R.A.S HEMAT, MB;BCh, FRCSI, DUL.
Paraneoplastic syndromes are disorders of host organ function occurring at a site remote from the primary tumor and its metastases. Paraneoplastic syndromes reflect communication between tumor cells and host cells.
RBCs circulating through the tumor vascular spaces come into direct contact with tumor cell surface and tumor cell secretions, which appear to be damaging leading to microangiopathic haemolytic anaemias.
The central area of a tumor lacks well-developed vascular systems and soon become anoxic and necrotic.
Tumors that produce parathormone-like endocrine substances must rely on normal bystander osteoclasts to dissolve osseous bone and release calcium resulting in hypercalcaemic syndromes.
Cachexia is based on the Greek words "kakos", meaning bad, and "hexis", meaning state of being. The cancer cachexia syndrome encompasses a wide range of metabolic, hormonal, and cytokine-related abnormalities that result in a wasting syndrome. The clinical manifestations, including anorexia, early satiety, weight loss, weakness, easy fatigue, impaired immune function, tissue wasting, and poor performance status. Insulin resistance state is characterised by a decreased uptake and use of glucose, especially in muscle, and a tendency towards gluconeogenesis and lipolysis. Anorexia may result from pain, mechanical obstruction of the GIT, from nausea induced by chemotherapeutic drugs, or from psychological factors.
Fever is an increase of temperature above the daily variation. Hyperthermia is the increased in core temperature due to dysregulation of normal thermoregulation. Characteristic of hyperthermia is the failure of common antipyretics to lower the increased temperature, whereas in fever antipyretics are highly effective. The acute phase response is a systemic, generalised reactions, although most disease processes that induce it are localised. The most common cause of fever in cancer patients is infection, followed by paraneoplastic syndrome, drug reaction, and rarely adrenal insufficiency. Paraneoplastic fever is most common in certain types of malignancies including Hodgkin's disease, RCC.
The most common cause of endocrine syndromes of cancers (ectopic hormone syndromes) is cancer production of protein hormones or hormone precursors. The cells of the body produce peptide hormones are derived from the neural crest embryologically share two properties: 1- peptide hormone synthesis, storage and secretion; 2- amine metabolism and uptake (APUD). Some neoplasms convert the pro-ACTH to biologically active ACTH, producing clinically apparent Cushing's syndrome. Hypercalcaemia as a manifestation of cancer is a relatively common finding. The PTH gene is located on chromosome 11. Many patients who develop hypercalcaemia do not have skeletal metastases. Bone loss due immobilisation and lack of physical activity, are common in oncology patients. Hypercalcaemia causes nonspecific neurological, musculoskeletal, cardiovascular, and GIT symptoms primarily by decreasing the excitability of nerve cells and the contractility of smooth, striated, and cardiac muscle cells.
Malignant disease is associated with a wide variety of derangements in renal function and electrolyte homeostasis. Prostate cancer, bladder cancer, RCC, and Wilms' tumor can induce membranous nephropathy.
Most often erythrocytosis is not a manifestation of solid malignancy, but rather it is a phenomenon associated with myeloproliferative disorders or as a result of a physiological compensation for hypoxaemia. Thrombocytopenia is frequently the result of antitumour therapy. The thrombotic and haemorrhagic manifestations of DIC are perhaps the most frequently troublesome paraneoplastic syndrome associated with cancer.
August, 2001
Note: The information in this article has been excerpted from the following books: urotext-ebook simplifying urology, Principles of modern urology, by Dr. R.A.S HEMAT. Permission is granted to copy and redistribute this document electronically as long as it is unmodified. This article may not be sold in any medium, including electronic, CD-ROM, or database, or published in print, without the explicit, written permission of Dr. R. A. S. Hemat.
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Dr. R.A.S HEMAT declares no conflicts of interest or financial interests in any product or service mentioned in this article, including grants, employment, stock holdings, gifts, or honoraria.
