Radiation Oncology/Melanoma/Unknown Primary

Melanoma From an Unknown Primary (MUP) No primary lesion is identified in up to 20% of pts presenting w/ palpable evidence of regional metastatic melanoma. Proposed causes include: Failure to recognize a primary lesion during clinical examination Prior removal of the primary lesion during traumatic injury or by excision w/o pathologic diagnosis de novo malignant transformation of ectopic nodal melanocyte (s) Spontaneous regression of the primary lesion. John Wayne Cancer Institute, CA; 2008 (1971-2005) 18235114 -- "Improved survival after lymphadenectomy for nodal metastasis from an unknown primary melanoma." (Lee CC, J Clin Oncol. 2008 Feb 1;26(4):535-41.) Retrospective. 1, 571 patients (262 had MUP; 1,309 had MKP) who underwent regional lymphadenectomy for nodal melanoma. No evidence of distant metastatic disease (brain & body imaging available at time of diagnosis). Subjects w/o apparent primary melanoma underwent cutaneous, ophthalmologic and anogenital examination. 181 (82%) MKP and 174 (71%) MUP received adjuvant therapy. Majority were male (66%), less than age 60 (73%), and had axillary site of nodal metastasis (66%). 22% had neck nodal metastasis. Similar distribution of age, sex, # of involved nodes & decade of diagnosis between groups. Median F/U 77 mo Outcome: + Survival Median Survival 5yr OS DFS 5yr DFS MUP 165 mo 58% +/- 7% 34 mo 47% +/- 7% MKP 35 mo (p=0.006) 40% +/-7% 19 mo (p=0.066) 35% +/- 7% Conclusion: Lymphadenectomy effective. Significantly better postop OS for MUP vs MKP suggests strong endogenous immune response MD Anderson; 2006 (1990-2001) 16568458 -- "Metastatic melanoma to lymph nodes in patients with unknown primary sites." (Cormier JN, Cancer. 2006 May 1;106(9):2012-20.) Retrospective. 71 patients with MUP and control 466 patients with regional LN mets and known primary. N1b 47%, N2b 14%, N3 39%. Median F/U 7.7 years Outcome: 5-year OS MUP 55% vs. MKP 42%; 10-year OS 44% vs. 32% (SS) Adverse predictors: >50 years, male, N2b/N3 status. MUP favorable prognostic factors (HR 0.6, SS) Conclusion: Relatively favorable long-term survival compared to Stage III disease, and should be considered for Stage III adjuvant protocols