Kate Middleton is undergoing preventative chemotherapy to make sure the cancer is gone and doesn't return, according to a cancer expert.

The Princess of Wales made a glowing comeback to public duties at Trooping the Colour last weekend amid her ongoing cancer treatment.

Few updates have been given on Princess Kate's condition since she announced she was diagnosed with an unspecified form of cancer and was undergoing "a course of preventative chemotherapy" in late March.

But leading oncology expert Karol Sikora has now explained Middleton's treatment and shared some insight into the toll it may be taking on the royal.

Kate Middleton
Britain's Catherine, Princess of Wales, arrives to Horse Guards Parade for the King's Birthday Parade "Trooping the Colour" in London on June 15, 2024. JUSTIN TALLIS/AFP via Getty Images

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Speaking on "The Royal Record" podcast, the British physician said that preventative chemotherapy is also known in the medical world as adjuvant chemotherapy and is given after all visible cancer cells are removed during initial treatments, such as surgery.

The goal of giving adjuvant chemotherapy is to remove the microscopic cancer cells that may have been left behind and avoid a recurrence of the cancer.

"She's having preventative chemotherapy, [which is] usually given for six months," the cancer specialist told GB News digital royal editor Svar Nanan-Sen and royal correspondent Cameron Walker. "The reason preventive, we call it adjuvant chemotherapy...is given is to reduce the risk of the disease coming back."

"So any cells that may have spread, there's nothing to see on the scans. But if we think there's a risk of the disease coming back, we give adjuvant chemotherapy," explained Sikora, who was a founder and medical director of Rutherford Health and serves as the director of medical oncology at the Bahamas Cancer Center.

According to the Mayo Clinic, adjuvant chemotherapy "treats cancer with strong medicines" that are given either through a vein or taken as pills.

Kate Middleton Catherine, Princess of Wales
Britain's Catherine, Princess of Wales, smiles inside the Glass State Coach on her way to Horse Guards Parade for the King's Birthday Parade "Trooping the Colour" in London on June 15, 2024. Henry Nicholls/AFP via Getty Images

It was revealed back in March that Middleton's cancer was discovered after she underwent "planned abdominal surgery" for an undisclosed issue that was initially believed to be non-cancerous.

Sikora noted that the surgery type suggests Middleton's cancer affects an organ in the abdomen area, which includes the pancreas, liver, stomach, uterus, and several other organs.

"She's obviously had an operation for cancer, we're told. We were asked not to speculate what it was. [It was] somewhere in the abdomen, obviously; it was an abdominal operation," he said on the podcast.

Kate Middleton
Britain's Catherine, Princess of Wales smiles as she arrives to attend the Royal Variety Performance at the Royal Albert Hall in London on November 30, 2023. DANIEL LEAL/AFP via Getty Images

A day before her Trooping the Colour appearance, Middleton gave her first update on her cancer treatment since her March announcement.

According to Princess Kate, her treatment, while going well, has had its ups and downs.

"I am making good progress, but as anyone going through chemotherapy will know, there are good days and bad days," she wrote in a letter. "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."

Middleton also said that she was "not out of the woods yet" and that she will continue undergoing cancer treatment for "a few more months."

Sikora confirmed Middleton's comments about the treatment, telling the podcast that its effects can be "unpredictable."

"The actual day of the treatments [is] usually not too bad," he explained. "The day after you feel very tired, and then it's very unpredictable."

The British Royal Family Attend The Christmas Morning Service
Catherine, Princess of Wales attends the Christmas Morning Service at Sandringham Church on December 25, 2023 in Sandringham, Norfolk. Stephen Pond/Getty Images
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