Posted : Wednesday Jul 22, 2009 14:14:01 EDT
A new study shows that while active-duty service members have lower rates of cancer overall than civilians, they have higher rates of breast cancer and double the rates of prostate cancer.
And though that could be attributed in part to early screening efforts, the authors suggested prostate cancer rates have gone up as a result of troop exposure to depleted uranium, while breast cancer rates may have risen because military women are more inclined to use birth control pills and be exposed to industrial chemicals at levels most civilian women avoid.
In the June edition of Cancer Epidemiology Biomarkers & Prevention, lead writer Kangmin Zhu, of the Uniformed Services University of the Health Sciences, and colleagues stated that they wanted to find out if regular exercise and good health care, combined with a population that had been screened for major health issues, would yield lower rates of cancer.
They also wondered whether service members, who smoke at higher rates than civilians do, would have a higher rate of lung cancer. And the researchers also wanted to see whether sun exposure, as well as other deployment exposures such as immunizations and depleted uranium, would influence results.
But looking at the years 1990 to 2004, they found that colorectal cancer rates were “significantly lower” in the military population for white men; lung cancer rates were lower for white and black men, as well as white women; and cervical cancer rates were lower in black women.
However, breast and prostate cancers for military personnel were “significantly higher” among whites and blacks. Prostate cancer increased over that time for both the civilian and military populations, but the civilian rate doubled, while the rates for white male troops tripled.
Researchers again reasoned that this may be because of early screening — the cancer is being identified early.
“Several studies have now confirmed that cancer screening is associated with increases in breast and prostate cancer incidence rates,” Zhu wrote.
But there may be other reasons: A recent study shows 34 percent of female service members use oral birth control pills, compared to 29 percent of the general population. The pills have been linked to breast cancer.
“Military women are also more likely to be engaged in industrial jobs than females in the general population and hence potentially more likely to be exposed to chemicals that may be related to breast cancer,” Zhu wrote.
A study of military women 34 and younger find higher breast cancer rates than civilians, and the rate was even higher for those military women exposed to volatile organic chemicals as part of their work.
Zhu also linked prostate cancer to exposure.
“Although the results have been inconsistent, depleted uranium has been suggested to increase the risk of prostate cancer,” Zhu wrote. “Because military personnel are more likely to be exposed to depleted uranium, these factors may have contributed to the increased risk for prostate cancer in military members, although most of the elevated rates and more dramatic increase over time in rates in military personnel may be attributed to screening in the population.”
Testicular cancer rates were about the same for both populations.
Zhu reasoned that some cancer rates might be lower because service members are more likely to go in for cancer screening because they have free health care. Precancerous lesions and polyps might be treated early. Colorectal cancer rates may be lower for troops because they are less likely to be overweight and are more physically active.
Researchers were surprised to find, however, that lung cancer rates were lower in the military in all groups except black women. Troops smoke more than civilians do, but the researchers said service members are more likely to begin smoking as adults — rather than in their teens, as civilians tend to do.
“Cigarette smoking is the single most important risk factor for lung cancer,” Zhu wrote. “Therefore, the lower rate of lung cancer in military personnel is an unanticipated finding.”
The researchers used data from the military’s Automated Central Tumor Registry, as well as the civilian Surveillance, Epidemiology and End Results program for the National Cancer Institute. They adjusted the civilian data to include only those age groups one might expect to find in the military.
The full report is available online.