Agent Orange exposure linked to prostate cancer

NEW YORK (Reuters Health) - A study of Vietnam War era veterans shows that exposure to Agent Orange is associated with more than a two-fold increased risk of prostate cancer, earlier disease onset, and prostate cancer with more aggressive features.

"Consideration should be made to classify this group of individuals as 'high risk', just like men of African-American heritage and men with a family history of prostate cancer," Dr. Karim Chamie, from the University of California Davis, Sacramento, and colleagues recommend.

As reported in the current issue of the journal Cancer, prior research established a link between Agent Orange exposure and the development of various soft tissue malignancies. The association with prostate cancer was considered to be relatively weak, but this may have been because the studies were conducted nearly a decade ago at a point when many veterans had not reached an age when prostate cancer is common.

The current investigation, by contrast, involved men entering their 60s and, therefore, had an inherently higher risk of prostate cancer. The study included 6,214 veterans exposed to Agent Orange from 1962 to 1971 and 6,930 veterans who were not exposed to the defoliant. The subjects were followed from 1998 to 2006.

Among the exposed group, 239 men were identified with prostate cancer, compared with 124 cases among the unexposed men, resulting in a more than two-fold risk in the exposed group. On average, prostate cancer developed 407 months after Agent Orange exposure, the report indicates.

Compared with those who were not exposed, men exposed to Agent Orange tended to be younger when prostate cancer was diagnosed (59.7 vs. 62.2 years) and to have a higher prevalence of high-grade (aggressive) tumors (21.8 percent vs. 10.5 percent) and a higher rate of advanced disease at the time of diagnosis (13.4 percent vs. 4 percent).

Upon additional analysis, the researchers found that Agent Orange exposure was the strongest predictor of developing prostate cancer and of having high-grade and metastatic disease at diagnosis, the authors note.

The current findings support aggressive screening for prostate cancer in these veterans to detect high-risk cancers before they spread, the authors state.

"The expansion of benefits and screening programs will place further pressures on the VA healthcare system given the current level of budgetary appropriations," they add.

SOURCE: Cancer, November 1, 2008.