Olivia Newton-John

Olivia Newton-John's Grease outfit fetches $405,700 at auction

The actress' original script from the film was also among the items at the sale in Beverly Hills, California, which in total raised $2.4m.

Some of the proceeds will go towards Newton-John's cancer treatment centre in Australia.

The buyers' identities are not public.

Grease was released in 1978 and Olivia Newton-John played demure Sandy alongside John Travolta as bad boy Danny.

The infamous black outfit marked Sandy's transition from a good girl high-schooler to a sexy, leather-clad biker chick, when the couple sang You're the One That I Want in a fairground.

Olivia Newton-John opens up on her cancer 'mission'

The Grease star, 69, told Australian TV show Sunday Night she was now using medicinal marijuana and other natural remedies.

Newton-John survived her initial breast cancer diagnosis in 1992 but revealed that it had returned in 2013.

A third diagnosis, of a tumour in the lower back, was made last year.

The new diagnosis is stage 4 breast cancer that has metastasized to the spine.

In the emotional interview on Sunday Night, she said: "I'm one of millions in this fight. I shouldn't say fight... in this journey.