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What is preventative chemotherapy and how does it work?

Read Time: 4 minutes

IV bag with blurry image of doctors behind it

In March 2024, Catherine, the Princess of Wales, announced her cancer diagnosis. The 42-year-old did not reveal the type of cancer she was facing but shared that she had undergone major abdominal surgery earlier in the year.

“The surgery was successful. However, tests after the operation found cancer had been present,” the princess said in a . “My medical team therefore advised I should undergo a course of preventative chemotherapy, and I’m now in the early stages of that treatment.”

News of the princess’s diagnosis resonated worldwide—and so did her use of the phrase “preventative chemotherapy.” Ann Wilson, lead singer of the rock band Heart, used the same term a few months later when about her own cancer diagnosis. A showed a spike in searches for “preventative chemotherapy” following the royal announcement, with almost no searches beforehand.

What is preventative chemotherapy?

“The medical term used for preventative chemotherapy is ,” says Heloisa Soares, MD, PhD, medical oncologist specializing in gastrointestinal and neuroendocrine cancers and associate professor at Huntsman Cancer Institute at the . “It is the use of chemotherapy after the primary curative-intent treatment has been done to remove the cancer, such as surgery, to decrease the odds of the cancer recurring. Adjuvant chemotherapy is used when the risk of the cancer recurrence is considered somewhat high in order to decrease the odds of cancer returning.”

Dr. Soares suggests the royal family may have chosen the word “preventative” to make the idea more accessible for the public. The term adjuvant, which stems from the Latin “to help,” isn’t commonly known.

“The medical term for preventative chemotherapy is adjuvant chemotherapy.”

However, preventative chemotherapy should not be confused with cancer prevention—medical and lifestyle decisions aimed at minimizing cancer risk. Adjuvant chemotherapy does not prevent cancer from occurring—but can reduce the risk of recurrence.

Chemotherapy is just one form of adjuvant treatment. Depending on the type of cancer, doctors may also recommend other therapies, such as immunotherapy or radiation after surgery.

A patient's perspective

Cristina Grossi was born and raised in Holladay, UT. The administrative assistant lives in the same home she grew up in, alongside her mother and 22-year-old daughter. When she turned 50 in 2019, she marked her milestone birthday with an important health appointment.

“I thought, ‘oh my gosh, I have to schedule my colonoscopy. I had taken my mom in for hers, she was fine. You just do your duty. I thought nothing of it,” says Cristina. “Afterward, my doctor said he was very sorry, but that they had found cancer. I was just dumbfounded. It was supposed to be routine.”

This was Cristina’s third cancer diagnosis. More than a decade earlier, she had been treated for two unrelated sarcomas in her right arm.

“Chemotherapy was like a precaution. If one of those cells was still active, it could bloom into a whole other case.”

—Cristina Grossi

Her colon cancer had been caught early, and she underwent surgery to take out the tumor. Surgeons at Huntsman Cancer Institute removed about a foot of her intestines. But her oncologist, Dr. Soares, recommended adjuvant chemotherapy to complement her surgical treatment.

“Dr. Soares said they couldn’t know if they got it all. Chemotherapy was like a precaution,” says Cristina. “If one of those cells was still active, it could bloom into a whole other case.”

When is adjuvant chemotherapy recommended?

Dr. Soares recommends adjuvant treatments in specific cases, but the decision ultimately rests with the patient. Success rates vary depending on the patient’s particular situation and cancer type. 

“The way that I explain this is that if you don’t do the treatment, your chance of the tumor coming back is X, let’s say 30%. If you do the adjuvant treatment, the change will decrease to Y, let’s say 10%. And then the patient decides if this extra percent of improvement is worth it to them,” says Soares. “You would be surprised by how the threshold of that decision changes patient by patient.”

“The patient decides if this extra percent of improvement is worth it to them.”

—Heloisa Soares, MD, PhD

Soares adds that this type of cancer care is constantly evolving.

“We’ve been doing adjuvant treatments for a long time, and I think we’re getting better and better at improving how we do these things,” says Soares.

A Welcome Call

Cristina learned this firsthand. She decided to move forward with adjuvant chemotherapy and began her six-month course as the COVID-19 epidemic shut down the world. Like many patients at that time, Cristina underwent chemotherapy alone. She says it was a difficult period of her life, dealing with both solitude and the side effects.

Halfway through Cristina’s treatment, however, Dr. Soares called with unexpected news. A recent study showed that a three-month regimen of chemotherapy was just as effective as six months for her specific type of cancer. Her treatment period was cut in half.

“I would go through the chemotherapy again, because I realize that this is the science that works...It’s tough, but it’s worth it.”

“And I said, ‘Oh my gosh, I have a chemotherapy appointment tomorrow morning. What should I do?’” says Cristina. “And Dr. Soares said, ‘sleep in.’ I was overjoyed. I couldn’t have been any luckier.”

Four years later, Cristina remains cancer-free and grateful for the adjuvant—or preventative—treatment she received after surgery.

“I would go through the chemotherapy again, because I realize that this is the science that works,” says Cristina. “If you want a chance to live and feel normal again, you have to go through the really hard part. It’s tough, but it’s worth it.”

Cancer touches all of us.