When Ronald Brown first began riding in the Pan Mass Challenge (PMC), he was 56 years old. That was in 1993, when he was challenged by a business colleague to get in shape, ride alongside him for 192 miles and raise money for a great cause – cancer research.

Brown, who runs a real estate company, took up the challenge and has been riding and raising money for cancer ever since. This past week, Brown, at 81, completed his 23rd Pan Mass two-day bicycle ride and became the oldest of the 6,200 riders to complete the grueling 192-mile route from Sturbridge to Provincetown.

To date, Brown, has raised more than $200,000 for cancer research. He noted that the PMC organization, which raised $47 million last year and hopes to raise $48 million this year, donates 100 percent of every rider-raised dollar to the Dana Farber Cancer Research Institute in Boston.

“One bike, one person, can only do so much,” Brown said in a statement, “ but 6,200 riders, along with so many volunteers and supporters, can change the whole world, putting millions of dollars in the hands of researchers, nurses and doctors who are working toward a cure. I am proud and humbled just to be a part of this monumental effort.”

To train for the PMC Challenge, Brown rides his Trek Madone racing bike on weekends from his Brookline home to the town of Weston, a distance of 30-60 miles, depending on the route. Brown also enjoys riding the 32 miles around the perimeter of Nantucket Island, catching the views of the ocean along the way.

Brown spends most of his time as president of R Brown Partners, a real estate management company, which he founded in 1985. The Brookline-based company manages more than 1,000 condominiums and apartments in 40 developments in the metro Boston area.

Brown and his better-known brother, Harold Brown, founder and chairman of The Hamilton Co., are also general partners of New England Realty Assoc., a publicly traded company that owns 2,632 apartments, 19 condos, 773 investment units and 108,000 square feet of commercial space.

Billy Starr, founder of the Pan Mass Challenge, noted that Ronald Brown, in addition to being this year’s oldest long-distance rider, is one of only 400 riders that have biked the 192-mile route from Sturbridge to Provincetown for more than 20 years.

“Ronald Brown leads by example and illustrates the fidelity of the individuals who participate in this important cause, the battle to defeat cancer,” Starr said in a statement.

Brown said funding research at Dana Farber is more important than ever, not only to the “quality of life we all aspire to, but to the core values of compassion and community that we all embrace.”

“We in the PMC world share a common goal of a world without cancer. No one chooses cancer but, if it should enter your life, or that of a family member, friend or co-worker, thank goodness for the PMC,” he said in a statement.