Endangered monkey at Lincoln Park Zoo declared cancer-free after 1st-of-its-kind surgery

CHICAGO -- An endangered monkey at Chicago's Lincoln Park Zoo is now cancer-free following a first-of-its-kind surgery.

The patient is named Zhang, an old-world monkey known as a Francois langur.

The zoo's director of veterinary medicine first noticed a cancerous tumor on the roof of the primate's mouth in 2021.

The tumor is common in the species, but it is usually detected when it is too late to treat or after the monkey has died.

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Veterinarians from the zoo teamed up with Chicago's Rush University Medical Center and successfully removed the tumor in 2022.

Little Zhang had a follow-up surgery in May, and was officially declared cancer-free earlier this month.

This marks the first time a Francois langur was successfully treated for oral cancer.