HAMPDEN – Brendan Shea’s friends and family hope he never again buys a new bicycle.

The 25-year-old Hampden man received his first road-racing bike as a present from the Make-A-Wish Foundation at age 12. The then-seventh-grader had just been diagnosed with leukemia.

In 2006, after being cancer-free for about 12 years, Shea used his Make-A-Wish bike to ride in the Pan-Massachusetts Challenge, a fundraising event to help cancer research and treatment at the Dana-Farber Cancer Institute in Boston.

A few months after he completed that ride, Shea was diagnosed with thyroid cancer.

Still wanting to participate in the annual fundraising effort, Shea bought a new bike for this year’s ride.

“I figured new cancer, new bike,” Shea said with a hearty laugh. “I told my friends, the next time I go buy a bike they should probably ask about my health.”

Shea will be among 5,000 cyclists from 35 states and eight countries to ride in the 28th annual event on Aug. 4 and 5. The goal is to raise $27 million for cancer research and patient treatment.

Shea will ride the 163 miles from Wellesley, Mass., to Princetown, Mass., with his team the Cancer Crushers. Riders can choose from a variety of routes, ranging from 47 to 190 miles. So far, his team of 12 has raised about $30,000, Shea said.

“It is by far the most unbelievable philanthropy event I’ve ever been involved with,” said Shea, recalling the number of volunteers and community members who support the riders.

Training time has been limited, though, since Shea has spent much of this year receiving cancer treatment.

“I don’t let a lot of things get me down,” Shea said. “There are a lot of things you can control, and a lot of things you can’t. I like to think I’m a realistic optimist.”

To make a donation on Shea’s behalf, visit www.pmc.org/egifts, click on “select one rider with one donation” and type his gift identification number, BS0123. Checks also may be sent to Pan-Massachusetts Challenge, 77 4th Ave., Needham, Mass. 02494, and write BS0123 in the memo section.