Kate Middleton attends Trooping the Colour in 1st public appearance since cancer diagnosis

Kate, the Princess of Wales, made her first public appearance Saturday since announcing in March that she had been diagnosed with cancer.

Kate joined her husband Prince William, their three children, Princes George and Louis and Princess Charlotte, as well as King Charles III and Queen Camilla and other royal family members at this year's Trooping the Colour, the annual military parade held to celebrate the king's official birthday.

Wearing a white dress with black trim by Jenny Packham and a coordinating hat by Philip Treacy, Kate rode with George, 10, Charlotte, 9, and Louis, 6, in a state carriage, the Glass Coach, down the Mall during the parade.

A video shared by Kensington Palace on social media showed Kate and her children before the parade as they prepared to enter the carriage.

Following the parade, Kate, William, George, Charlotte and Louis joined Charles and Camilla and other senior members of the royal family on the balcony of Buckingham Palace to watch the military flyover.

The last time Kate had appeared in public with members of the royal family was in December, when she joined them in attending a Christmas Day service in Sandringham.

Just weeks after that appearance, the palace announced that Kate, 42, had been hospitalized on Jan. 16, for "planned abdominal surgery," and would take time off of her royal duties to recover.

In March, Kate revealed publicly that she had been diagnosed with cancer following the surgery. The type of cancer has not been disclosed.

According to the palace, Kate started a course of preventative chemotherapy in late February.

In the first update on her health since announcing her diagnosis, Kate said Friday that she is "making good progress" as she undergoes chemotherapy but is not "out of the woods yet."

"I am making good progress, but as anyone going through chemotherapy will know, there are good days and bad days," Kate said in a written message shared by Kensington Palace. "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."

Kate said her treatment will continue "for a few more months," adding, "On the days I feel well enough, it is a joy to engage with school life, spend personal time on the things that give me energy and positivity, as well as starting to do a little work from home."

This year's Trooping the Colour -- a celebration that includes over 1,400 soldiers -- marks the second for Charles as king.

He too was diagnosed with cancer earlier this year, but has since returned to public duties.

Buckingham Palace has not shared what type of cancer the 75-year-old monarch was diagnosed with, nor what type of treatment he is undergoing.

In late April, Charles visited a cancer center in his first public royal engagement since his diagnosis.

When asked by a patient how he is doing, Charles replied, "Not too bad. It’s always a bit of a shock, isn’t it, when they tell you?," according to the U.K.'s The Telegraph newspaper.

At this year's Trooping the Colour, Charles slightly modified his role in the event by riding in the parade in a horse-drawn carriage alongside Camilla, instead of on horseback as he has in years past.