Experts say the online algorithm can accurately predict the risk of reoccurrence of breast cancer and cut post-treatment therapy from 10 to 5 years.

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Hormone therapy after breast cancer treatment can cause numerous side effects. Getty Images

A new algorithm could cut five years off hormone therapy for people who’ve had breast cancer.

The algorithm has been made available for free — and clinicians are already using it.

For those who’ve undergone successful treatment for breast cancer, endocrine therapy — better known as hormone therapy — is often the go-to recommendation to ensure the cancer doesn’t return.

This hormone therapy is generally prescribed for at least 5 years and sometimes up to 10 years. It carries a number of side effects.

However, the new algorithm, called CTS5, could cut hormone therapy in half, from 10 years to 5, for certain patients.

Researchers from The Royal Marsden National Health Service (NHS) Foundation Trust and Queen Mary University of London presented their findings earlier this week.

Experts told Healthline that CTS5 is a simple, effective tool that can help some patients avoid years of unnecessary therapy.

The CTS5 calculator was first published last year and uses a straightforward interface.

“It’s a clinical tool which incorporates age of patient, tumor size, number of nodes involved, and the grade of the tumor,” explained Dr. Lauren S. Cassell, chief of breast surgery at Lenox Hill Hospital in New York.

“As a result, it is able to predict whose risk of recurrence is so low that there is no significant benefit for the patient to continue the endocrine (hormone) treatment after five years,” she told Healthline.

Researchers put the algorithm to the test on “real world” patients to demonstrate its efficacy.

To that end, researchers analyzed data from 2,428 people, finding that CTS5 could accurately predict the probability of a breast cancer relapse after five years.

The participants were assigned a risk level: high, medium, or low.

The group included 700 postmenopausal women, nearly 30 percent of the entire cohort. About 41 percent of them had a risk level so low that hormone therapy can be capped at 5 years rather than 10.

“This will be a help to the clinician and a relief to a significant number of patients,” said Cassell.

“Since we can now identify women who are at low risk of late metastasis, it is obviously crucial to not overtreat these women with hormonal therapy, as they would not benefit from the therapy, but many would still exert the symptoms,” said Dr. Ivana Sestak of the Queen Mary University of London’s Centre for Cancer Prevention and the study’s senior author.

These side effects can include joint pain, weight gain, and exacerbation of menopause symptoms such as hot flashes and osteoporosis.

“These symptoms are the most common reason women stop with hormonal therapy,” Sestak told Healthline. “They can be very stressful for women, as most of them are in their menopause already and the aromatase inhibitors intensify these symptoms even more.”

High-risk patients will generally still need hormone therapy for up to 10 years. But for people at lower risk, the effects of shaving five years off a decade-long treatment can be significant.

The CTS5 calculator is already in use. It’s also free.

Sestak noted that the CTS5 has been available online since August 2018, and it’s been used by more than 18,000 medical oncologists around the world.

“The Royal Marsden has implemented the use of the CTS5 since this time in their weekly multidisciplinary team meetings,” Sestak said. “There have not been any major challenges, as this tool gives clinicians the opportunity to confirm their recommendation for extended endocrine therapy or not.”

Researchers plan to take steps to apply the calculator to other groups of women. Notably, Sestak points out, they’d like to see if CTS5 can be applied to premenopausal women as well.

If it isn’t applicable, a different, tweaked version will need to be developed for that portion of the population.

Another area to investigate is whether CTS5 can be applied to HER2-positive breast cancer, a type of cancer that tests positive for the human epidermal growth factor receptor 2 (HER2) protein, which boosts the growth of cancer cells.

Sestak says researchers used data from a pair of studies that don’t tell the whole picture with regards to HER2-positive breast cancer — and that’s what her colleagues are trying to better understand.

“The data we used from the large ATAC and BIG 1-98 trials for the development of the CTS5 included many women with unknown HER2-positive disease who have a distinctly different disease outcome, and we need to understand better why and when these women develop late metastasis,” she explained.

While medical science is always a work in progress, the CTS5 calculator as it currently stands represents an important new tool in a clinician’s arsenal — one that can help breast cancer patients avoid years of unnecessary hormone therapy.

“It is the goal of those of us treating breast cancer to do less without compromising outcome,” said Cassell.

“The CTS5 is a very simple tool that incorporates information that every clinician has available for their patients,” concluded Sestak. “There is no need for further testing of any markers, and the CTS5 can be applied to any postmenopausal woman who has finished five years of adjuvant hormonal therapy and who did not have a recurrence during those five years.”

“The most attractive part of this tool is that it is freely available, very simple to use, and clinicians can discuss with the patients the results directly with help from graphical explanations from the website.”

For women who’ve had successful standard treatment for breast cancer, 5 to 10 years of hormone therapy is typically prescribed to prevent the cancer from coming back.

But hormone therapy carries a host of side effects, both physical and psychological.

A new calculator, CTS5, can help doctors assess the likelihood of cancer returning. This means that for low-risk patients, hormone therapy can be capped at 5 years rather than 10.

The calculator is free online and is already in use by more than 18,000 oncologists around the world.