As Pope Leo XIV recovers from surgery and a newly disclosed lung cancer diagnosis, his family is confronting another health battle: the pontiff's older brother is fighting a recurring form of blood cancer.
Louis Prevost, the pope's older brother, recently fell out of remission after years of treatment for multiple myeloma, his wife told CBS News. The revelation comes as the Vatican says the 71-year-old pope is recovering from surgery that led doctors to diagnose him with lung adenocarcinoma, leaving two brothers facing separate cancer battles at the same time.
Here's what to know.
What to know about Louis Prevost's cancer
Deborah Prevost told CBS News that her husband was first diagnosed with multiple myeloma in 2017 and remained
in remission for years after a stem cell transplant and treatment through a clinical trial.
But the cancer returned about three months ago, she said, and he is now participating in another clinical trial at a local hospital. She did not disclose the stage of his cancer.
Multiple myeloma is a blood cancer that develops in plasma cells, a type of white blood cell found in bone marrow. According to the Cleveland Clinic, the disease can damage bones, kidneys and healthy blood cells as abnormal plasma cells build up in the body.
Deborah Prevost said her husband and the pope spoke last week before Louis began his latest clinical-trial treatment.
"We keep praying, keeping spirits up for both of them," she told CBS News.
The Vatican has not disclosed the stage of Pope Leo's cancer or whether it has spread. Deborah Prevost said she remains hopeful the pope's cancer was caught early but has not heard whether he will need chemotherapy, radiation or other follow-up treatment.
The pope's public events have been canceled through Oct. 20 as he recovers from surgery. He is scheduled to begin an 11-day trip to Uruguay, Argentina and Peru on Nov. 6, though it remains unclear whether the visit will proceed as planned.
Louis Prevost on his brother becoming pope
Louis Prevost and his younger brother, Robert Prevost, who became Pope Leo XIV in May 2025, grew up with their brother John in the Chicago area. Leo became thefirst U.S.-born leader of the Catholic Church.
After the conclave, Louis shared stories from their childhood, recalling that his future pope brother frequently pretended to be a priest while other children played games like cops and robbers.
In an interview with ABC News, Louis said Robert even used Necco wafers to imitate distributing Communion.
Despite his brother's historic election, Louis said he still sees him as family first.
"He will always be Rob," Louis told CBS News in 2025. "If we do get over there and do get to meet him, I'm still going to treat him like my little brother."
Contributing: Reuters
Reporter Anthony Thompson can be reached at ajthompson@usatodayco.com, or on X @athompsonUSAT
This article originally appeared on USA TODAY: Pope Leo and brother both facing cancer diagnoses
