Kate Middleton made her first major formal appearance since announcing that she had completed preventative chemotherapy treatment for cancer.On Saturday, the 42-year-old Princess of Wales attended the British Royal League’s Festival of Remembrance event alongside other senior royals including her husband Prince William and father-in-law King Charles III, who is currently receiving treatment for cancer. According to the BBC, Charles received a standing ovation from the crowd when he arrived at the venue.Held at London’s Royal Albert Hall, the event is part of the United Kingdom’s annual Remembrance weekend, which celebrates the members of the British and Commonwealth Armed Forces community and honors fallen soldiers.Middleton was photographed standing and clapping with her family members as they watched the commemorative concert from the royal box.The princess donned a long-sleeved black dress with a bright red poppy pin for the occasion. The flower traditionally symbolizes hope and remembrance of those lost in war. KATE MIDDLETON’S CANCER BATTLE ‘STRENGTHENED HER CHRISTIAN FAITH’: EXPERTSMiddleton paid tribute to her late mother-in-law Princess Diana through her jewelry. She wore the Collingwood pearl drop earrings as well as the sapphire and diamond engagement ring which were once owned by Diana. Kate also accessorized with a pearl drop necklace.Charles’ wife Queen Camilla was not in attendance at the event. Earlier on Saturday, Buckingham Palace announced that Camilla would miss the Remembrance weekend events as she recovers from a chest infection. “Following doctors’ guidance to ensure a full recovery from a seasonal chest infection, and to protect others from any potential risk, Her Majesty will not attend this weekend’s Remembrance events,” the statement read per People.”While this is a source of great disappointment to The Queen, she will mark the occasion privately at home and hopes to return to public duties early next week,” the statement added.LIKE WHAT YOU’RE READING? CLICK HERE FOR MORE ENTERTAINMENT NEWSPer the BBC, Middleton and Charles are also set to attend the Remembrance Sunday ceremony at the Cenotaph War Memorial in Whitehall, London, where the monarch will lay a wreath. In February, Buckingham Palace announced Charles, 75, had been diagnosed with a form of cancer and was undergoing treatment. The monarch returned to public duties at the end of April after taking a three-month break to focus on his health.In March, Middleton disclosed her own cancer diagnosis and shared that she was undergoing preventative chemotherapy. In June, she made her first public appearance since revealing that she had been diagnosed with cancer when she attended the Trooping of the Color ceremony in June.CLICK HERE TO SIGN UP FOR THE ENTERTAINMENT NEWSLETTERIn a heartfelt video shared in September, Kate revealed that she was cancer-free after completing her treatment and shared her hopes for the future.”Although I have finished chemotherapy, my path to healing and full recovery is long and I must continue to take each day as it comes,” the princess said. “I am however looking forward to being back at work and undertaking a few more public engagements in the coming months when I can.PRINCE WILLIAM, PRINCE HARRY FEUD COULD FINALLY BE RESOLVED THANKS TO PRINCESS DIANA’S FAMILY: EXPERTOver the past few months, Middleton has stepped out for a handful of public events and most recently joined William in Southport, where they met with the families of the young victims who were killed in a mass stabbing at a Taylor Swift-themed dance class in July.Earlier this week, William opened up about enduring a “brutal” year after his wife and father’s cancer diagnoses.”It’s been dreadful. It’s probably been the hardest year in my life,” William said on Thursday, according to People magazine.”So, trying to get through everything else and keep everything on track has been really difficult,” he added.”But I’m so proud of my wife, I’m proud of my father, for handling the things that they have done,” William said. “But, from a personal family point of view, it’s been, yeah, it’s been brutal.”