While excessive or unexplained sweating is usually due to other causes, it can be a sign of several types of cancers, including: Chronic Lymphocytic Leukemia, cancer of the lymphatic system Hodgkin Lymphoma's, a cancer of the immune system Pheochromocytoma, a tumor in the center of the adrenal gland, which causes it to make too much adrenaline Tumors of the nervous and endocrine system Carcinoid t