Prognostic scoring in patients with melanoma after adjuvant isolated limb perfusion

The clinical course in melanoma is variable. The aim of the present study was to assess adjuvant isolated limb perfusion (ILP) efficacy using a surrogate comparison of observed survival versus Cochran-predicted survival.

All patients in a single university hospital with primary, non-ulcerated limb melanoma who had undergone adjuvant ILP over 10 years (1986-1995) were studied. Clinical and pathological details including follow-up and survival were prospectively recorded in a national database. All patients were risk scored, as described by Cochran et al., to yield individual survival probability at the end of 3, 5 and 10 years and this was compared with observed survival at corresponding intervals.

There were 85 patients who had adjuvant ILP for primary non-ulcerated limb melanoma. Of these, 14 deaths were observed (O) within the 10-year follow-up period. The Cochran score predicted (E) 20 deaths within 10 years (O/E ratio 0.7). The O/E ratios for deaths in the 0 to 3, 3 to 5, and 5 to 10 year intervals were 8/7.4, 5/6.0, and 1/6.5, respectively; prediction of late deaths tended to be overestimated. When patients were grouped by predicted 10-year mortality (<20%, 20-40%, >40%) the overestimation was found to occur mainly in the highest risk group: O/E ratios were 6/5.9, 6/8.4, and 2/5.6, respectively (P = 0.10, Hosmer-Lemeshow test).

The observed and expected survival in patients receiving adjuvant ILP at the end of 3 and 5 years are comparable. The Cochran scoring system overestimated deaths during the 5 to 10 year interval. It is not clear whether this observation is a consequence of ILP efficacy or inaccuracy of the Cochran score.