The city's fourth annual Relay for Life event will begin at noon.
So far, about $200,000 has been raised and organiser June Porter-Mills expected "thousands" more to come in on the day.
This year, 134 teams had entered, compared with 125 in 2007, she said. "It's just awesome."
The first lap of the 300m track is known as the survivors' lap, when cancer survivors are able to join in, wearing a purple sash.
A candlelight ceremony will be held at 9pm to remember those who have died from cancer.
Throughout the day, people can purchase candle bags, write messages on them and place them around the track.
"It's a time for remembrance of those who have died and those going through treatment," she said.
Two head-shavings will be staged during the event, at 5.30pm today and 10am tomorrow.
Martin Phillipps, from The Chills, will play at 8pm and other local acts will perform throughout the event.
All money raised will stay in the region to be used for research funding, health promotion and support.
Anyone wanting to donate to the relay can do so online at www.cancerotagosouth.org.nz/12.htm.
