CHICAGO (Reuters) - Chicago's Roman Catholic Cardinal Francis George had cancerous cells removed from his kidney and liver this week, six years after he underwent surgery for bladder cancer, the diocese said on Friday.

George, who oversees 2.3 million Catholics in the nation's third-largest diocese after Los Angeles and New York, had a procedure on Wednesday removing the cancerous cells in his kidney and a nodule on his liver.

He discussed a course of treatment with his doctors, the archdiocese said in a brief statement on its website.

George, a former president of the U.S. Conference of Catholic Bishops and a conservative who has espoused strict views on homosexuality and abortion, is 75 years old and has led Chicago's archdiocese since 1997. He is a Chicago native.

He submitted his mandatory letter of resignation to Pope Benedict when he turned 75 in January, which normally is not accepted by the Vatican for a year or two, or longer.

George contracted polio as a teenager and walks with a pronounced limp.

The archdiocese said George will be resting at home over the weekend, and will be on a retreat next week.

(Reporting by Andrew Stern; Editing by Greg McCune)