What we know about Princess Catherine's cancer diagnosis

Catherine, the Princess of Wales, has finished chemotherapy treatment after being diagnosed with an unspecified type of cancer earlier this year.

In a video statement issued Monday, Catherine she would be focused on "staying cancer free" as she began a slow return to work in the fall. The princess began preventative chemotherapy treatment in February after major abdominal surgery in January found the presence of cancer.

Here are some explanations of terms she used to describe her condition and what we know about her diagnosis:

What kind of treatment didCatherine have?

In avideo statement in March, Catherine said she wasundergoing a course of "preventative chemotherapy" to treat her illness.

Kensington Palacesaid no additional details abouther treatment would be revealedpublicly, other than that she started it in late February.

WATCH | Catherine says she's finished her chemotherapy treatment:

Princess Catherine completes chemotherapy treatment

15 days ago

Duration 6:35

Catherine, Princess of Wales, announced Monday she has completed a course of preventative chemotherapy and will return to her royal duties in the coming months. 'Doing what I can to stay cancer-free is now my focus,' she said in a video message released by Kensington Palace.

The palace also said it would notsay whattype ofcancer was found.

"We will not be sharing any further private medical information. The princess has a right to medical privacy as we all do," the statement said.

What's preventative chemotherapy?

After successful surgery, chemotherapy is often used to help kill any undetectable cancer cells and to prevent the cancer from coming back or spreading.

"The sort of chemotherapy and the time length of treatment depends on the type and stage of cancer as confirmed by examining the cancer removed at surgery," saidLawrence Young, professor of molecular oncology at the University of Warwickin a release posted on the website of the U.K.-based Science Media Centre, which works with journalists to disseminate scientific information.

In Canada, preventative chemotherapy is often called adjuvant therapy.

What type and stage of cancer wasCatherine diagnosed with?

Traditionally, types of cancer are named after where they start in the body, according to the Canadian Cancer Society.

This could include an organ such asthe breasts for solid tumours or the blood for cancers like leukemia.

The stage of cancer takes into account where a cancer is located, its size, how far it has grown into nearby tissueand if it has spread to lymph nodes or other parts of the body.

WATCH | Kate's cancer announcement in March:

Princess of Wales says she's receiving cancer treatment

6 months ago

Duration 2:20

Catherine, the Princess of Wales, says in a video released to her social media pages that tests after her surgery revealed 'cancer had been present,' and that she is in the early stages of preventive chemotherapy.

None of this is public in Catherine's case.

In general, cure rates are higher when cancer is found at an early stage. That's whycancer specialists emphasize the importance of preventative screeningdesigned todetect cancers early or before cancer symptoms are noticeable.

Are cancers common for people of Catherine's age?

The Princess of Walesis 42.

Cancer is a disease of aging because the longer a cell has existed, the more opportunities the genes in a dividing cell have to change or mutate.

More recently, researchers around the world have documented an increase in cancers in those under 50. These are considered early-onset cancers.

A 2023 BMJ analysis suggested that the early onset of 29 different cancers had risen nearly 80 per cent globally between 1990 and 2019. The number of early-onset cancer deaths increased by almost 28 per cent.

In the U.S., a study published in JAMA Network Open also concluded a wide range of cancers among American adults under 50 had increased between 2010 and 2019, particularly among women.

Why cancers seem to be on the rise in those under 50 is not known. Cancer researchers are exploring several ideas, including changes in diet,a more sedentary lifestyle and otherenvironmental factors.

"All of these things have been studied to some extent, but there's no clear answer," said Christopher Booth, a medical oncologist at Kingston General Hospital in Kingston, Ont.

Booth said oncologists in Canada are also increasingly seeing cancer in younger adults as well.

"It remains a disease that's still highly treatable if caught at an appropriate time."

Ian Bookman, a gastroenterologist in Toronto, said the research "doesn't mean every young person needs to run out and start getting cancer screening."

How extensive wasCatherine's cancer at diagnosis?

Since we don't know what stage the cancer was that was found during Catherine's surgery, we can't say how extensive it might be.

Cancer cells grow uncontrollably and can spread, or metastasize, to other parts of the body.

Benign tumours don't spread.

Cancer cells act differently than healthy cells. Specifically, they:

• Don't die off like othercells.
• Grow more quickly than other cells.
• Bypass the immune system's defences, whichwork to keep abnormal or invading cells in check.

In her statement in September, Catherine said she was focused on staying "cancer free."

"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," she said.