DUSTIN Snyder was diagnosed with a rare form of cancer the day before his 18th birthday.

Doctors conducted surgery to remove an affected lung and he underwent chemotherapy, but a year later the teen was rushed to hospital with abdominal pain and discovered the cancer had spread to his stomach cancer and pelvis.

Doctors have told him there's no treatment, and that he doesn't have much time left to live.

Since he was delivered the news he has done as much living as he can, but he has one thing left on his list: to marry his high school sweetheart, Sierra Siverio.

"Sierra means the world to me. Everything," Dustin told WTSP in Tampa Bay, Florida. "Can't even describe it in words."

Dustin and Sierra's love story starts in sixth grade. "Definitely my first love," Sierra said. "For sure."

They dated but lost touch and were reunited as high school seniors. They plan to marry this Sunday.

While Dustin is currently in a hospice, his family and friends have started a GoFundMe page to help fund his one last wish to marry his sweetheart Sierra.

According to his sister Brittany, who started the page, Dustin "really wants to marry the woman that has stuck by his side through all the sleepless nights and is now dealing with knowing he will pass any time soon.

"Please let's help Dustin enjoy the rest of his life with his soulmate."

The couple's community is coming together to make the wedding special and has already donated the venue, rings and a gown for the ceremony this Sunday.

The GoFundMe account, which is still several thousand dollars short of its $25,000 goal, will help with the wedding and other costs.

"If two people love each other and they want to be together for the rest of their lives, why can't they be?" Siverio asked.

Dustin has battled synovial cancer - which doctors said has no cure - with Sierra by his side.

"She was there with me since the beginning and I couldn't imagine being with anyone else," he told local news station WTSP.