1119P - Stage IIIA melanoma with isolated tumor cells in lymph nodes: Time for reviewing the AJCC v8 classification

Background

The classification of stage III melanoma has significantly changed in the American Joint Committee on Cancer 8^th version (AJCC v8). Besides including four new substages, AJCC v8 defines that lymph nodes (LN) with metastatic tumor cells, regardless of the size and the technic used to identify it, should be considered tumor-involved LN. This implies that even thin melanomas with isolated tumor cells (ic) in LN will be classified as stage IIIA, potentially upstaging patients (pts) with good prognosis.

Methods

Patients with cutaneous melanoma diagnosed with stage I-III between 2000-2020 at the Centre of Dermatooncology, University-Hospital of Tuebingen, were included. A cohort of stage IIIA (ic) pts from the DeCOG trial was used as a validation cohort. Relapse-free survival (RFS) and distant metastasis-free survival (DMFS) were evaluated using Kaplan-Meier estimates. Data on pts and tumor characteristics will also be presented.

Results

The Tuebingen cohort included 106 pts with stage IIIA (ic) and 132 pts with stage IIIA with a LN metastasis >0.1 mm (from now on stage IIIA). The validation cohort from the DeCOG trial consisted of 39 pts with melanoma IIIA (ic) and 104 pts with stage IIIA. The median follow-up (mFU) for stage IIIA (ic) and IIIA in the CMMR cohort was 64 and 60 months (95% CI 34-97 and 35-106), respectively. The mFU for stage IIIA (ic) and IIIA in the DeCOG cohort was 64 and 62 months (95%CI 47-95 and 37-86), respectively. In the Tuebingen cohort, 10y RFS rates for stage IIIA (ic) and IIIA were 82% (95% CI 72-92) and 48% (95% CI 38-58), respectively (p<0.001). The 10y DMFS rates for stage IIIA (ic) and IIIA were 87% (95% CI 79-96) and 55% (95% CI 44-66), respectively; (p<0.001). In the DeCOG cohort, 10y RFS for stage IIIA (ic) and stage IIIA were 88% (95% CI 77-99) and 35% (95% CI 7-62), respectively; (p=0.009). The 10y DMFS for stage IIIA (ic) and IIIA was 88% (95% CI 77-99) and 60% (95% CI 39-80), respectively (p=0.061).

Conclusions

AJCCv8 Stage IIIA (ic) melanoma has a prognosis similar to stage IB, statistically significantly better than Stage IIIA. LN with isolated tumor cells should not be considered tumor-involved LN, and this should be reviewed in the new AJCC edition.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

T.M.S. Amaral: Financial Interests, Personal, Writing Engagement: CeCaVa; Financial Interests, Personal, Invited Speaker: BMS, Novartis, Pierre Fabre; Financial Interests, Institutional, Funding: Novartis, Neracare, Sanofi, Skyline-Dx; Financial Interests, Institutional, Research Grant: Novartis, iFIT; Financial Interests, Institutional, Local PI: IO Biotech, MSD, University Hospital, Essen, Roche; Financial Interests, Institutional, Coordinating PI: Unicancer; Non-Financial Interests, Member: Portuguese Society for Medical Oncology, ASCO; Other, Clinical expert: INFARMED. R. Stadler: Financial Interests, Personal, Advisory Board: Kyowa Kirin, Stemline, 4SC. A. Forschner: Financial Interests, Personal and Institutional, Invited Speaker: Pierre Fabre, Novartis, MSD, BMS; Financial Interests, Institutional, Advisory Board: Immunocore, Pierre Fabre, MSD, BMS, Novartis; Financial Interests, Institutional, Research Grant: BMS Stiftung Immunonkologie; Financial Interests, Personal, Other, Travel, Accommodation, Expenses: Pierre Fabre, Novartis. L. Flatz: Financial Interests, Personal, Stocks or ownership: Hookipa Pharma; Financial Interests, Personal, Invited Speaker: BMS, Novartis, Sanofi; Financial Interests, Personal, Advisory Board: BMS, Novartis, Sanofi, Philogen; Financial Interests, Institutional, Research Funding: Hookipa Pharma; Financial Interests, Personal, Royalties: Hookipa Pharma. C. Garbe: Financial Interests, Personal, Advisory Board: CeCaVa, Novartis, NeraCare, BMS, Philogen, Roche, Sanofi, MSD. U. Leiter-Stoppke: Financial Interests, Institutional, Research Grant: MSD; Financial Interests, Personal, Invited Speaker: MSD, Novartis, Sun Pharma, Allmiral Hermal, Sanofi; Financial Interests, Personal, Other, Travel support: Sun Pharma; Financial Interests, Personal, Advisory Board: MSD, Novartis, Sun Pharma, Allmiral Hermal, Sanofi; Non-Financial Interests, Personal, Other, Board member: ADO (DECOG). All other authors have declared no conflicts of interest.