Dr Helgi Birgisson and colleagues from Sweden analyzed subacute and late adverse effects of preoperative irradiation for rectal cancer.
The research team randomly assigned 1147 patients to preoperative radiation therapy or surgery alone in the Swedish Rectal Cancer Trial from 1987 to 1990.
Patient data were matched against the Swedish Hospital Discharge Register.
The researchers identified patients admitted to hospital after the primary treatment of the rectal cancer.
Patients with known residual disease were excluded, and patients with a recurrence were censored 3 months before the date of recurrence.
| Bowel obstruction was the diagnosis of potentially greatest importance|
|Journal of Clinical Oncology|
The team calculated relative risks with 95% confidence intervals.
The researchers found that irradiated patients were at increased risk of admissions during the first 6 months from the primary treatment.
These were mainly for gastrointestinal (GI) diagnoses.
Overall, the team noted that 2 groups showed no difference in the risk of admissions more than 6 months from the primary treatment.
However, relative risks were increased for admissions later than 6 months from the primary treatment in irradiated patients for unspecified infections.
The team also observed an increase in relative risks in these patients for bowel obstruction, abdominal pain, and nausea.
Dr Birgisson's team concluded, “Gastrointestinal disorders, resulting in hospital admissions, seem to be the most common adverse effect of short-course preoperative radiation therapy in patients with rectal cancer.”
“Bowel obstruction was the diagnosis of potentially greatest importance, which was more frequent in irradiated than in non-irradiated patients.”