I-125 brachytherapy for prostate cancer linked to small increase in bladder cancer risk

Second primary malignancies affected 10.8% of men who received I-125 brachytherapy as monotherapy for prostate cancer, researchers reported in the April issue of Clinical Oncology.

But only bladder cancer had a small increase in risk in these patients compared with the general population, with the highest risk occurring during the first 4 years of follow-up after implant, said Dr. Ann Henry and her associates at St. James’s University Hospital in Leeds, England (Clin. Oncol. 2014;26:210-5).

The investigators studied 1,805 consecutive patients who received I-125 brachytherapy as monotherapy for localized prostate cancer from 1995 to 2006 at a single public hospital. Their mean age at treatment was 63 years (interquartile range, 58-68). The researchers defined possible radiation-induced cancers as developing at least 5 years after primary radiotherapy, and with histologies distinct from prostate adenocarcinoma. The median follow-up was 8 years with 487 patients (31%) having 10 years or more.

In all, 170 patients (10.8%) were diagnosed with second primary malignancies at least 1 year after I-125 brachytherapy implant, and 77 (4.9%) were diagnosed at least 5 years after implant, the investigators said. Bladder and rectal cancers were the most common, with 10-year cumulative incidences of 1% and 0.84%, respectively.

Only bladder cancer had a standardized incidence rate that exceeded that of the general population (SIR, 1.54; 95% confidence interval, 0.96-2.46). But the increase was small, and the excess risk was slightly higher during the first 4 years of follow-up (1.69; 95% confidence interval, 0.87-3.34) than during subsequent years (SIR, 1.42; 95% CI, 0.75-2.70). For this reason, the result was probably an artifact of increased urologic surveillance not caused by brachytherapy, said Dr. Henry and her associates.

"This should not act as a deterrent to patients considering low-dose-rate brachytherapy as a treatment modality for early prostate cancer," the investigators said.

The research was supported by ONCURA, which is part of GE Healthcare. The authors did not disclose any conflicts of interest.

Second primary malignancies affected 10.8% of men who received I-125 brachytherapy as monotherapy for prostate cancer, researchers reported in the April issue of Clinical Oncology.

But only bladder cancer had a small increase in risk in these patients compared with the general population, with the highest risk occurring during the first 4 years of follow-up after implant, said Dr. Ann Henry and her associates at St. James’s University Hospital in Leeds, England (Clin. Oncol. 2014;26:210-5).

The investigators studied 1,805 consecutive patients who received I-125 brachytherapy as monotherapy for localized prostate cancer from 1995 to 2006 at a single public hospital. Their mean age at treatment was 63 years (interquartile range, 58-68). The researchers defined possible radiation-induced cancers as developing at least 5 years after primary radiotherapy, and with histologies distinct from prostate adenocarcinoma. The median follow-up was 8 years with 487 patients (31%) having 10 years or more.

In all, 170 patients (10.8%) were diagnosed with second primary malignancies at least 1 year after I-125 brachytherapy implant, and 77 (4.9%) were diagnosed at least 5 years after implant, the investigators said. Bladder and rectal cancers were the most common, with 10-year cumulative incidences of 1% and 0.84%, respectively.

Only bladder cancer had a standardized incidence rate that exceeded that of the general population (SIR, 1.54; 95% confidence interval, 0.96-2.46). But the increase was small, and the excess risk was slightly higher during the first 4 years of follow-up (1.69; 95% confidence interval, 0.87-3.34) than during subsequent years (SIR, 1.42; 95% CI, 0.75-2.70). For this reason, the result was probably an artifact of increased urologic surveillance not caused by brachytherapy, said Dr. Henry and her associates.

"This should not act as a deterrent to patients considering low-dose-rate brachytherapy as a treatment modality for early prostate cancer," the investigators said.

The research was supported by ONCURA, which is part of GE Healthcare. The authors did not disclose any conflicts of interest.

Second primary malignancies affected 10.8% of men who received I-125 brachytherapy as monotherapy for prostate cancer, researchers reported in the April issue of Clinical Oncology.

But only bladder cancer had a small increase in risk in these patients compared with the general population, with the highest risk occurring during the first 4 years of follow-up after implant, said Dr. Ann Henry and her associates at St. James’s University Hospital in Leeds, England (Clin. Oncol. 2014;26:210-5).

The investigators studied 1,805 consecutive patients who received I-125 brachytherapy as monotherapy for localized prostate cancer from 1995 to 2006 at a single public hospital. Their mean age at treatment was 63 years (interquartile range, 58-68). The researchers defined possible radiation-induced cancers as developing at least 5 years after primary radiotherapy, and with histologies distinct from prostate adenocarcinoma. The median follow-up was 8 years with 487 patients (31%) having 10 years or more.

In all, 170 patients (10.8%) were diagnosed with second primary malignancies at least 1 year after I-125 brachytherapy implant, and 77 (4.9%) were diagnosed at least 5 years after implant, the investigators said. Bladder and rectal cancers were the most common, with 10-year cumulative incidences of 1% and 0.84%, respectively.

Only bladder cancer had a standardized incidence rate that exceeded that of the general population (SIR, 1.54; 95% confidence interval, 0.96-2.46). But the increase was small, and the excess risk was slightly higher during the first 4 years of follow-up (1.69; 95% confidence interval, 0.87-3.34) than during subsequent years (SIR, 1.42; 95% CI, 0.75-2.70). For this reason, the result was probably an artifact of increased urologic surveillance not caused by brachytherapy, said Dr. Henry and her associates.

"This should not act as a deterrent to patients considering low-dose-rate brachytherapy as a treatment modality for early prostate cancer," the investigators said.

The research was supported by ONCURA, which is part of GE Healthcare. The authors did not disclose any conflicts of interest.