Five days after her surgery for breast cancer, Nancy Reagan kicked up her heels at a jazzy White House homecoming yesterday while an ebullient President Reagan showed her off to a crowd waving welcome-home banners and colored balloons.

"Thank you very, very much. I'm very touched ... and I'm very, very happy to be home -- very," Mrs. Reagan said after hesitating briefly when Reagan thrust a microphone in front of her.

"In view of all this, I'm trying to see if I can't scare up something that I can stay in the hospital for," Reagan joked, watching with the first lady from the Truman balcony as hundreds of balloons floated skyward in the crisp autumn sunshine.

Mrs. Reagan didn't think it was funny, however, and shook her head "no." A negative murmur also rippled through the crowd and someone softly called out "boo."

Reagan brought Mrs. Reagan home from Bethesda Naval Medical Center by helicopter, landing on the South Lawn, where White House staff, foster grandparents and "Just Say No" children had been gathered to greet her with flowers and homemade signs saying "Glad You're Back" and "Just Say No Kids Love You."

"The F.L.'s going to love this," said one White House staffer, eyeing the first lady's rooting section.

Irene Givons, a foster grandmother, was the first one to the helicopter, with a bouquet of pink roses. Mrs. Reagan took the flowers and then, seeing young Justin Sherlock, gave him a kiss.

"The foster grandparents and the 'Just Say No' kids were her good luck charm. The last time she saw them was the day she went to the hospital," said Elaine Crispen, Mrs. Reagan's press secretary.

Adding to the carnival atmosphere was the red-coated Marine Jazz Band playing medleys of songs including "Ain't She Sweet," "That's My Baby" and "Muskrat Ramble." When it struck up "Charleston," Mrs. Reagan grinningly looked back over her shoulder, kicked up her right heel and did an exaggerated circular motion with her right hand.

"Apparently, she was accepting the president's invitation to dance, after all," said Crispen, a reference to Reagan's quip when Mrs. Reagan regained consciousness after breast cancer surgery: "Honey, I know you don't feel like dancing, so let's hold hands."

A small cancerous lesion in Mrs. Reagan's left breast was detected during a routine mammography on Oct. 5. Her doctors have said her prospects of full recovery are excellent since the cancer had not spread.

Jack Courtemanche, the first lady's chief of staff, handed her a scroll bearing 1,200 signatures yesterday. Once she settled down in the upstairs family quarters, more mail and flowers awaited her, bringing the total number of cards, letters, telegrams and greetings to 5,600 from the general public, nearly 300 from personal friends and 40 from heads of state, according to the White House.