Is melphalan dose adjustment according to ideal body weight useful in isolated limb infusion for melanoma?

Isolated limb infusion (ILI), introduced in 1992, is a technique used to deliver regional chemotherapy to treat advanced melanoma confined to a limb. Adjusting melphalan dose according to ideal body weight (IBW) has been proposed as a method of decreasing limb toxicity without compromising outcome. The current study analyzed this proposed dose adjustment.

We reviewed 99 consecutive patients with lower extremity melanomas treated by ILI at our institution between May 1998 and February 2009. Toxicity and outcomes were tested for correlation with differences between administered dose and calculated adjusted dose, both in mg and mg/L, and with differences between actual limb volume and calculated adjusted limb volume.

The median actual body weight was 71 kg, whereas the calculated median IBW was 57 kg (p < .001). Median administered melphalan dose was 7.7 mg/L. The median calculated adjusted dose was 6.5 mg/L (range 3.2-9.3 mg/L, p < .001). None of the three aforementioned parameters correlated with either Wieberdink toxicity grade or outcome. BMI did not correlate with toxicity either. Interestingly, a higher total melphalan dose did not only correlate with higher toxicity, but also with a lower response rate.

Adjusting the melphalan dose for IBW does not appear to reduce toxicity following ILI for melanoma. The effect on outcome remains uncertain. More research is needed to optimize melphalan concentrations in individual patients during ILI to limit toxicity without compromising the response.