Three breast cancer patients are part of a world-first trial that is the first of its kind on the National Health Service.
Patients with difficult-to-treat growths in critical areas are more likely to benefit from the hi-tech treatment. Patients with tumors in and around their brain or spine have been treated by the National Health Service.
The first of its kind in the world, the trial will compare proton beam therapy with standard radiotherapy for patients who are deemed to be at higher risk of long term heart problems after treatment.
Prof David Sebag-Montefiore was the former chair of the National Cancer Research Institute's clinical and radiotherapy research working group.
Kim Jones, a school caterer from Ely, is one of three patients who have undergone the trial on the National Health Service. She was diagnosed with breast cancer in February after she noticed some pain in her breast.
The cancer patient was referred to the Addenbrooke's hospital in Cambridge, where she had her mastectomies and other procedures. She successfully completed her therapy at the Christie hospital in Manchester last month.
Jones said that he felt lucky to have the chance to receive the treatment. The Parable trial may benefit patients with a high risk of long-term heart problems. I had an issue with my heart and the trial seemed like a good idea.
The treatment, in which high-energy charged particles from the centre of atoms, called protons, were used to target her cancer, was described by Jones as being very relaxing.
The trial will determine if protons beam therapy can help deliver adequate doses of radiotherapy to the breast while also reducing radiation around the heart.
There are 192 patients that will be part of the trial. The Christie or University College London hospitals will be used for the treatment of patients who are far away.
The trial is being led by medics, scientists and researchers at the University of Cambridge.
According to Prof Judith Bliss, director of the Cancer Research UK-funded clinical trials and statistics unit, radiotherapy is a very effective part of treatment for breast cancer that helps to lower the risk of cancer returning and has been shown to improve survival.
It can be difficult to effectively deliver standard radiotherapy when the patient's breast tissue is close to their heart or they already have a heart problem.
Breast cancer patients in the UK receive about 30,000 radiotherapy treatments every year.
The benefits of radiotherapy outweigh the drawbacks for most patients. There is a small chance that it will lead to heart problems later in life, but less than 1% of all those treated.
For a small group of breast cancer patients, the risk of heart problems is higher than 1%. They are more likely to have heart problems later in life if their breast tissue is located close to the heart.
It can still be a serious issue if a small group of people are affected by a higher risk of heart problems later in life.
The trial's chief investigator, a consultant oncologist at Addenbrooke's, said that standard breast radiotherapy is effective for most people with very few side-effects.
Patients with a 2% or higher potential lifetime risk of heart problems from radiation will be invited to participate. Out of every 30,000 people who get breast cancer treatment, 500 fall into this category.
In other countries, proton beam therapy has been used to treat breast cancer, but the trials have been small and there have been no trials that compared the two.
The trial is being funded by the National Institute for Health and Care Research.