LONDON — The Princess of Wales said Friday that she is “making good progress” in her cancer treatment and will attend King Charles III’s ceremonial birthday parade on Saturday, Catherine’s first public appearance since her diagnosis.

The wife of Prince William has not made any public appearances this year. She announced in March that she was undergoing chemotherapy for an unspecified form of cancer.

“I am making good progress, but as anyone going through chemotherapy will know, there are good days and bad days,” Kate said in a statement released Friday, adding that she faces “a few more months” of treatment.

“I’m looking forward to attending The King’s Birthday Parade this weekend with my family and hope to join a few public engagements over the summer, but equally knowing I am not out of the woods yet,” Kate said.

The announcement is a significant milestone, but does not mark a return to full-time public duties for the princess. The palace issued a new photo of Kate, taken in Windsor earlier this week, showing her next to a tree, dressed casually in jeans and a blazer.

The palace said the king was “delighted” that Kate will attend Trooping the Color, also known as the King’s Birthday Parade. It is an annual military parade that marks the monarch’s official birthday in June. Charles, who also is being treated for an undisclosed form of cancer, is due to oversee the ceremony.

Kate, 42, is expected to travel in a carriage from Buckingham Palace with the couple’s children — Prince George, 10; Princess Charlotte, 9; and Prince Louis, 6 — before watching the ceremony from a building near the parade ground.