Kate, the Princess of Wales, was absent Tuesday as members of Britain's royal family hosted one of their most decorated annual events.
King Charles III, Queen Camilla, and Prince William hosted the Diplomatic Corps reception at Buckingham Palace, where they mingled with "representatives of countries accredited to the Court of St. James," according to the palace.
Camilla wore an aquamarine tiara at the reception, held in the State Rooms of the palace.
Kate, who announced in March that she was diagnosed with cancer, did not attend the reception even as she is gradually returning to public duties.
The 42-year-old princess shared in a video message in September that she had completed chemotherapy and is now focused on staying "cancer free."
Break-in reported near Prince William, Kate Middleton's home at Windsor CastleIn October, Kate attended her first public engagement since announcing her diagnosis, when she joined William in Southport, England.
Last weekend, Kate joined royal family members at the Festival of Remembrance and at the Cenotaph War Memorial in London to mark Remembrance Sunday.
Kate has not revealed what type of cancer she was diagnosed with, nor details of her treatment, beyond saying that she underwent "preventative chemotherapy."
Kate Middleton makes 1st major public appearances since completing cancer treatmentKensington Palace announced last week that Kate will once again host her Together at Christmas Carol Service at Westminster Abbey.
This year's service will take place on Dec. 6, and air in the U.K. on Christmas Eve.