The case of 52-year-old Chantal Sebire had drawn headlines across France and revived a national debate about the right to die.
Sebire, a former schoolteacher and mother of three, was found dead at her home in the eastern town of PlombiGeres-les-Dijon, a government official said on condition of anonymity because he was not authorized to discuss the matter publicly.
The circumstances of her death were not immediately clear.
On Monday, a court in the city of Dijon rejected Sebire's request to be allowed to receive a lethal dose of barbiturates under a doctor's supervision. It refused the request for doctor-assisted suicide because of French law and out of concern for medical ethics.
Unlike in France, euthanasia is legal in both Belgium and the Netherlands, and Luxembourg is in the process of passing a law to allow it. In Switzerland, counselors or physicians can prepare the lethal dose, but patients must take it on their own.
Sebire's case caught France's attention when the media published heartbreaking before-and-after pictures that made her suffering instantly apparent. The tumor burrowed through her sinuses and nasal cavities, causing her nose to swell to several times its original size, and pushing one of her eye sockets out of her head.
Sebire, who has children aged 29, 27 and 13, was diagnosed nearly eight years ago with esthesioneuroblastoma, a rare form of cancer. The illness had left her blind, and with no sense of smell or taste, her lawyer said. She could not use morphine to ease the intense eye pain because of the side effects.