Examines differences in the biology of tumor growth and vascularization as a function of the patient's age. Use of transplantable tumor cells; Animals and cell lines; Reagents and growth factors; Tumor growth, DNA synthesis and histology; Endothelial cell differentiation in culture and angiogenesis in vivo; Image analysis; Vascularization and age; PBS-Matrigel's effect on tumor growth in vivo.