Ultrasonography as the Gold Standard for In Vivo Volumetric Determination of Chemically-induced Mammary Tumors.

BACKGROUND/AIM In this study, we evaluated the dimensions and volume of rat mammary tumors and the association of these variables with tumor invasiveness. MATERIALS AND METHODS Tumors were measured by caliper and ultrasonography. Volume was determined by water displacement and by application of four formulas using tumor length (L), width (W) and depth (D) or tumor weight. RESULTS Results confirmed the data obtained in our previous work, where we verified that mammary tumors grow as oblate spheroids. CONCLUSION The determination of mammary tumor volume by applying the formula V=(4/3)×π×(L/2)×(L/2)×(D/2) is the best way to evaluate tumor volume in vivo. Beyond volume evaluation by water displacement, the determination on the basis of tumor weight is the most accurate way to evaluate tumor volume after animal sacrifice or tumor excision. According to our results, it is not possible to predict if a tumor is invasive or non-invasive by its dimensions, volume or weight. Future work in chemically-induced mammary cancer should use ultrasonography and water displacement or tumor weight to determine tumor volume in vivo and after animal sacrifice or tumor excision, respectively.