Mar. 11--Tanea Staples and Aaliyah Martin lived and played in the same East Side apartment complex, attended the same elementary school and, for a year, shared the same classroom.

In June, months after meeting President Barack Obama, Tanea died of a malignant brain tumor. She was 12.

Just days before, Aaliyah told her mother that her head hurt and she couldn't see. Doctors diagnosed the same cancer, called brain-stem glioma. She is 11.

"In the beginning, I just assumed that this was something that some kids get," said Aaliyah's mother, Takisha Jacobs. "Now, I'm really not sure." At the urging of the two families, state and local health officials are starting an investigation to see whether something made both girls sick.

"When you have two cases in proximity like this, where they can see each other's back door, that's unusual," said Robert Indian, chief of the Ohio Department of Health's comprehensive cancer-control program.

At the same time, so-called cancer clusters are extremely difficult to prove. Indian said he gets calls from people concerned about cancers at least once or twice a week.

"It could be a coincidence," he said. "But we have a responsibility to check it out further."

Childhood cancer is rare in itself. Tumors of the brain and central nervous system account for about

17 percent of all pediatric cancers reported nationally, Indian said.

Brain-stem gliomas are even more rare, said Dr. Corey Raffel, chief of pediatric neurosurgery at Nationwide Children's Hospital. Two of every

1 million children in the U.S. will develop a brain-stem glioma each year, he said.

It is, however, nearly always fatal.

"If you had 100 children diagnosed with this tumor, five would still be alive after two years," Raffel said.

Indian spent about 30 minutes yesterday morning with Jacobs, asking her questions about her pregnancy with Aaliyah, the water her family drinks, and whether her daughter used a cell phone.

Indian also left behind a 19-page questionnaire that delves into medical and work history and whether the family lives near any industrial sites now or did so in the past.

Tanea's aunt, Stephanie Ivory, met Jacobs after Aaliyah's cancer was diagnosed. Ivory lives with her sister, Tanea's mother, Tonia Ivory, and helped care for Tanea. They all live in the Marsh Run Apartments.

Stephanie Ivory and Jacobs suspect that Tanea and Aaliyah developed cancer during the time they spent at Koebel Elementary School on the South Side.

Though Columbus City Schools officials closed Koebel in 2006, it was reopened in the 2007-2008 school year while Leawood Elementary was remodeled. The two girls shared the same Koebel classroom.

The school is within 2 miles of several industrial sites, a fact that both women believe plays a part.

But state and local health officials say they are far from searching for a cause. First, they have to figure out whether the two cases are linked. Indian said he'll make a recommendation after he reviews information from both families.

Dr. Mysheika LeMaile-Williams, the city's medical director, said she will examine all reported cases of childhood brain-stem glioma in Franklin County to see whether anything stands out.

Investigations such as this can take years and often end with no conclusion.

A state-led investigation of 35 childhood-cancer cases near Clyde in Sandusky County began in 2007 and is still under way. So far, air and drinking-water tests have come up empty, said Dina Pierce, spokeswoman for the Ohio Environmental Protection Agency.

And an investigation of 83 leukemia cases in Marion County ended after five years in 2001 without determining a cause. Many parents suspected that the cancers sprang from toxic waste buried at River Valley schools. River Valley students were moved to new schools in 2003.

Indian said that in the 15 years he's investigated cases such as these, he's never found a definitive link between cancer cases and any toxic substance or pollutant. He said there are so many other factors, including lifestyle choices, that make investigations difficult.

"To find it, to say, 'Aha! I've found the smoking gun!' is everyone's dream," Indian said. "It just doesn't match up to reality."

Environmental advocates disagree.

Teresa Mills of the Buckeye Environmental Network said officials don't want to link cancers to businesses.

"These studies are inconclusive by design," Mills said.

Ivory said she's convinced that Tanea and Aaliyah's illnesses are no coincidence.

"This is about finding out what's going on and what's killing the children," Stephanie Ivory said.

shunt@dispatch.com

To see more of The Columbus Dispatch, or to subscribe to the newspaper, go to http://www.columbusdispatch.com.

Copyright (c) 2010, The Columbus Dispatch, Ohio

Distributed by McClatchy-Tribune Information Services.

For reprints, email tmsreprints@permissionsgroup.com, call 800-374-7985 or 847-635-6550, send a fax to 847-635-6968, or write to The Permissions Group Inc., 1247 Milwaukee Ave., Suite 303, Glenview, IL 60025, USA.