Prognostic and Predictive Significance of Ki67 in Primary Non-metastatic or Recurrent Acral Melanoma: Evidence from a Multicenter Retrospective Study.

BACKGROUND: The purpose of this work was to investigate the prognostic significance of Ki67 in acral melanoma (AM). PATIENTS AND METHODS: Ki67 values in primary lesions (pKi67) of 481 patients with primary non-metastatic AM (primary cohort) from three tertiary hospitals and in recurrent lesions (rKi67) of 97 patients (recurrent cohort) were recorded. The associations of p/rKi67 with clinicopathological features and prognosis were analyzed. RESULTS: In the primary cohort, high pKi67 group tended to have more ulceration, pT4, lymph node metastasis (LNM), nodal macrometastases, and recurrence (all P < 0.05). Logistic regression analysis revealed that pKi67 was significantly associated with pT4 and LNM (P = 0.004 and 0.027, respectively). Furthermore, both 5-year overall survival (OS) and recurrence-free survival (RFS) rates in high pKi67 group were significantly worse than those in moderate and low pKi67 groups (OS 47.8% versus 55.7 versus 76.8%, P = 0.002; RFS: 27.1 versus 42.8 versus 61.8%, P < 0.001). Similarly, in the recurrent cohort, the 5-year survival after recurrence (SAR) rates in high rKi67 group was significantly worse than those in moderate and low rKi67 groups (31.7 versus 47.4 versus 75%; P = 0.026). Stratified analysis also indicated a significant survival difference among pKi67 groups within various subgroups. Most importantly, multivariate Cox analysis demonstrated that pKi67 could be independently associated with OS and RFS, as well as rKi67 for SAR (all P < 0.05). CONCLUSIONS: A high Ki67 value was significantly associated with adverse pathological and prognostic features in both primary and recurrent AM cohorts. Ki67 should be routinely evaluated to guide risk stratification and prognostic prediction.