Princess Kate says she's receiving 'preventative chemotherapy'—here's what that means

Catherine, Princess of Wales, shocked the world in late March, 2024, when she announced that she has cancer. Though she didn't specify which type or stage, she mentioned receiving "preventative chemotherapy," an unfamiliar term to many.

Better known as Kate Middleton or Princess Kate, the British royal family member revealed in the pre-recorded video that she had undergone major abdominal surgery in January for an undisclosed condition she believed at the time to be non-cancerous. However, later tests found cancer was present, which led her medical team to suggest "a course of preventative chemotherapy," which she's now receiving.

This therapy is commonly administered to cancer patients to prevent the disease from returning after a cancerous mass has been removed surgically. Its medical term is "adjuvant” therapy, however, and most doctors don’t refer to it as “preventative” chemotherapy because doing so could cause confusion.

“There is no such thing as providing chemotherapy as a means to 'prevent' cancer in itself," says Monica Avila, an oncologist at the Moffitt Cancer Center in Tampa, Florida.

Any cancer diagnosis can be alarming since the disease is the second leading cause of death, according to data from the U.S. Centers for Disease Control and Prevention. But modern medical interventions have helped cancer death rates decrease by some 33 percent since 1991—in part because of improved screening and early diagnosis.

"Most patients are cured when early-stage cancers are discovered," says Yuman Fong, a surgical oncologist at the City of Hope cancer center in Southern California.

Of course, desired outcomes and survival rates depend on a patient's willingness to follow the treatment recommendations of their doctors—a commitment Princess Kate seems to be exemplifying.

What is preventative chemotherapy?

Cancer is a disease in which a mutation in a cell’s DNA causes it to begin growing rapidly and uncontrollably, interrupting normal functions and putting various bodily systems and organs at risk. These cancer-causing cell mutations can occur sporadically or result from lifestyle or environmental factors such as air pollutants, exposure to too much sunlight, dietary choices, or tobacco use. Research shows that genetics also plays a role in increased risk of certain cancers.

The first thing an oncologist does after cancer has been discovered in a patient is determine the safest and most effective way of killing or removing these rogue cells from the body.

Treatments include surgery, where a cancer mass is removed; radiation in which high-powered electrical or proton beams are focused on cancer cells to kill them; or chemotherapy, in which chemicals insert themselves into the DNA of cancer cells to destroy them.

Oftentimes, a combination approach is recommended. "The intent of all these treatments is to destroy cancer cells, even when they are microscopic," says Elena Ratner, a physician and gynecologic oncologist at Yale Cancer Center in Connecticut.

After surgically removing or eradicating the presence of existing cancer cells, follow-up adjuvant treatment can be administered to prevent the cancer from returning, which is what Princess Kate was likely referring to when she said she was receiving “preventative chemotherapy.”

"Adjuvant treatment is given in cancers to help to reduce the risk of recurrence and treat micro-metastatic disease," says Syma Iqbal, a physician and gastrointestinal oncologist at USC Norris Comprehensive Cancer Center in Los Angeles. After receiving a course of the treatment, she explains, "patients are subsequently monitored with scans to make sure there is not recurrence of the disease."

What are the consequences of chemotherapy?

Whether a patient is receiving chemotherapy as a way of preventing cancer from returning after a cancer mass has been removed—as seems to be the case with Princess Kate—or as a treatment to target a known presence of the disease, "the same drugs are used," says William Dahut, an oncologist and the chief scientific officer for the American Cancer Society.

These chemicals are administered orally or intravenously, either through a surgically-installed port or via a new injection site each visit. While the chemicals used are designed to target and destroy rapidly growing cancer cells, "unfortunately, chemotherapy also has an impact on other growing cells in the body, such as hair follicles, lining of the gastrointestinal system, and blood cells," explains Dahut.

Because of this, chemotherapy can harm various systems throughout the body resulting in hair loss, a compromised immune system, fatigue, nausea, diarrhea, diminished cognitive function (sometimes referred to as “chemo brain"), loss of bladder control, loss of appetite, and a condition called neuropathy, in which one experiences numbness or tingling in the fingers and toes.

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"The side effects of chemotherapy are dependent on the types of drugs the patient is receiving," says Iqbal.

Medical advances have made it easier to manage these side effects. "Nowadays, the great majority of chemotherapies for various cancers are very personalized and targeted and are much easier to tolerate than they were in the previous decades," Ratner says.

What's more, related side effects are often fully reversable. “After the treatment is finished, hair growth and other bodily functions usually resume as before," says Yazan Numan, an oncologist at Northwestern Medical Group in Orland Park, Illinois.

Is chemotherapy for all types of cancer?

Though we often talk about chemotherapy as one treatment, Numan says there are more than 100 types of chemotherapy drugs that can be used to treat different types of cancer.

These generally fit into several categories: antimetabolites, nitrosoureas, corticosteroids, plant alkaloids, anti-tumor antibiotics, biological response modifiers, alkylating agents, and hormonal agents.

"Each drug is effective in a different way at inserting itself and destroying the DNA in cancer cells," Numan says.

Various chemotherapy treatments are determined, in part, by the type of cancer one has, how much it has spread, and by the size of the cancer mass—all factors that also play a part in determining what cancer "stage" with which a person is diagnosed.

Though chemotherapy can be recommended for any type of cancer, the type of adjuvant "preventative" chemotherapy Princess Kate is receiving "is not used universally to treat all cancers," says Beth Karlan, a physician and gynecologic oncologist at UCLA’s Jonsson Comprehensive Cancer Center. "However, it is commonly used for many early breast cancers, colon cancers, and ovarian cancers with curative intent."

The use of adjuvant chemotherapy is also not commonly recommended “for very early-stage cancers when likelihood of residual microscopic disease is very low," says Fong.

Why Princess Kate is likely receiving this treatment

Numan says this suggests that in Princess Kate's case, some microscopic amount of the disease likely remained after her surgery, which still needed to be dealt with through another form of treatment.

Ratner says in her experience with patients, this is common practice. "We worry that if microscopic cancer cells remain, with time they would grow, rapidly divide, metastasize, and take over normal tissues," she explains. "Because of this, we sometimes recommend adjuvant chemotherapy to destroy those cells."

Though we don't know what type of cancer was discovered when she underwent abdominal surgery earlier this year, "Princess Kate received this therapy because her doctors thought this would decrease the likelihood of her cancer coming back," says Dahut.

What her diagnosis means for the rest of us

Princess Kate has access to top medical care and is receiving multiple treatments to both eradicate cancer and prevent it from returning. "Not everyone around the world has access to such care," Numan says.

She is also lucky to have the cancer caught early, which will likely help her avoid the worst outcomes of the disease. "Princess Kate is 42 years old, so most guidelines for cancer screening do not include her age group even though there is a trend of increasingly high incidence of cancer in young patients," says Fong.

Because of this, Numan says her diagnosis can serve as "a wakeup call" for others to get screened.

The American Cancer Society recommends for women to get screened for cervical cancer beginning at age 25 and for breast cancer beginning at age 45. It also recommends colorectal cancer screening for everyone beginning at age 45, for some men to begin prostate cancer screening at age 45, and for people with a family history of cancer or individuals who smoke to discuss with their primary care doctor the possibility of getting screened earlier.

"Nothing is more important in cancer treatments nowadays than early detection," says Ratner. "This is why so much effort and research is being done on effective methods of early cancer detection and prevention, including advocacy and education."