Actual doubling time values of pulmonary metastases from malignant melanoma

The growth rate of pulmonary metastases was determined in 18 patients with pulmonary metastases from histologically proven malignant melanoma. From chest radiograms 81 metastases were measured 51 consecutive times, and 120 values for doubling time were obtained. metastases with diameters of 15.0 mm or less grew significantly faster (arithmetic mean=24.9 days) than metastases with diameters over 15.0 mm (arithmetic mean=51.0 days). The difference is statistically significant (P less than 0.050). In about one-tenth (9.2%) of all measurements the values for doubling time are considerably lengthened (arithmetic mean=182.2 days). The determination of doubling time values may be considered as a useful parameter in the selection of patients for treatment of pulmonary metastases from malignant melanoma.