Long-Term Gastrointestinal Side Effects After Radiotherapy For Prostate Cancer Are More Common Than Previously Reported

UroToday.com - External beam radiotherapy (XRT) in commonly employed for the treatment of localized or locally advanced prostate cancer (CaP). Despite advances such as 3-dimensional conformal radiotherapy and intensity-modulated radiotherapy, the bladder and rectum still sustain scatter radiation. Dr. Giordano and colleagues at M.D. Anderson Cancer Center, Houston report on late gastrointestinal (GI) toxicity in the July 15th issue of Cancer.

The SEER-Medicare database was used to identify 57,955 eligible patients who were age 66 years and older with a diagnosis of localized or regional CaP. Patient demographics, dates of diagnoses and extent of disease were recorded. GI diagnoses were obtained up to 60 months after diagnosis and were separated into 3 groups: patients treated with XRT, patients treated with radical prostatectomy (RP) and patients who had no local therapy.

GI diagnoses included 1) any GI diagnosis, 2) hospitalizations for GI diagnoses and 3) procedures for GI diagnoses. The time of GI diagnosis was split into early (within 6 months of diagnosis or treatment) and late (between 6 and 60 months).

In the patient cohort, 24,130 (41.6%) underwent XRT, 11,918 (20.6%) underwent RP, and 21,907 (37.8%) underwent neither XRT nor RP. Patients undergoing XRT were older with a greater list of comorbidities. Androgen deprivation was used in 29% of XRT patients, 12% of RP patients and 34% of patients who had no local therapy.

A marked increase in GI diagnoses was noted beginning 6 months after XRT and continuing to 18-24 months. The percentage of patients with lower GI diagnoses remained persistently higher in XRT patients for 5 years. Overall, XRT patients had an absolute increase in GI diagnoses of 19.4% in the 6-60 month interval; 51.3% in irradiated men vs. 28.6% in RP men vs. 32% in men who had neither XRT not RP. The most common GI diagnosis was hemorrhage, which was 19% higher among irradiated men. Hospitalization was required in 4.4% of irradiated men over the 60-month period, compared with 3.2% in men who had no local therapy. Endoscopies were performed in 32% of irradiated men compared with 13% of surgical patients and 12% of untreated men.

Multivariate analysis demonstrated that androgen deprivation therapy was associated with a higher hazard of any GI diagnosis and diagnoses requiring hospitalization. Older men were also at higher risk, with a 51% hazard for each 10-year increase in age. Patients with a diagnosis of diabetes or peripheral vascular disease were also at increased risk for GI diagnoses after XRT. These data suggest that GI toxicity is more prevalent than pre

viously reported and continues for at least 60 months after treatment. By Christopher P. Evans, M.D.

Cancer. 2006 Jul 15;107(2):423-32
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