The present invention relates to the use of anti-90K monoclonal antibodies for prevention and treatment of tumors and metastases thereof. In particular, the invention relates to the use of anti-90K monoclonal antibodies able to inhibit the adhesive processes of tumor cells and angiogenesis in tumors such as breast cancer, ovarian cancer, lung cancer, gastrointestinal cancer, melanoma, lymphoma and other tumors overexpressing 90K.