the T1 patients who did succumb to melanoma passed within 5 years of diagnosis.

And...No!  Before you start yelling, I do not know how the folks who did pass or advance were treated.  There are no dates given for the point from which these patients were followed.  Though, given the 5, 10 and even 20 year follow up that is mentioned, it is likely that with current, FDA approved drugs to treat melanoma at Stage IV and as adjuvant at earlier stages, the death and progression numbers will be greatly reduced in the future.

Now....if you recall this whole conversation about SLNB and thin melanomas: SLN biopsy. Delay of 40 days = WHAT???? (Plus some general guidelines) ....  This article provides some confirmation of why the 0.8 mm cutoff was assumed as the point for consideration of SLNB and advanced a patient's stage to T1b.  However, the data in this paper actually presents an 8% chance of death (while in my argument I was talking about a 5% chance of recurrence) for those with a thin....but thicker than 0.8 mm....cutaneous melanoma lesion.  Overall, I think this paper simply confirms that recurrence (and subsequent death) of/from melanoma is very small in folks with thin lesions less than 0.8 mm and pretty small in folks with thicker "thin" lesions.  However, the risk is not NONE and we should all be smart about that.  Still, with the current advances in melanoma treatments for Stage IV folks and as more folks are attaining effective adjuvant treatment in earlier stages, I am hopeful that the future of MELANOMA is bleak indeed....and is FABULOUS (or at least ever so much better!!!) for RATTIES!!!!!!!!!!!!!!!!!!!

For what it's worth - c