The Princess of Wales says she is making “good progress” after her cancer diagnosis and will attend Trooping the Colour on Saturday.

This will be her first public appearance this year following the diagnosis, and her abdominal surgery in January.

But in a personal message, Catherine says her treatment is still ongoing and will continue for another few months.

“I am not out of the woods yet,” says the princess.

This is the most significant update on Catherine’s health since revealing in March she had cancer, in a statement written in her own words.

It is accompanied by a new photograph of the princess, taken by photographer Matt Porteous, which shows her near her home in Windsor.

But there is caution with the positive message.

“As anyone going through chemotherapy will know, there are good days and bad days,” she says.

“On those bad days you feel weak, tired and you have to give in to your body resting. But on the good days, when you feel stronger, you want to make the most of feeling well,” says the princess.

“I am learning how to be patient, especially with uncertainty. Taking each day as it comes, listening to my body, and allowing myself to take this much needed time to heal.”

For Trooping the Colour, the princess will be in the carriage parade with her children and will be part of the family group waving from the balcony of Buckingham Palace.

This event is a birthday parade for the monarch and a palace spokesman said King Charles III was “delighted that the princess is able to attend tomorrow’s events”.

The princess has also expressed her thanks for messages of public support during her illness, saying she has been “blown away” by the encouragement.

“It really has made the world of difference to William and me and has helped us both through some of the harder times,” says the message from the princess.

The princess has begun to work from home and expects to attend some events over the summer, but Kensington Palace has emphasised that this is not a full return and that plans could be changed at short notice.

Cancer Research UK thanked Catherine for sharing an update on her treatment.

“Her words will mean so much to other cancer patients going through their own experience,” the charity’s chief executive Michelle Mitchell said.

Prime Minister Rishi Sunak said people living with cancer and their families would draw “hope and inspiration” from Catherine following her statement, while Sir Keir Starmer wished the princess the “very best” as her treatment continues.