By Marty Graham

SAN DIEGO (Reuters) - A woman with amnesia who has been undergoing cancer treatments since she was found semiconscious in Southern California has turned to social media and law enforcement as she struggles to rekindle memory of her own identity and any family she may have.

Sam, as she is known, is white, about 50 years of age and speaks French and English with a British or Australian accent, according to police reports.

She was hospitalized after being found on a street near the beach in Carlsbad, California, about 30 miles north of San Diego, on Feb. 1.

"The amnesia I have is called retro amnesia, and doctors have said they have seen this before with the kind of antibodies from the volleyball-sized tumor that was on my ovary," she wrote on her Facebook page.   

"I have been getting chemotherapy treatments, and have lost all of my hair ... My prognosis is not good, and I pray my family will be found soon."

She said she has dreams of New South Wales and Perth in Australia, but also has flashes of memory of being in Hawaii.

Her story has been shared more than 72,000 times on Facebook, with people from around the world picking up the thread and circulating it to others.

She has also been interviewed on local television, her information shared with the FBI and the international law enforcement agency Interpol, whose missing person's bulletin for Sam shows a woman with shoulder-length white hair propped up in a hospital bed facing the camera. The FBI confirmed to Reuters on Wednesday that Sam's Facebook page is authentic and that her story is credible.

She has been moved from the hospital to an assisted-living center in a neighboring city. Her story has been picked up by Australian news media, and Sam told a local television affiliate of NBC that her faith in God and her new community of friends are sustaining her.

"I'm hoping that someone sees me, or this (referring to the NBC story), or something on the Internet, and my family immediately says, 'There she is! There she is!'" she told the NBC affiliate earlier this week.

(Editing by Steve Gorman and Sandra Maler)