Prostate radiotherapy raises risk of rectal cancer
Last Updated: 2005-04-01 8:51:08 -0400

NEW YORK (Reuters Health) - Radiation therapy for prostate cancer
increases the risk of rectal cancer, researchers report. "While the
findings of our study do not suggest that prostate cancer treatment
should change, we recommend that the potential for developing rectal
cancer be included in conversations between doctors and patients," Dr.
Nancy Baxter, from the University of Minnesota in Minneapolis, said in a
statement.
The findings are reported in the April issue of Gastroenterology.
Previous reports have tied prostate radiation to pelvic malignancies,
especially bladder cancer. However, it was unclear if such radiation
increased the risk of rectal cancer.
To investigate, the researchers analyzed data from more than 85,000 men
with prostate cancer who were logged in the Surveillance, Epidemiology,
and End Results (SEER) registry between 1973 and 1994.
Although most of the men were treated with surgery alone, over 30,000
received radiotherapy. The subjects had no history of colorectal cancer
and had survived at least 5 years after being treated for their prostate
cancer.
During follow-up, 1437 patients developed colorectal cancer and the bulk
of these malignancies occurred at irradiated or potentially irradiated
sites.
Further analysis showed that radiotherapy was associated with a hazard
ratio of 1.7 for the development of rectal cancer compared with surgery
alone. In contrast, treatment with radiation was not linked to cancers
in the remainder of the colon "indicating that the effect is specific to
directly irradiated tissue," the team reports.
Based on these findings, "we recommend that men who have had prostate
radiation should be monitored for rectal cancer starting 5 years after
treatment," Dr. Baxter noted.
In a related editorial, Dr. William M. Grady and Dr. Ken Russell, from
Seattle Cancer Care Alliance, comment that the present study "highlights
the fact that as more individuals become long-term survivors of their
primary malignancies, clinicians will need to focus on the prevention or
early detection of secondary treatment-related cancers."

knowledge is power - growing old is mandatory - growing wise is optional    
"Many more men die with prostate cancer than of it. Growing old is
invariably fatal. Prostate cancer is only sometimes so."
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