Brendon Allen, 28, rides his bike up to 20 miles on a given day and works more than 40 hours some weeks as a software engineer for Netopia in Lawrence.

It’s an active lifestyle that takes energy and endurance – two things Allen didn’t have a lot of just months ago. Last year, doctors diagnosed him with osteosarcoma, a type of bone cancer.

The cancer forced him to go through a harsh regimen of chemotherapy and the amputation of his right leg from the shin down.

“When I was in the depths of it (treatment), I wondered if I would ever feel normal again,” Allen, of Lawrence, said Thursday. “I don’t know if I exactly feel normal yet, but it’s a lot closer than I would have ever thought I could be after a year.”

Allen and his wife, Peony, will participate in Lawrence’s Relay for Life at 7 tonight at the Free State High School track. The event is an annual fundraiser for the American Cancer Society. The money raised supports cancer research and patient support programs.

Cancer survivor Brendon Allen, 28, will participate in tonight's Relay for Life, an annual fundraiser for the American Cancer Society, at Free State High School. Allen was diagnosed with bone cancer, forcing him to undergo intensive chemotherapy and the amputation of his right leg from the shin down.

Seventy-four teams and about 1,000 people are involved with this year’s event, said co-chairwoman Cris Aiken.

“We’re pretty darn sure we’re going to reach our goal of $118,000,” she said. “We’re about a couple of hundred dollars short right now and not everything is in.”

Allen is in good shape now, but doctors continue to monitor him.

“He’s really an inspiration,” Mick Allen, a Lawrence attorney, said of his son. “I can’t think of any situation that he now could be confronted with that will intimidate him at all. He’s just unstoppable.”

Life was a living hell after Brendon’s diagnosis, Mick Allen said.

“It’s not the natural order of things to be concerned about your son,” he said. “This cancer was rapidly expanding. The chemo was very strong. It was almost more dangerous than the illness.”

Brendon Allen contracted a bacterial infection while receiving chemotherapy. The infection caused him to be placed in intensive care at the hospital.

Doctors also had thought they could save Brendon’s leg. But the cancer was moving too fast. His bones were degenerating and reconstructing his leg wouldn’t be an option. After getting a second opinion, Brendon decided to have his leg amputated from the shin down.

“I had mixed feeling on it,” he said. “I was upset. But I was more focused on battling the cancer. For me, this meant they were going to be getting the cancer. It was a life-and-death decision.”

Brendon now has a temporary prosthetic leg. He should have a permanent one by next month and hopes he can start running, an activity he once did daily.

But for now, he said he hoped that when people saw him riding his bike that it motivated or inspired them.

“I would ride anyway,” he said. “I don’t know why I got cancer. I’ve always been healthy and exercised. But people should make sure they do what they can to be healthy and make sure their family is healthy, too.”