Wendy Richard was planning to marry her long-term partner today, before beginning treatment for terminal cancer.
The former 'EastEnders' actress brought the date of the ceremony forward after learning the devastating news that the disease had returned.
Richard, who has beaten cancer twice previously, found the cancer had returned to her left armpit during an annual check-up in January.
It has since spread to her right kidney and her bones.
Around 60 family members and close friends are thought to be attending today’s civil ceremony and reception.
Richard has been with her partner John Burns, who is 20 years the star’s junior, for 13 years.
The wedding is thought to be taking place in a hotel in the West End of London, near to where the actress was brought up.
Richard’s former co-stars, including Barbara Windsor, are expected to attend, as well as friends such as Dale Winton.
On-screen daughter-in-law Natalie Cassidy, who played Sonia in the BBC soap, will also be there.
The actress’s beloved dog Lily, a two-year-old Cairn terrier who is the niece of Betty, Pauline Fowler’s dog in 'EastEnders', will be a special guest.
Preparations for the event have been rushed, with Richard saying just days ago that the couple had not had time to buy their outfits, order a wedding cake or flowers.
She said: “We were going to get married anyway but when we got the diagnosis we decided to push ahead and get married now. There was no rush before.”
The star said she wants to have a “pain-free” day and a laugh at the event, being featured in an exclusive deal with 'OK!' magazine.
The couple’s honeymoon, in the US, has been postponed until after Richard finishes her chemotherapy, which starts on Monday.
Richard, who played Pauline in 'EastEnders' for 21 years, has been married three times previously.
Before 'EastEnders', she became a household name in the celebrated sitcom 'Are You Being Served?'