Radiation colitis
| Radiation colitis | |
|---|---|
| Specialty | Gastroenterology |
| Causes | Radiation therapy.[1] |
Radiation colitis is injury to the colon caused by radiation therapy. It is usually associated with treatment for prostate cancer or cervical cancer.[1] Common symptoms are diarrhea, a feeling of being unable to empty the bowel,[2] gastrointestinal bleeding, and abdominal pain.[1]
If symptoms of radiation colitis onset within 60 days of exposure to radiation, it is referred to as acute; otherwise, it is classified as chronic. Acute radiation colitis may onset within a few hours of radiation exposure, and may clear up within two or three months after radiation ends. Between 5 and 15% of individuals who receive radiation to the pelvis may have chronic radiation colitis.[1] Radiation therapy can also affect the bowel at the small intestine (radiation enteritis) or the rectum (radiation proctitis).[2]
Signs and symptoms
[edit]Tenesmus or diarrhea appear to be the most common symptoms in patients with radiation colitis. Patients may also exhibit perforation or obstruction.[2]
Causes
[edit]Radiation colitis is typically brought on by radiation therapy administered to the pelvis for prostate, cervix, uterus, anus, rectum, or bladder cancers.[3]
Mechanism
[edit]Radiation primarily harms rapidly dividing cells by causing DNA strand loss that results in irreversible DNA changes. Consequently, the G2/M phase of the cell cycle, when the DNA strands are arranged into well-defined chromatin pairs and prepared for division into two daughter cells, is when radiation damage is greatest.[4] Colocytes, the cells that divide quickly that make up the epithelium lining the colon, undergo regeneration every five to six days. Its quick regeneration also makes it more vulnerable to radiation-related damage.[5]
Genetic and cytokine interactions are necessary for the active process of programmed cell death known as apoptosis. Research on animals has demonstrated a significant increase in intestinal crypt apoptosis following low-dose radiation exposure.[6]
Through its strong fibrogenic and proinflammatory effects, TGF-β also plays a significant role in the pathogenesis of chronic radiation colitis. TGF-β levels in irradiated tissues are significantly higher and stay elevated in smooth muscle cells, vascular endothelial cells, and fibrocytes for up to 26 weeks.[7]
Diagnosis
[edit]Radiation colitis is characterized histologically by stromal injury followed by progressive fibrosis that results in epithelial atrophy and persistent mucosal ischemia.[3]
References
[edit]- ^ a b c d Odze RD, Goldblum JF (2014). Odze and Goldblum surgical pathology of the GI tract, liver, biliary tract and pancreas. Elsevier Health Sciences. p. 480. ISBN 9781455733248.
- ^ a b c Kennedy GD, Heise CP (February 2007). "Radiation colitis and proctitis". Clin Colon Rectal Surg. 20 (1): 64–72. doi:10.1055/s-2007-970202. PMC 2780150. PMID 20011363.
- ^ a b Qadeer, Mohammed A.; Vargo, John J. (2008). "Approaches to the prevention and management of radiation colitis". Current Gastroenterology Reports. 10 (5): 507–513. doi:10.1007/s11894-008-0093-9. ISSN 1522-8037. PMID 18799128. S2CID 41511848.
- ^ Bernhard, E J; McKenna, W G; Muschel, R J (1999). "Radiosensitivity and the cell cycle". The Cancer Journal from Scientific American. 5 (4): 194–204. PMID 10439162.
- ^ Jones, Blake A.; Gores, Gregory J. (December 1, 1997). "Physiology and pathophysiology of apoptosis in epithelial cells of the liver, pancreas, and intestine". American Journal of Physiology. Gastrointestinal and Liver Physiology. 273 (6). American Physiological Society: G1174–G1188. doi:10.1152/ajpgi.1997.273.6.g1174. ISSN 0193-1857. PMID 9435542.
- ^ Metcalfe, Anthony; Streuli, Charles (1997). "Epithelial apoptosis". BioEssays. 19 (8): 711–720. doi:10.1002/bies.950190812. ISSN 0265-9247. S2CID 8626701.
- ^ Wang, Junru; Zheng, Huaien; Sung, Ching-Ching; Richter, Konrad K.; Hauer-Jensen, Martin (1998). "Cellular Sources of Transforming Growth Factor-β Isoforms in Early and Chronic Radiation Enteropathy". The American Journal of Pathology. 153 (5). Elsevier BV: 1531–1540. doi:10.1016/s0002-9440(10)65741-0. ISSN 0002-9440. PMC 1853410. PMID 9811345.
Further reading
[edit]- Kountouras, Jannis; Zavos, Christos (2008). "Recent advances in the management of radiation colitis". World Journal of Gastroenterology. 14 (48). Baishideng Publishing Group Inc.: 7289. doi:10.3748/wjg.14.7289. ISSN 1007-9327. PMC 2778112. PMID 19109862.