Melanoma of Unknown Primary Origin: Decreased Survival for Stage 4 Patients.
Erica C Rushing, Ralph Tuthill. The Cleveland Clinic Foundation, OH
Background: There is no consensus within the current literature on the prognostic significance of metastatic melanoma of unknown primary origin. Several studies have shown no survival advantage for patients with metastatic melanomas of unknown origin, and others have shown improved outcomes for these patients. We performed a retrospective study to determine if patients with metastatic melanoma of unknown primary origin have increased survival when compared to those with a known primary melanoma of the same stage.
Design: We conducted a retrospective analysis of patients within our institutional anatomic pathology database, with a pathologic diagnosis of “metastatic melanoma” between 1999 and 2008. 238 cases met the inclusion criteria; 199 of those had metastatic melanoma of known primary origin and 39 had metastatic melanoma of unknown primary origin. Patients were classified by the AJCC staging system (2002). The two groups were compared using the two sample T-test for continuous clinical measures, the Pearson's Chi-square or Fisher's exact test for categorical measures, and Kaplan- Meier curves with log- rank analysis for overall survival.
Results: There was statistically significant decreased survival for stage 4 melanoma patients of unknown primary origin compared to those of known primary origin (p=<.001). Stage 4 patients of known primary origin had a median survival of 20.0 months (95% CI: 14.0, 27.0) compared to those in the unknown primary group with a median survival of only 8.0 months (95% CI: 5.0, 10.0). No significant survival difference was found between the two groups for those with initial metastasis to lymph nodes only (stage 3 disease). Our study also confirmed a significant increase in survival for all patients with stage 3 disease (median survival of 69.0 months, 95% CI; 45.0, 110.0) when compared to patients with stage 4 disease (median survival of 14.0 months, 95% CI: 10.0, 20.0; p=<0.001).
Conclusions: Our study found that patients with melanoma of unknown origin had a statistically significant decreased survival for stage 4 disease when compared to those of the same stage with a melanoma of known origin. Between the known and unknown origin groups, there was no difference in survival for those that presented with initial metastatic disease to lymph nodes (stage 3 disease). All of the melanoma patients with stage 3 disease survived significantly longer than those with metastases to other organs. These findings and the mixed results of other studies suggest that more research is needed to better understand the complex nature of stage 4 melanomas of unknown primary origin.
Tuesday, March 1, 2011 9:30 AM
Poster Session III # 108, Tuesday Morning