Patty Gallivan has never been much of a cyclist but she plans on riding her bike all the way from Vancouver to Seattle this weekend.

The 250 kilometre trek is more than double her longest ever ride but she says she has plenty of motivation to make it to the finish line.

"My nephew, Gavin, we found out that he had cancer when he was three," she said.

"He had it in his lungs and an enlarged tumour the size of a grapefruit in his stomach. We were told he had an 80 per cent chance of surviving — and he survived."

Gavin was cancer free and his family was thrilled with his clean bill of health.

That changed two years ago when he went back for another test.

"We found out that cancer had returned and what we didn't know was that Gavin carried a mutated gene where the cancer was most likely to return to five of his major organs," Gallivan said.

"This time around, it was in his rectum and his colon."

Gavin went through several rounds of chemotherapy and had his colon and rectum removed.

Gavin, now 18, is once again cancer free but is facing a long road to recovery.

"He has what is called a J-Pouch," Gallivan said.

"They use your intestines and they create like a reservoir for his waste. It's a hard time and the whole idea of knowing that cancer may return to him again is gutting for our family."

When Gallivan received an invitation to participate in the Ride to Conquer Cancer fundraising event, she accepted immediately despite her lack of experience on a bike.

"I've heard a lot about people who've actually been through cancer or have lost loved ones," she said.

"So, I've got lots of stories to keep in mind to motivate me and I know I'm going to rock it."