Chapter 24: Metabolic Effects of Tumours

Metabolic Effects of Tumours examines the diffuse endocrine system and the secretion of physiologically active amines and peptides from various cells, with a specific focus on catecholamine-secreting tumors like phaeochromocytoma and neuroblastoma. The discussion covers the synthesis and metabolism of adrenaline and noradrenaline, emphasizing the diagnostic utility of metanephrines and hydroxy-methoxymandelic acid (HMMA) in managing cases of refractory hypertension. Furthermore, the text delves into carcinoid syndrome, illustrating the conversion of tryptophan to serotonin (5-HT) and the subsequent measurement of urinary 5-hydroxyindole acetic acid (5-HIAA) for monitoring disease progression. The section on Multiple Endocrine Neoplasia (MEN) categorizes these rare familial syndromes into types 1 and 2, highlighting specific genetic mutations and the involvement of the parathyroid, pancreas, and pituitary glands. A significant portion is dedicated to ectopic hormone production, where neoplastic cells revert to a pluripotential state to secrete substances like adrenocorticotrophic hormone (ACTH), antidiuretic hormone (ADH), and parathyroid hormone-related protein (PTHRP), leading to secondary conditions such as hyponatraemia, hypokalaemia, and hypercalcaemia. Finally, the text evaluates the clinical application of various tumor markers—including prostate-specific antigen (PSA), carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), and carbohydrate antigens (CA-125, CA-15-3, CA-19-9)—stressing their role in assessing prognosis, monitoring therapeutic response, and detecting disease recurrence while acknowledging their inherent limitations in sensitivity and specificity.