Ovarian cancer, a type of cancer that begins in the ovaries, can manifest with a variety of symptoms that are often subtle and easily mistaken for less serious conditions. Among these, changes in bowel habits, including diarrhea, are frequently reported by individuals with the disease. Understanding the mechanisms connecting ovarian cancer to gastrointestinal disturbances clarifies why this symptom occurs. Diarrhea in ovarian cancer is not always straightforward, arising from direct physical interactions of the tumor with the digestive system, the release of specific chemical signals, or effects on nervous system pathways that regulate bowel function.
Direct Tumor Interaction with the Bowel
The physical presence and growth of an ovarian tumor can directly influence bowel function, leading to diarrhea. As the tumor expands within the abdominal cavity, it can press on adjacent segments of the bowel, such as the small intestine. This external compression can cause a partial obstruction, leading to liquid stools or diarrhea passing around the blockage.
Ovarian cancer cells can also spread to the peritoneum, the thin lining of the abdominal cavity, a condition known as peritoneal carcinomatosis. This spread can inflame the bowel surfaces and disrupt their normal functioning, leading to altered motility and absorption, which contributes to diarrhea. Fluid accumulation in the abdomen, called ascites, further exacerbates pressure on the intestines and contributes to bowel dysfunction. In some instances, cancer cells may directly invade the bowel wall, impairing its function and contributing to diarrheal symptoms.
Inflammatory and Biochemical Signaling
Ovarian cancer can cause diarrhea through the release of various chemical substances. Both the cancer cells themselves and the body’s immune response to the tumor can produce inflammatory mediators, such as cytokines and prostaglandins. These substances can significantly alter the gut’s normal processes, influencing fluid secretion and absorption, or increasing the speed at which contents move through the intestines. For example, increased prostaglandins, which regulate gastrointestinal motility and fluid balance, can lead to diarrhea.
The interaction between the gut microbiome and ovarian cancer can also contribute to this inflammatory environment. Alterations in the balance of gut bacteria can influence the release of inflammatory factors, further promoting changes in bowel function. Some ovarian cancers can also trigger paraneoplastic syndromes, where the tumor produces hormone-like substances that affect distant organs. These substances, such as vasoactive intestinal peptide, can increase fluid secretion in the intestinal lining, leading to watery diarrhea.
Nerve Pathway Involvement
Ovarian cancer can also affect the nervous system pathways that regulate bowel function, contributing to diarrhea. Tumors can directly infiltrate or compress nerves that supply the digestive tract, disrupting the precise signaling required for normal intestinal movement and function. This interference can lead to disorganized contractions or increased motility, resulting in diarrheal episodes. Damage to these nerve pathways impairs the coordinated muscular actions that propel food through the intestines.
Paraneoplastic syndromes associated with ovarian cancer can also involve the nervous system. In these conditions, the immune system, while fighting cancer, mistakenly attacks healthy nerve cells, including those controlling involuntary gut functions. This autoimmune attack can lead to autonomic neuropathy, where the nerves regulating gut motility and secretion are damaged. The resulting impaired nerve control can cause an acceleration of bowel movements and altered fluid handling within the intestines, presenting as diarrhea.