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A new trial seeks to assess whether proton beam therapy for breast cancer reduces heart risks. Image credit: RFBSIP/Adobe Stock.
  • Breast cancer affects people worldwide, and treatment typically involves a combination of therapies.
  • Radiation is a common component of breast cancer treatment, but it can increase the risk of heart problems in some people.
  • A​ clinical trial has just launched in the United Kingdom that plans to test the effectiveness of proton beam therapy to treat breast cancer in people at higher risk for heart problems after radiotherapy.

Cancer treatment has progressed over the years, with people having access to more targeted therapies. Breast cancer is a highly prevalent form of cancer that experts are still trying to find the best way to treat.

A clinical trial called PARABLE has just launched in the United Kingdom, with the aim of looking at a specialized type of treatment that may be helpful for individuals at high risk of heart disease after traditional radiotherapy.

Researchers plan to compare the use of proton beam therapy and current radiotherapy in the treatment of breast cancer.

According to the World Health Organization (WHO), breast cancer is the world’s most prevalent type of cancer. While breast cancer mainly impacts women, it also affects some men.

In 2020 alone, 685,000 deaths were caused by breast cancer.

Radiation oncologist D​r. Hesham Gayar, the medical director at the McLaren Proton Therapy center, part of the Karmanos Cancer Network, who is not involved in the current trial, explained to Medical News Today:

“Breast cancer is very serious. It affects about 260,000 women every year in the United States alone, and it kills about 43,000 women every year. Incidence statistics show that 13% of all women will get breast cancer. That is one out of eight women in the U.S.”

Treatment for breast cancer often involves a combination of several approaches to help ensure effectiveness. “Breast cancer is treated with surgery, chemotherapy and radiation. Each of those modalities has its side effects and risk of complications,” Dr. Gayar explained.

Radiation is part of treatment for breast cancer that comes with certain risks. In some people, it can increase their risk of heart problems.

The researchers in this particular trial want to test the effectiveness of using proton beam therapy to treat breast cancer in people more likely to develop heart problems related to radiation therapy.

Proton beam therapy still provides radiation, but the method is more precise than standard radiation, thus minimizing damage to healthy tissues.

This form of therapy is already used in the treatment of some tumors, including brain, pancreatic, liver, and lung tumors. Existing research suggests that it may also be safer than traditional radiotherapy in the treatment of breast cancer.

The current study focuses on a particular subset of individuals, namely those who are at risk of experiencing heart problems following radiotherapy for breast cancer.

Chief investigator of the PARABLE trial Prof. Charlotte Coles, professor of breast cancer clinical oncology at the University of Cambridge, and consultant oncologist at Addenbrooke’s Hospital, explained that standard x-ray radiotherapy is effective for the majority of patients with breast cancer in the U.K.

However, she went on to explain to MNT:

“[T]here are a few people – around 500 per year – who have a slightly higher risk of heart problems from radiotherapy in the years and decades following treatment. We estimate around a 2% or more lifetime risk – typically this is because their breast tissue or lymph nodes that require treatment are located close to their heart or they already have heart problems.”

“We want to investigate a newer treatment – proton beam therapy – that uses charged particles instead of x-rays – that can target hard-to-treat tumours in critical regions in the body such as near the heart,” said Prof. Coles.

Researchers from the Institute of Cancer Research ICR in London, The Royal Marsden NHS Foundation Trust, and The University of Cambridge are all working together to make this trial possible.

The trial is a phase III, multicenter, randomized trial. The trial’s researchers are aiming to recruit 192 participants. All participants will receive 3 weeks’ worth of treatment, either proton beam therapy or tailored radiotherapy.

Researchers then plan to look at the radiation amounts the heart receives in treatment to predict future potential heart problems.

The trial will test the effectiveness of this particular type of treatment. However, it remains unclear how common this treatment could become.

One area of concern is the cost of using proton beam therapy, which would influence its ability to become a mainstream treatment option.

Radiation oncologist Dr. Christian Okoye, from The Weinberg Center at Mercy, who is not involved with the trial, noted to MNT:

“In the U.S., the issues with protons surround cost — it is more expensive to deliver than standard photon-based treatments — and access [as] there are far fewer centers that have protons than traditional photon-based treatments. For it to make sense, the treatment has to be superior to the standard treatment to justify the cost/ expenses associated.”

This trial could mean showing that proton beam therapy is worth its cost.

Dr. Gayar has participated in the design of a similar study in the U.S. that is now complete, but whose results are still pending.

He noted that the U.S. study is “expected to show [a] significant advantage to proton therapy for protecting the heart for left-sided breast cancer patients and for patients who require radiation treatment of the regional lymphatics in addition to the breast or chest wall after a mastectomy.”

Should such trials demonstrate a superior advantage, it could lead to proton beam therapy becoming more widely available as a treatment option for those more at risk for heart problems.

Professor Coles laid out the potential timeline for the trial:

“We aim to finish recruitment in 2025 and have the result of the trial in 2027. If we find that proton beam therapy is needed, we hope that the trial will drive practice change in the NHS [U.K.’s National Health Service] to safely roll out proton beam therapy for every patient with breast cancer in the U.K., wherever they live, who needs it because they’re at risk of heart problems.”