A uniform and rational analysis of growth rates of experimental tumors would greatly facilitate interpretation and comparison of many studies of basic tumor biology. Comparative analysis of spontaneous human tumors tends to be handicapped by wide variation in growth rates. However, animal tumors, and especially transplanted tumors, lend themselves well to group analysis.
Widely varying methods of recording are apparent in published studies of tumor biology and of effects of various experimental treatments. Some of the criteria which have been used in assessing growth rates are: (1) volume of tumors, derived from external measurements; (2) weight or volume of excised tumors; (3) volume of ascites cells, centrifuged; (4) tumor diameter, or mean diameter; (5) tracings of cross sectional areas of tumors; (6) calculated doubling time during the interval of observation; (7) calculated number of volume doublings in X time; (8) coefficient of volume expansion per unit time; (9) time required