[Growth dynamics of malignant melanomas. Determination of tumor doubling time based on morphometric measurements of roentgen images of lung metastases].

On the basis of serial X-ray pictures, we studied the growth dynamics of 50 pulmonary metastases (PM) in 18 patients suffering from malignant melanoma. As all the PM investigated showed exponential growth, we concluded that the PM of malignant melanoma increased according to a continuous growth rate during the period of investigation. By regression analysis, the mean tumor duplication time was calculated in 28 metastases. The tumor duplication time varied considerably (from 9 to 298 days), the majority ranging between sexes: The mean value in male patients was 35 days, in females 36 days. Assuming a constant growth dynamics of the metastases over the entire period of observation, the exact time at which the metastases theoretically started to grow as single cells was calculated by means of regression analysis. The hypothetical lifetime of the metastases is extremely long and reaches far back into the past. Thus it may be assumed that in many cases metastatic growth begins a long time before the primary tumor is surgically removed.