This week, part way through his cross-country bicycle trek, Patrick Byrne pedaled into Utah.

As it happens, he owns a business in the Salt Lake Valley, and so, as he neared the offices of, some of his employees showed up to ride alongside him for the afternoon. Byrne told them he'd been looking forward to this leg of the trip. He finally had someone to talk to, someone to complain to about how hard it had been.

"The High Sierras were ridiculous," he said. "The Great Basin was absurd.

"I haven't taken a day off since Tahoe. I have nothing left in my muscles." His co-workers, a dozen of them, asked questions and offered lighthearted sympathy.

Byrne grinned at them. Sympathy for tired legs, he can accept.

Sympathy for cancer, though, that's something else.

Even now, after 12 cancer-free years, Byrne doesn't like to discuss seminoma, the testicular cancer that nearly killed him when he was in his 20s. Reticent though he is, he finds himself in an awkward spot, because he agreed to make this cross-country ride to raise money for cancer research.

Byrne is riding on behalf of Boston's Dana-Farber Cancer Institute. Having set out from San Francisco on Memorial Day, he plans to make it to the East Coast by Aug. 5 to join the Pan-Massachusetts Challenge, the country's oldest bicycle fund-raiser. And all along the way, part of his mission is to raise awareness of cancer.

When it comes to testicular cancer, awareness is important. Such cancer is fairly rare — fewer than 7,000 Americans will be diagnosed this year — yet it is the most commonly occurring cancer in males 18 to 35. Seminoma starts out as a small, painless lump. If it is found in this early stage, the cure rate is 95 percent.

Byrne's cancer was not found early, however. It had metastasized to his lungs.

He'd just graduated from college when he was hospitalized for the first time. Over the next three years, he couldn't help but think about what other guys his age were doing as he underwent surgeries, embolisms, endless rounds of chemotherapy and one gloomy prognosis after another.

He never wanted to be a poster boy for cancer, Byrne says. "There are other things in my life I'd rather be known for." Over the years, he's turned down lots of invitations to speak about it.

And yet, this past spring, when a man named Billy Star called from Dana-Farber, Byrne said yes. Star convinced him that other people with late-stage cancer needed encouragement to keep fighting.

Byrne figured he could do the biking part; since his recovery from cancer, he's ridden across country no fewer than three times. What scared him was the talking. Before he set out on his ride, he gave a speech to 500 of Dana-Farber's donors. Byrne offered $1 million of his own money if they, between them, could come up with $11 million. At one point in his speech he told them that one of the reasons it is hard to talk about his personal triumph is that he knows that death always wins the last round.

Looking back on that speech, Byrne says he will never do something so painful again. He repeats his vow, "Never again."

Of course he used those exact words after each of his three previous cross-country bike trips: "Too hard. Never again."