Supplemental Figure 2. Derivation of proposed T-category for Primary Vulvar Melanoma. from Tumor Thickness and Mitotic Rate Robustly Predict Melanoma-Specific Survival in Patients with Primary Vulvar Melanoma: A Retrospective Review of 100 Cases

(A, B, C) We first assigned patients with PVM to a T-category according to the AJCC for PCM (7th Edition). (A) Shows the AJCC schema and the number of patients assigned to each category. (B) Kaplan Meier DSS curves for patients stratified by AJCC T-categories demonstrate robust prognostic differences for patients with PVM and pT1 and to an extent pT2 disease from those with pT3 and pT4 disease, but less robust stratification among those patients with PVMs {less than or equal to}2.00 mm; pT1 versus pT2 (isolated in C) or >2.0 mm; pT3 and pT4. (D, E, F) Because both tumor thickness and mitotic rate were independent prognostic factors for DSS and because mitotic rate showed a natural prognostic separation at 2 mitotic figures/mm2 (as shown in Figure 1D), we first asked whether a T-category according to the conventional AJCC cut-offs ({less than or equal to}1.0, 1.01-2.0, 2.01-4.0 and >4.0 mm) subsequently modified by mitotic rate (a: <2/mm2 and b: {greater than or equal to}2/mm2) instead of ulceration (as in the AJCC) would effectively stratify patient outcomes. (D) Shows this initial 'alternative T-category' schema and the number of patients assigned to each category. (E) Kaplan Meier DSS curves for patients assigned to the alternative T-categories demonstrate longer DSS for patients with pT1a and pT2a PVM compared to all other patients in the schema. In particular, patients with PVM >2.0 mm (pT3 and pT4) had a short DSS independent of mitotic rate. More importantly, among patients with a tumor thickness {less than or equal to}2.0 mm (pT1 or pT2), only those with mitotic rate {greater than or equal to}2/mm2 had a short DSS, which was essentially superimposable with patients with pT3 and pT4 PVM in this schema. (F) Kaplan-Meier survival curve for patients with pT1 and pT2 PVMs show striking differences in survival according to mitotic rate (<2/mm2 for pT1a or pT2a versus {greater than or equal to}2/mm2 for pT1b and pT2b). (G, H) Combining the above observations together, we concluded that tumor thickness of 2.0 mm represented the ideal cut off to combine with mitotic rate (with <2/mm2 versus {greater than or equal to}2/mm2 as the cut off) to most effectively delineate DSS among patients with PVM. (G) Schema for the proposed T-category and (H) Kaplan-Meier plots of disease-specific survival according to proposed T-categories. (Note: part G and H are identical to Figure 3C and 3D and are only shown here for direct comparison).