Radiation colitis explained

Specialty:Gastroenterology
Causes:Radiation therapy.

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, 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

Tenesmus or diarrhea appear to be the most common symptoms in patients with radiation colitis. Patients may also exhibit perforation or obstruction.[2]

Causes

Radiation colitis is typically brought on by radiation therapy administered to the pelvis for prostate, cervix, uterus, anus, rectum, or bladder cancers.[3]

Mechanism

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

Radiation colitis is characterized histologically by stromal injury followed by progressive fibrosis that results in epithelial atrophy and persistent mucosal ischemia.

Further reading

Notes and References

  1. Book: 480 . Odze and Goldblum surgical pathology of the GI tract, liver, biliary tract and pancreas . Odze RD, Goldblum JF . Elsevier Health Sciences . 2014 . 9781455733248.
  2. Kennedy GD, Heise CP . Radiation colitis and proctitis . Clin Colon Rectal Surg . 20 . 1 . 64–72 . February 2007 . 20011363 . 2780150 . 10.1055/s-2007-970202.
  3. Qadeer . Mohammed A. . Vargo . John J. . Approaches to the prevention and management of radiation colitis . Current Gastroenterology Reports . 10 . 5 . 2008 . 1522-8037 . 10.1007/s11894-008-0093-9 . 507–513. 18799128 . 41511848 .
  4. Bernhard . E J . McKenna . W G . Muschel . R J . Radiosensitivity and the cell cycle . The Cancer Journal from Scientific American . 1999 . 5 . 4 . 194–204 . 10439162.
  5. Jones . Blake A. . Gores . Gregory J. . Physiology and pathophysiology of apoptosis in epithelial cells of the liver, pancreas, and intestine . American Journal of Physiology. Gastrointestinal and Liver Physiology . American Physiological Society . 273 . 6 . December 1, 1997 . 0193-1857 . 10.1152/ajpgi.1997.273.6.g1174 . G1174–G1188. 9435542 .
  6. Metcalfe . Anthony . Streuli . Charles . Epithelial apoptosis . BioEssays . 19 . 8 . 1997 . 0265-9247 . 10.1002/bies.950190812 . 711–720. 8626701 .
  7. Wang . Junru . Zheng . Huaien . Sung . Ching-Ching . Richter . Konrad K. . Hauer-Jensen . Martin . Cellular Sources of Transforming Growth Factor-β Isoforms in Early and Chronic Radiation Enteropathy . The American Journal of Pathology . Elsevier BV . 153 . 5 . 1998 . 0002-9440 . 10.1016/s0002-9440(10)65741-0 . 1531–1540. 9811345 . 1853410 .