INDIANAPOLIS (AP) _ A 19-year-old woman who has spent a record 488 days in a small wooden box perched atop a telephone pole says she'll remain three-stories high for another month to raise $100,000 for cancer research.

''I'm not sure what's in store for me, but I'm getting pretty excited,'' Mellissa L. Sanders said an hour before overtaking a Canadian's record at 2 p.m. Thursday.

Miss Sanders of Tucson, Ariz., climbed the pole Oct. 26, 1986. Last week, she rode out 75 mph winds in her swaying box.

The 42-square-foot box doesn't quite have all the comforts of home, but it's almost as well-equipped. She regularly runs up $300 telephone bills, watches television and has a hair dresser who makes box calls. She bathes in a children's plastic pool.

Her stunt has required commitment and sacrifice, she said.

''I gave up a good job, visiting with friends, driving my car, walking around and all kinds of things for this,'' she said.

She plans to remain in the box another month, hoping a local radio station's support will help her raise the money necessary to meet her goal.

''I've only raised $6,000 so far. It still needs to grab people's attention,'' said Miss Sanders, whose sister, Rebecca, is a cancer patient who has been in remission four years.

''If people see it's for a good cause and take two minutes to put some money in an envelope, I could make my goal,'' she said, ''I've seen telethons do it in about five minutes.''

Even if Miss Sanders has not attained her goal when she descends on March 24, her mother, Mauri Rose Sanders, says her daughter is a winner.

''I'm proud enough to burst. I feel like we both did it,'' said Mrs. Sanders, who broke a similar record in 1959 by sitting 211 days, 9 hours and 33 minutes above another Indianapolis corner in a publicity stunt.

Indianapolis radio station WZPL-FM has joined the Sanders' effort, and morning disc jockey Steve Stiles says he expects next month's live broadcasts and other planned activities to put the fund-raiser closer to her target.

''Mellissa's commitment has never wavered, but people weren't paying any attention,'' said Stiles, who climbed the pole to visit her Thursday afternoon.