Are growth rates of tumors of any clinical importance?

The tumor doubling times were determined in 142 rounded pulmonary lesions of 78 patients (13 bronchial carcinomas, 7 benign pulmonary tumors, and 122 pulmonary metastases). They varied between +12 and +8863 days of tumor growth and of -1810 days of decrease in tumor mass. Forty-four percent of all pulmonary metastases doubled their volume within 60 to 250 days. The growth rates during the period of observation varied greatly in several pulmonary metastases of the same patient, even for the same solitary circular lung focus of the same person. There is no relationship between tumor doubling time and histological type of the tumor, nor between the interval between operative removal of the primary tumor and the occurrence of pulmonary metastases. In patients between the ages of 10 and 30 years only rapidly growing pulmonary metastases with a tumor doubling time of less than 60 days could be found; even though there is no proved relationship between growth rate and age. The tumor doubling time gives no useful information on the nature of a circular lung focus, and there are no clinical consequences for diagnosis.