A cancer cluster recently reported in New Hampshire has striking similarities with a group of cancers in South Georgia.

Both situations involve rhabdomyosarcoma, a rare cancer, and both have struck children.

Three childhood cases of rhabdomyosarcoma and one case of Ewing sarcoma, another rare cancer, surfaced last year in and near Ware County, in the southeast corner of Georgia. The four cases were diagnosed within two months of one another last summer, relatives and community members say.

There are only 350 new cases of rhabdomyosarcoma each year in the United States, according to the American Cancer Society. The annual incidence of Ewing sarcoma is one case per every 1 million Americans, though the figure is somewhat higher for children, according to the National Cancer Institute.

The New Hampshire report, finalized last month, said “fewer than five” pediatric rhabdomyosarcoma cases were found in a five-town area of the state over a 10-year period. That number was higher than expected, said Dr. Benjamin Chan, the state epidemiologist for New Hampshire.

“We don’t know the causes,’’ he told GHN.

Chan said the cases were determined to constitute a cancer cluster. Such clusters are typically very difficult to prove.

A cancer cluster involves a greater-than-expected number of cancer cases that occur within a group of people in a geographic area over a period of time. Cancer clusters can help scientists identify cancer-causing substances in the environment, according to the National Cancer Institute.

The Georgia Department of Public Health is investigating the South Georgia cases, but has not declared that they amount to a cancer cluster. In September, the agency said the cancers did not constitute a cluster based on officials’ initial analysis,  but reconsidered that conclusion after getting new information about the South Georgia cases.

The federal Agency for Toxic Substances and Disease Registry (ATSDR) has also joined the investigation.

A Public Health spokeswoman said last week that the agency ‘’is deeply concerned about the incidence of childhood cancers in the Waycross area and welcomes the additional resources and expertise of ATSDR in this investigation.” Waycross is the Ware County seat and the largest town in the area where the cancers have occurred.

The spokeswoman, Nancy Nydam, said Public Health epidemiologists and environmental health scientists have seen the New Hampshire report.

The Georgia agency was quick to point out that the New Hampshire report did not establish any causes of the rhabdomyosarcomas found there.

Public Health quotes the following passage from the New Hampshire report: “Assessing so many risk factors in a study of fewer than five cases is not scientifically sound and could lead to spurious associations that don’t have any actual relationship to [rhabdomyosarcoma]. Further, some of these children could have a known or unknown genetic predisposition that led to [rhabdomyosarcoma] whether or not any environmental exposures occurred. This would further complicate the analysis and reduce our ability to identify any true environmental or behavioral risk factors.”

In both New Hampshire and Georgia, community members have voiced concerns that environmental factors led to the cancers.

People in the Rye, N.H., area pointed to a nuclear power plant, a coal-fired plant, and drinking water contamination as potential factors, according to the New Hampshire report.

The childhood cancers in South Georgia have reignited fears in the community that there is a connection between the diseases and where the children live, and specifically have raised concerns about a link to the history of industrial contamination in the Waycross area.

They voice concerns about an industrial site at CSX Railyard in Waycross; the former Seven Out wastewater facility, which drew an emergency EPA cleanup; and Atlanta Gas Light’s manufactured-gas plant, which closed in 1964 and also was the subject of a contamination cleanup.

State Rep. Jason Spencer (R-Woodbine), who has helped raise the profile of the cancer situation, agreed that there are similarities between the New Hampshire and South Georgia cancers.

Based on that, he told GHN, it would appear that the Ware County/Brantley County cancers were a cluster as well.

“From an epidemiologist standpoint, you’re trying to establish a cause,’’ Spencer added.

Spencer said last week that Public Health should look back over many years to see if other rare cancers have occurred.

Joan Tibor, a community member who has tracked the area cancers, noted that the Georgia cancers occurred in a much more compressed time frame than the 10-year period studied in New Hampshire.

“If they classified that [New Hampshire] as a cancer cluster, I can’t see how they cannot classify this as a cancer cluster,” she said.

ATSDR officials will visit Waycross to talk to community members Tuesday.

“The community as a whole has a lot of problems,’’ Tibor said. “I hope that they [ATSDR] will actually listen.”