WASHINGTON (NEWSnet/AP) — A review of a Montana nuclear missile base where an unusual number of troops have been diagnosed with blood cancer has found no current risk factors that could explain it, the Air Force says.

The service has been investigating the issue since reports surfaced in January of at least nine missileers who had served at Malmstrom Air Force Base who were diagnosed with non-Hodgkin lymphoma. In the months since, more than 30 cancer cases at Malmstrom and the nation's other nuclear missile facilities, including F.E. Warren Air Force Base in Wyoming, Minot Air Force Base in North Dakota and Vandenberg Air Force Base in California have come to light.

But the medical review found that “overall, there were no factors identified that would be considered immediate concerns for acute cancer risks,” the Air Force’s 711th Human Performance Wing said in a report.

The Air Force is committed to continuing to investigate the issue and will conduct an epidemiological study of cancers within the missile community, the service said.

Missileers typically are young military officers who monitor, operate and stand ready to fire the nation's nuclear warheads — sitting alert in underground launch control centers for shifts that can last from 24 to 48 hours.

Both the launch control centers and the missile silos they oversee were built more than 60 years ago.

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