The girls, Tarni Pereira, 17, of Cleveland, and Sophia Fuller, 16, of Redland Bay, will attend the formal, and Tarni her 18th birthday celebrations, with no hair.

They have volunteered to shave their heads on March 17 as part of the World's Greatest Shave event, which raises funds for the Leukaemia Foundation.

"I am doing it because Mikayla was my best friend and Sophia is my support crew," Tarni said.

Mikayla died of of cancer related diseases on November 12, 2010, at the age of 15 .

"When I met Mikayla, when she was 12, she was on her 36th dose of chemotherapy.We became inseparable," Tarni said.

Tarni said Mikayla's death had caused her to "grow up a lot" and see things from a different perspective.

"I was the lost cause and Mikayla was always there to help me. This (shaving the head) is my way of looking for closure. You grow stronger through these events," Tarni said.

Leukaemia Foundation of Queensland acting chief executive officer Keiran Mylrea said with an average of five Queenslanders being diagnosed every day, many people would know someone who has been touched by a blood cancer.

"Your hair will grow back but your contribution to the Leukaemia Foundation will have long-lasting positive effects for blood cancer patients and their families," he said.

The foundation is a not-for-profit organisation and does not receive ongoing government funding.

It provides free practical support services to patients and their families including patient accommodation, counselling, education, transport and financial assistance. More than $1 million in funds each year is dedicated to medical research.

Will you be brave and shave? For further information, public shave locations or to sign up visit, worldsgreatest shave.com or contact 1800 500 088.