Pope Leo XIV’s Brother Louis Prevost Has Cancer

Louis Prevost, the 74-year-old eldest brother of Pope Leo XIV, is currently receiving treatment for multiple myeloma at a hospital in Florida, having lost remission from a 2017 diagnosis three months ago.

Medical Status of Louis Prevost in Florida

Deborah Prevost confirmed her husband’s ongoing medical battle in an interview with CBS News on October 13, 2026. Louis Prevost was initially diagnosed with multiple myeloma in 2017. A subsequent 2019 regimen involving stem cell therapy and a clinical trial successfully suppressed the plasma cell cancer to a minimal level for several years. That remission ended three months prior to the public announcement. Louis is now participating in a new clinical trial at a hospital in Florida, according to statements reported by CBS News.

Multiple myeloma is a form of cancer affecting plasma cells in the bone marrow, with the American Cancer Society estimating approximately 36,000 new diagnoses in the United States for 2026. The disease impairs the body’s immune defenses and blood cell production. Despite the relapse, Deborah Prevost stated that her husband spoke by telephone with the pontiff the week prior to entering the hospital for his treatment.

Surgical Interventions at Policlinico Gemelli in Rome

The disclosure of Louis Prevost’s health status coincided with a major medical procedure for his younger brother, Pope Leo XIV, in Rome. On October 11, 2026, the 71-year-old pontiff announced during his midday prayer that he had a small, localized pulmonary nodule requiring surgery. On October 13, 2026, the Pope was admitted to the Gemelli hospital in Rome, where surgeons performed a 90-minute video-assisted procedure to remove the lower lobe of his right lung. Histological examination during the operation confirmed an adenocarcinoma, a glandular cell lung tumor.

Robert Francis Prevost Comes from a Multicultural Catholic Family

The brothers grew up in Dolton, a suburb south of Chicago, Illinois, alongside another brother, John Joseph. Born to parents Louis Marius Prevost and Mildred Martínez, the siblings were raised in a devout Catholic household. Genealogical research reveals a diverse multicultural ancestry for the family, spanning French and Italian roots from their paternal lineage alongside Spanish heritage from Cantabria, Galicia, and the Canary Islands, as well as Creole roots in New Orleans.

Robert Francis Prevost was elected as the head of the Catholic Church on May 8, 2025, becoming the first pope born in the United States. Following that election, Louis Prevost gained international attention, including a visit to the Oval Office where he and his wife were received by United States President Donald Trump. Now, the family simultaneously manages medical treatments across two continents as the pontiff recovers in Rome and his eldest brother undergoes clinical trials in Florida.

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