Pope's brother also battling cancer

The wife of Louis Prevost, brother of Pope Leo XIV, has revealed her husband is battling multiple myeloma and undergoing clinical trial treatment.

Deborah Prevost, the wife of Louis Prevost, revealed on 13/10 that her husband is battling multiple myeloma, a blood cancer originating from plasma cells in the bone marrow. This news follows the Vatican's announcement that Pope Leo XIV has lung cancer and underwent surgery to remove a tumor.

Deborah did not specify the stage of Louis's illness, but stated he is participating in a clinical trial at a local hospital.

Louis Prevost, the elder brother of Pope Leo XIV, outside his home in Port Charlotte, Florida, 9/5/2025. Photo: *AFP*.

Multiple myeloma is a blood cancer characterized by the excessive growth of malignant plasma cells in the bone marrow. These cells can overwhelm and replace healthy blood cells, leading to issues such as anemia, infections, and bleeding disorders.

Tumor cells can also destroy bone tissue, causing bone pain, weakness, pathological fractures, and hypercalcemia. The disease is neither contagious nor hereditary.

Louis was diagnosed in 2017 and achieved "very low" cancer cell levels after 2019 treatment, which included stem cell therapy and a clinical trial. His disease relapsed three months ago.

Deborah did not comment on Pope Leo XIV's health, but noted that her husband and his brother spoke last week, just before Louis began his clinical trial.

"He called to let us know what was going to happen", Deborah said. "We are praying and staying optimistic for both of them."

Pope Leo XIV at Saint Peter's Square on 7/10. Photo: *AP*.

Pope Leo XIV, 71, was diagnosed with pulmonary adenocarcinoma. The Vatican has not disclosed the cancer's stage, metastasis, or details of any further procedures or treatments the Pope might undergo.

Deborah stated the family is "going through a difficult time", but expressed hope that Pope Leo's cancer is in a very early stage. She has not heard any information regarding potential radiation or chemotherapy.

Pope Leo XIV is the youngest of three brothers. His older siblings are Louis Prevost, 74, and John Prevost, 72.