LEWISTON — The Patrick Dempsey Challenge, a one-day event that drew thousands of participants and raised more than $1million, is poised to grow in the coming year.

Organizers announced their dates Thursday for 2010 — Saturday, Oct. 2 & Sunday, Oct. 3 — expanding the fundraiser to two days in hopes of drawing more people into the event. For this year’s inaugural, overwhelming demand forced organizers to cap the number of participants at 3,500.

“The last thing you want is to tell someone you can’t participate in your event,” said Mark Turcotte, a spokesman for the challenge. By expanding the event to two days, organizers hope to increase their ceiling.

“We may be able to double the amount of participants,” Turcotte said.

One surprise came from the number of people who signed on for this year’s 5K run: about 2,000. Plans call for that portion of the event to get bigger.

The broad strokes of a schedule are being created. The 5K and a new 10K walking and running event would be held on Saturday. Bicycle rides of various distances would be run on Sunday.

Challenge organizers hope to again include namesake Patrick Dempsey, a Maine native who stars in the television drama “Grey’s Anatomy.”

“He plans on being here,” Turcotte said.

He might not be the only celebrity to return. Professional cyclists George Hincapie, David Zabriskie, Stephen Roche and Ted King were part of this year’s noncompetitive ride.

“They just had a great time,” Turcotte said. “They were very interested in coming back.”

Proceeds from the fundraiser benefit the Patrick Dempsey Center for Cancer Hope & Healing at Central Maine Medical Center.

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