Blues lock Kurtis Haiu has started treatment for a bone tumour on his ribs and is expected to be out of rugby for at least a year.

Haiu was diagnosed with the tumour two weeks ago and a biopsy revealed the cancer had spread, meaning he faces the next three months of chemotherapy followed by surgery to have the residual tumour removed before another six months of chemotherapy.

"It's stage two cancer, which means it's spread just outside the bone and into the soft tissue, but nowhere else," Blues doctor Stephen Kara told reporters in Auckland on Monday.

"The specialist has quoted a 65 percent cure rate at five years.

"We had it down to probably four differentials and this would be the worst of those four."

Kara said the fact Haiu, 26, who has played 53 Super rugby matches for the Blues, was young and fit would help him fight the disease, which is unusual for someone of his age.

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