Concern is mounting in Ladera Ranch, California, after a cluster of rare cancer diagnoses prompted environmental testing and demands for answers. State health officials say no specific cause has been identified, and they have not yet determined whether local cancer diagnoses are higher than expected.

At least six children in the area have been diagnosed with Ewing sarcoma, according to federal officials and local reporting. The exceptionally rare cancer develops in bone or nearby soft tissue and primarily occurs in adolescents and young adults, according to the National Cancer Institute.

Dr. Janet Yoon, a pediatric oncologist and sarcoma specialist at City of Hope in Los Angeles, said the geographic concentration deserves attention. She also acknowledged the alarm among families confronting an uncommon disease.

"Knowing that this is a very rare cancer diagnosis amplifies the concerns," Yoon told Fox News Digital. "Anytime you hear of cases in a geographic location, it does raise some concerns ... I can completely understand why further investigation is being done."

Brody Matteson, 17, died in March 2026 from complications of treatment for Ewing sarcoma. Local reports said more families began publicly discussing rare cancer diagnoses in the community following his death.

Some residents, including Brody’s father, Dustin Matteson, have questioned whether the illnesses could be connected to herbicides and pesticides used in the community. "We don't have a clear line of evidence for pesticides, but it is one of the things that concerns us," Matteson told NBC Los Angeles in July.

The California Department of Public Health conducted a review across the county in 2024 after residents raised concerns about pesticide use and certain cancers. "That analysis did not find an unusual pattern at the county level, but the data available at the time was​ limited," the department stated on its website.

The department is conducting a second review of cancer incidence data focused on Ladera Ranch. It estimates that the assessment will be completed in fall 2026, although the timeline could change based on the review’s scope, complexity and any additional information requiring evaluation.

"At this time, our colleagues at CalEPA (California Environmental Protection Agency) and its boards, departments and offices have not identified any immediate environmental hazards," the department stated. Officials said it remains unknown whether cases of Ewing sarcoma and other cancers are higher than expected or whether environmental factors can increase the risk.

In July 2026, First Assistant U.S. Attorney Bill Essayli asked the Environmental Protection Agency to examine possible environmental factors that could have contributed to multiple pediatric cancer cases. Hundreds of residents also attended community meetings during the summer.

Ladera Ranch Maintenance Corporation, the master homeowners association for the planned Orange County community, temporarily stopped using certain landscape chemicals. The organization also created an advisory committee to examine its landscaping practices.

Residents have publicly reported diagnoses of other cancers, including glioblastoma, while the investigation has continued. The current state review has not established whether those cases are related.

On Sept. 14, California State Fullerton researchers began collecting soil and water samples from local parks. Jennifer Piazza, Ph.D., a professor in the Department of Public Health at Cal State Fullerton, assembled a research team to address environmental concerns arising from the pediatric cancer cases.

"Environmental sampling is the first step of our larger, ongoing scientific investigation," Piazza told Fox News Digital. "We are collecting soil and water samples across Ladera Ranch. They are being analyzed for heavy metals, such as arsenic and lead, as well as pesticides."

Piazza said the team expects to have results by the end of the year, but she warned against treating any findings as proof of a cancer connection. "I also want to emphasize that whatever we find does not imply causality in terms of the pediatric cancer cases in Ladera Ranch," she added.

Ladera Ranch Maintenance Corporation extended its "heartfelt compassion to the families who have been affected by these devastating illnesses" in a statement to People magazine. It said no agency had identified a specific environmental cause or linked its landscape management practices to the illnesses, and noted that it had reduced synthetic pesticide use while switching to organic pesticides.

"With Ewing sarcoma, there is no confirmed genetic or environmental cause that we know of," Yoon told Fox News Digital. "We have not found any confirmed genetic or environmental factor that increases the likelihood of developing Ewing sarcoma."

The American Cancer Society says some studies have connected occupational exposure or exposure to high levels of certain pesticides with increased risks for several cancers, although evidence differs by chemical and cancer type. It states that no known lifestyle or environmental cause of Ewing sarcoma has been identified.

Yoon said Ewing sarcoma often appears as persistent pain rather than a typical sports injury or growing pain. She encouraged families to seek medical evaluation when pain persists, worsens or interferes with normal activities, and advised that specialized cancer centers with sarcoma expertise can help secure an accurate diagnosis.