New evidence hints that fungal infections may be related to cancerous tumors.

The Scientist looks at two studies that indicate (not prove, but suggest) there may be a link between rare fungi and cancerous tumors:

One group, led by researchers at the Weizmann Institute of Science in Israel and the University of California, San Diego (UCSD), reports detecting fungal DNA or cells—typically at low abundance—in 35 different cancer types, with fungal species composition differing among them.

The discovery of fungi was “surprising because we don’t know how fungi could get into tumors,” study coauthor Rob Knight, a microbiome researcher at UCSD and a cofounder of Micronoma, which develops methods of diagnosing and treating cancer using microbial biomarkers, says in a press statement. “But it is also expected because it fits the pattern of healthy microbiomes throughout the body, including the gut, mouth and skin, where bacteria and fungi interact as part of a complex community.”

The other team, led by researchers at Duke University and Cornell University, also found evidence of fungi in multiple cancer types, and highlighted a particular association between Candida species and gastrointestinal cancers. Across various sites, “several Candida species were enriched in tumor samples and tumor-associated Candida DNA was predictive of decreased survival,” the authors write in their paper.

It remains unclear whether the fungus is playing any role in cancer pathology, and there are possible alternative explanations for the connection.

You can read more about the studies here, in Cell.