Ms Tilberis, who was married with two adopted children, was to have been honoured on 2 June by the Council of Fashion Designers of America with its annual Humanitarian Award.
The tribute was in recognition of the book No Time to Die, which she wrote last year, describing her illness and her determination to survive. It won wide acclaim for its honesty and its call to the medical community for a better understanding of ovarian cancer.
The book also told of the other side to her life, as one of the most powerful figures in the fashion universe who counted the late Diana, Princess of Wales, and Karl Lagerfeld among her closest friends.
The Hollywood actress Meg Ryan recently unveiled plans to turn the memoir into a television movie. Ms Tilberis was first diagnosed with the disease in December 1993, shortly after leaving her job as editor of British Vogue in London and coming to New York to take control of Harper's Bazaar for the Hearst magazines. She continued to work until her death, while undergoing periodic treatment.
Ms Tilberis, who married Andrew Tilberis in 1975, told in her book how learning of her illness coincided with the hosting of a glittering party in New York to celebrate her appointment. It was, she wrote, "the best of times. Except that it was the worst of times". Of a four-week hospitalisation in New York in 1995, she said: "I was reduced to an almost animal level of survival."
Unable even to swallow, she was "struggling just to make it through the day, all privacy and dignity gone, trying to hold on to something that represented the routine of life I'd taken for granted".
Ms Tilberis came to believe her cancer was the result of powerful drugs prescribed when she underwent IVF treatment in her thirties in an effort to conceive.
She used the book to advocate new research on finding links between ovarian cancer and the IVF treatment.