HARRISBURG -- Lt. Gov. Catherine Baker Knoll says she hasn't missed a session of the state Senate since she took office in January 2003, and she's not going to let a cancer diagnosis mar her perfect record.

Mrs. Knoll, 77, a McKees Rocks native and lifelong Democratic Party activist, released a letter last night saying she's getting treatments for a form of cancer she called neuroendocrine illness.

"Let me make it clear: I am being treated for cancer," she said in a letter addressed to "Pennsylvanians and Friends Beyond Our Borders."

About the cancer, she said, "I'm going after it aggressively. I have been undergoing treatments, as prescribed by my physicians. Much to the surprise of my family and close friends, I'm being obedient, doing what the doctors tell me to do."

She said that so far, "the results are encouraging ... The doctors say I'm responding well ... The outlook is good. I'm optimistic. Most of all, I feel fine and I anticipate resuming a full work schedule."

Mrs. Knoll, a former state treasurer who is in her second four-year term as lieutenant governor, was first diagnosed with cancer in early July. She said in the letter that she expects to resume her principal duty -- presiding over the Senate -- once legislators return here in mid-September.

"I will be there, gavel in hand," she vowed. She also plans to handle her jobs as chairwoman of the state Board of Pardons, the Pennsylvania Emergency Management Council and the Local Government Advisory Committee.

A longtime friend, former Pittsburgh Mayor Sophie Masloff, said she'd heard about Mrs. Knoll's illness in a TV news report last night.

"God knows we wish her the best. She's one of the old-time Democrats. There aren't many of us left. I was very sorry to hear about this, but she's a fighter and she will beat this, one way or another. We old gals have unlimited possibilities," said Mrs. Masloff, 90.

Mrs. Knoll has long had deep political support among elements of the Democratic Party, especially among women and senior citizens. She won her first term as lieutenant governor in 2002, defeating eight other Democrats -- all men -- in the May primary. She was then paired to run with former Philadelphia mayor Ed Rendell, who won the Democratic primary for governor.

An aide said Mr. Rendell will address Mrs. Knoll's situation today.

Mrs. Knoll's aide, Salvatore Sirabella, said she first learned of her condition in early July.

"She is going through a series of treatments as prescribed by her physician,'' he said. "She is having treatments on an outpatient basis in Harrisburg.''

He said his boss "is confident of a full recovery. Like other challenges she's had during her life of public service, and like other people who have faced this illness, she is confronting it openly,'' he said.

"People get sick, they undergo treatment, they recover. Right now the lieutenant governor is in the treatment stage,'' he said.

Mrs. Knoll wasn't planning to attend the Democratic National Convention next week, although she had the necessary credentials.

Mr. Sirabella said she'd been thinking of giving her convention credentials to someone else, even before she learned of her cancer.

She decided to give the credentials to Susan Rutt, president of the Pennsylvania Federation of Democratic Women.

Mr. Sirabella said Mrs. Knoll has had a long association with the women's federation and "felt that this would be a good opportunity for them to be represented at the convention.''