Mayor Bob O'Connor
	MORE COVERAGE Local leaders say mayor's energy will help him Ravenstahl, 25, would take over if mayor can't return Tomorrow: Online discussion of mayor's medical condition with the PG's Anita Srikameswaran and Rich Lord, noon to 1 p.m.

Mayor Bob O'Connor was admitted to UPMC Shadyside this afternoon for treatment for primary central nervous system lymphoma, and the form of the disease he has was labeled "extremely rare."

The mayor will begin chemotherapy tomorrow morning, and doctors at UPMC Shadyside said late this afternoon that most patients respond to the therapy within the first several days.

Mr. O'Connor "is in no way incapacitated" and is "fully functioning," said Dr. Stanley Marks, director of clinical affairs for the UPMC Hillman Cancer Center.

Mayoral spokesman Dick Skrinjar earlier said that doctors "don't expect it to seriously affect his abilities to perform the duties of the mayor of Pittsburgh."

The diagnosis was the result of the third battery of tests conducted after Mr. O'Connor, 61, was admitted for flu-like symptoms Thursday night.

He later was diagnosed with a duodenal ulcer.

Primary central nervous system lymphoma is a disease in which malignant (cancer) cells form in the lymph tissue of the brain and/or spinal cord. Having a weakened immune system may increase the risk of developing primary CNS lymphoma, but there is no indication Mr. O'Connor had a problem with his immune system.

Hospital personnel said Mr. O'Connor has the T-cell type of the disease, an extremely rare form.

The lymph system is part of the immune system and is made up of the lymph, lymph vessels, lymph nodes, spleen, thymus, tonsils, and bone marrow, according to WebMD. Lymphocytes (carried in the lymph) travel in and out of the central nervous system. It is thought that some of these lymphocytes become malignant and cause lymphoma to form in the central nervous system (CNS).

Primary CNS lymphoma can start in the brain, spinal cord, or meninges (the layers that form the outer covering of the brain).

The mayor's physician, Dr. Bernard Bernacki, said Mr. O'Connor called his office on Wednesday complaining about stomach, head and muscle pain. The symptoms sounded similar to a viral infection, and the situation was treated conservatively.

	Steve Mellon, Post-Gazette
	Dr. Frank Lieberman spoke during a press conference today at UPMC Shadyside in which it was announced that Pittsburgh Mayor Bob O'Connor will begin treatment for a rare form of lymphoma. At left is Dr. Stanley Marks.

Mr. O'Connor called back the next day and said he was even more uncomfortable, and Dr. Bernacki sent him to the hospital.

Blood tests were normal, but gastrointestinal tests and scans of his neck and shoulder were done.

The ulcer was detected, but doctors wanted to continue with more tests involving Mr. O'Connor's headaches. A spinal tap was done.

Dr. Frank Lieberman, chief of neuro-oncology at the cancer center, said primary CNS lymphomas are rare and the form Mr. O'Connor has -- called anaplastic T-cell -- occurs in only 5 percent of those. He said fewer than 50 of the cases have been studied.

Mr. O'Connor will be treated with high doses of the drug methotrexate, and patients usually respond within the first few days, Dr. Lieberman said. He will also be treated with the drug temodar in the times between methotrexate treatments. Patients often continue to go to work during this drug regimen, he said.

The mayor has a tumor in the right frontal lobe of the brain and one in the brain stem, Dr. Lieberman said. Both are small and there are no large masses.

Dr. Marks said doctors are optimistic the mayor will react well. Surgery and radiation are not called for, he said.

Because the disease is rare and its treatment with methotrexate is relatively new, it's difficult to estimate a patient's length of survival, Dr. Marks said.

The old data indicated a survival of about four years, but Dr. Marks said doctors believe it is better than that now.

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