How fast do metastatic tumors grow in brain?

Yoichi Watanabe, PhD1, Erik Dahlman2

1University of Minnesota 2University of Minnesota Gamma Knife Center

Keywords: brain metastasis, natural history, Imaging, brain tumor, melanoma

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     A large number of patients with metastatic brain tumors undergo Gamma Knife stereotactic radiosurgeries (GKSRS). The treatment decision is made based on the size and number of tumors observed on pre-treatment MR or CT images. A treatment cannot be initiated immediately after the pre-treatment imaging study due to mostly logistic reasons. The treatment schedule can be optimized if we know the speed of the tumor growth prior to the scheduled treatment date.
     In this study we present the measured growth rates of metastatic tumors using the data available for Gamma Knife patients at our institution.
     Preliminary results from a study of fifty-seven patients with four different primary cancer types show a range of volumetric doubling times.
     All patients treated for GKSRS had MR imaging studies before the treatment, providing us to measure the size of tumors before the treatment at least once and at the time of treatment. The volumes of the tumors were estimated by measuring the maximum dimensions in three-orthogonal directions along with a simple mathematical formula. The growth rate/or tumor doubling time was calculated by assuming a mono-exponential growth. The data were stratified based on the primary tumor types and the location of the metastatic tumors.
       The most rapidly growing metastases came from a melanoma primary which had doubling times ranging from 2 days to 40 days with an average of 16 days. Slowest growth was seen from a renal cell carcinoma primary with a range of 5.5 days to 369 days with an average of 66.7 days. Breast cancer primaries had a range from 8 days to 115 days with an average of 23.5 days while non-small cell lung cancer primaries ranged between 4 and 140 days with an average of 41 days doubling time.
     This was a retrospective analysis.
     The growth rates of tumors could be determined with imaging and vary amongst tumor types.
     The tumor growth rates measured through this study will aid medical professionals (radiation oncologist, neurosurgeons) to make a proper decision on how soon the treatment should be initiated after the initial pre-treatment imaging study.


Project Roles:

Y. Watanabe (), E. Dahlman ()