Some men with prostate cancer who undergo external beam radiotherapy (EBRT), interstitial brachytherapy, or radical prostatectomy show evidence of toxicity for at least a decade after the procedure. Grant Hunter, MD, a third-year urology resident at the Cleveland Clinic in Ohio, led the retrospective study and presented findings at the meeting. He said all 3 modalities resulted in gastrointestinal (GI) and/or genitourinary (GU) toxicities up to 10 years later, with the most severe profiles observed in patients with diabetes mellitus (Table). “The findings from this study should be of special interest to oncology nurses,” said Hunter, who noted that many clinicians might not be aware of the potential for late-term effects related to these therapies.
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Hunter and colleagues reviewed records for 483 patients who received EBRT (36%), interstitial brachytherapy (24%), or radical prostatectomy (40%) for prostate cancer in 1999. They examined the incidences of late GI and GU treatment-related adverse effects during a mean follow-up of 8.6 years (range, 0.2- 11.5 years) and graded their severity according to the Radiation Therapy Oncology Group scoring criteria for acute and late effects. Other factors weighed in the analyses include patient’s age; body mass index; smoking history; and medical comorbidities, such as diabetes mellitus, peripheral vascular disease, and connective tissue disease.
The rates of late GI and GU toxicities were low, which Hunter said was reassuring. A competing risk regression analysis found that patients who underwent EBRT were most likely to experience GU toxicities ≥grade 2 in 10 years of follow-up and patients who received brachytherapy were least likely (11.2% vs 4.3%, respectively). In the 10 years after radical prostatectomy, 5.5% of patients had GU toxicities ≥grade 2. The risk of GU toxicity ≥grade 2 was 2.35-fold greater for men with diabetes at treatment outset than men who did not have diabetes when beginning therapy (P = .043).
Nobody in the radical prostatectomy group experienced late GI toxicity ≥grade 2, but the 10-year cumulative rate was 1.7 for patients in the brachytherapy arm and 7.8% for the EBRT group. According to Hunter, EBRT (P = .038) and diabetes (P = .008) were the only independent variables found to significantly increase patients’ risk of late GI toxicity of ≥grade 2.
“This is the first study of this kind to look at all 3 treatment modalities in patients treated for prostate cancer,” said Hunter in an interview with The Oncology Nurse-APN/PA. “We thought this was something to look at because patients treated for prostate cancer tend to live a very long time and so the potential toxicity profiles are relevant.”
Hunter said it is important for oncology nursing professionals to be cognizant of the possibility for patients treated 7 or 8 years ago to experience late GI and GU toxicity. These patients have a “need for follow-up and need for care because of toxicity issues that are late, especially in patients who have diabetes when they undergo treatment,” he said.