The 76-year-old novelist is being treated at Memorial Sloan Kettering Cancer Center in New York, his wife Siri Hustvedt, also a writer, said on Instagram.
"My husband was diagnosed with cancer in December after being sick for months leading up to it," she wrote.
"I live in a place that I've come to call Cancerland."
“Many people have crossed its borders, either because they are or have been sick themselves, or because they love someone, a parent, child, spouse or friend who has or had a cancer," she added.
Paul Auster is the author of more than thirty books which have been translated into more than 40 languages.
He made a name for himself in 1982 with "The Invention of Solitude", an autobiographical novel in which he tries to identify his father's personality.
The novelist broke into the international scene in 1987 with his "New York Trilogy", a noir novel inspired by the detective genre.
Ms Hustvedt did not say what type of cancer her husband has or his prognosis.
"Living with someone who has cancer and is bombarded with chemotherapy and immunotherapy is an adventure of closeness and separation," she writes.
"It's not always easy to walk this tightrope..."
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