The head boy of Christchurch Boys' High School, Jake Bailey, gave an emotional speech from a wheelchair at the school's end of year assembly in 2015.

Christchurch Boys' High School's head boy Jake Bailey was given weeks to live if his cancer was left untreated.

This news was broken to the 18-year-old a week before he was due to deliver his final speech at the school prizegiving on Wednesday.

He did not let that get in the way of sharing inspirational words with his peers, and was wheeled on stage in his wheelchair during a surprise break from his hospital bed.

SUPPLIED Christchurch Boys' High School head boy Jake Bailey is assisted by principal Nic Hill.

It began: "I wrote a speech, and a week before I was due to deliver this speech tonight they said, 'You've got cancer'.

"They said, if you don't get any treatment within the next three weeks you're going to die. Then they told me I wouldn't be here tonight to deliver this speech."

Bailey was been diagnosed with Burkitts non-Hodgkinson lymphoma – a fast-growing form of cancer - after three weeks of tests and feeling unwell.

CBHS Jake Bailey's treatment is going well so far, a family spokesman says.

Principal Nic Hill said the "serious" news regarding its senior monitor - the school's name for head boy - had a real impact on its community.

"It's been pretty emotionally raw at school because it has been really quick."

Hill was prepared to read Bailey's speech on his behalf, until he turned up himself.

"It was great that Jake was reading it instead of me. I know how sick he is and I was amazed at how strongly he spoke."

Bailey continued to read his original speech, and despite being overcome with emotion, he never wavered - capturing the undivided attention of the crowd of teenaged boys and staff.

He said: "None of us get out of life alive, so be gallant, be great, be gracious, and be grateful for the opportunities you have."

"We don't know where we might end up, or when we might end up."

He finished with the school's motto, "Altiora Peto", which means "I seek higher things".

It was met with a warm reception from his peers, including a spontaneous haka, standing ovation, and singing of the school song.

During the haka, Bailey closed his eyes and looked up, then mouthed the words "thank you" on its completion.

Hill had been inundated with messages of support for Bailey from old boys, parents, and others directed to the prizegiving speech on You Tube.

"He is strong and there is just a spark about him. He is just rock solid, with x-factor."

Even with cancer, he felt he would be letting the school down not being there.

The school's thoughts were with him and his family during his treatment and recovery, Hill said.