The Pan-Mass Challenge, a bicycling event that spans the Bay State to raise funds for the Dana-Farber Cancer Institute, was already two-thirds of the way to its $75 million yearly goal on its first day.

And despite the sweltering, record-breaking heat of this summer, the drive to do good kept thousands of cyclists pedaling through the first day’s course Saturday, which ended at the Massachusetts Maritime Academy in Boerne.

Last year, the event brought together 10,000 riders and volunteers and delivered a record donation of $72 million to the Dana-Farber Cancer Institute, a premier cancer research organization affiliated with Harvard Medical School, and the Institute’s Jimmy Fund, event founder Billy Starr said at a TedxBoston speaking event on Jan. 8.

It’s come a long way from its beginning in 1980, when 50 riders and volunteers amassed $10,200 for the Jimmy Fund. And it was all inspired, Starr said, due to personal loss.

“In rapid order I lost my mother, my uncle and my cousin to cancer in the 70s,” Starr said at the Tedx event. He said he initially dealt with the pain by hiking a 400-mile portion of the Appalachian Trail with friends, which inspired this challenge.

On Saturday, the organization reported that it had raised $50,354,941 of its $75 million goal.

“In PMC world, we have a tagline: ‘Closer by the mile.’ There are no overnight cures or success stories. Every worthy idea claws and scratches before it glides and soars,” Starr said. “But it’s an adventure worth chasing.”