How common are late side effects after radiation treatment for rectal cancer?

This study investigated the frequency of late gastrointestinal (GI) side effects after radiation therapy (RT) for rectal cancer. Researchers suggested that after the improvement of RT methods these side effects are less frequent and less severe.

Colorectal cancer is one of the most frequently diagnosed cancers in the US. Of these, 29% are rectal cancers. The standard treatment for rectal cancer is surgery followed by RT and chemotherapy. RT consists of the use of high-energy rays to damage cancer cells and stop them from growing. It is associated with side effects due to affecting not only cancer cells but healthy cells too.

Prior studies showed the side effects rates at early stages, which usually appear between weeks 1 and 3 after RT. However, too little is known about the late side effects that may appear after RT.

This study reviewed 9 other studies about RT for rectal cancer. Information about 2115 patients was analyzed.

The overall occurrence of late severe side effects was 19%. The most common side effects were diarrhea (35%), fecal incontinence (involuntary leakage of stool; 22%), gas incontinence (71%), rectal bleeding (9%), rectal pain (13%) and obstruction (7.4%).

Treatment before surgery and more advanced RT techniques resulted in lower rates of late side effects. 

This study concluded that improved RT techniques decrease the rate of late side effects after rectal cancer radiation treatment.

This study was based on information from medical records. Data may have been missing. Further studies are needed.