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Proton therapy for prostate cancer: does the evidence support the hype?

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High energy proton beam therapy, an advanced form of radiotherapy, made its debut in the UK in 2018. Both the NHS and private clinics began offering this treatment in the same year, but they treated very different patient groups. While the NHS used the therapy to treat childhood cancer, private clinics began treating men with prostate


The situation is similar in other countries. Prostate patients are the most common referral for proton beam therapy in the US and internationally make up the majority treated at many proton centres.


But who sees the greatest benefit from proton beam therapy? And do these benefits justify the substantial cost of treatment (often tens of thousands of pounds)? While there is strong evidence for the benefits of proton therapy in children, it is much less clear in prostate and other adult cancers.


This apparent disconnect between evidence and practice underpins fundamental disagreements about the standard of evidence needed for new treatments and the role of patient choice in healthcare.


Why protons?


Proton therapy is an alternative form of radiotherapy, which is conventionally delivered using X-rays. Both approaches aim beams of radiation at the tumour, killing cancerous cells when they interact with and damage the patient’s DNA. But radiation can also damage healthy tissues and organs that surround the tumour, which can cause side effects.


Modern X-ray radiotherapy minimises these side effects using clever delivery methods. The tumour is treated from many different directions, meaning it can be given a greater dose of radiation while reducing the dose to healthy tissues, and hence the damage. But X-ray radiotherapy still delivers a significant radiation dose to healthy tissues that lie in front of and behind the tumour.


Unlike photons (used in X-ray radiotherapy) which travel right through the body, protons only travel a certain distance through the body before stopping. By carefully tuning this range, it is possible for proton therapy to deliver almost no dose beyond the tumour. This greatly reduces the total dose to healthy tissues.


It is argued that this advantage makes proton therapy a better approach than conventional radiotherapy. And this is true for some cancers. For example, reducing the total dose received by children significantly reduces risks of delays in their development and additional cancers later in life. Protons can also make it easier to deliver precise treatments to tumours close to sensitive organs, such as the spinal cord or optic nerve.


Protons in prostate cancer


In prostate (and many other adult cancers) the benefits are less clear. A big advantage of protons is the reduction in the total dose delivered to the patient. However, the main side effects associated with this are much less significant in adults: delays in development are not a factor, and the risk of additional cancers are much lower as they typically take decades to develop.


Instead, the main side effects are seen in organs close to the prostate that also receive a high dose, such as the bladder and rectum. A high dose must be delivered to a region that includes the prostate and some additional healthy tissues, to make sure the disease is treated fully. The extra margin allows for the variation that occurs during treatment, such as differences in the way the patient lies down, to make sure the cancer gets a full dose each day. As these patient variations are independent of the radiation type, protons and X-rays typically deliver similar high doses to these healthy tissues.


Despite this, proton therapy has been widely adopted because it is argued the physical benefits are clear, even if small, and will become apparent with time as more people reach the five and ten-year survival mark. But the results of studies investigating the effects of proton therapy on are mixed. While protons have been shown to an effective treatment for prostate cancer, no consistent advantage has been seen for either long-term survival or quality of life.


One challenge in measuring the benefit of proton therapy for is that conventional radiotherapy is already highly effective. In early stage (stages one to three), nine out of ten men treated with X-rays are expected to remain cancer free after five years. They also have relatively low rates of long-term side effects compared with many other cancers. As a result, there is a limited scope for proton therapy to improve outcomes, precisely because the outcomes are already so good. As technology develops this will further reduce side effects and improve rates of remission in conventional radiotherapy, and mean it is increasingly hard to show a benefit from proton beam therapy.


As a result, the NHS and the American Society for Radiation Oncology (ASTRO) do not recommend proton therapy for prostate cancer except as part of a clinical trial. Several of these large international trials are underway, but it will be about a decade before we have conclusive results. Even then, it is expected that protons will represent, at best, an evolution rather than a revolution in prostate

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This has not prevented a demand for prostate proton therapy driving a dramatic expansion in the number of proton therapy centres internationally. In part this is because prostate cancer is one of the most common types of cancer. Treatment for common cancers may actually serve to support the availability of proton therapy for other, rarer cancers. But, it is crucial the benefits for every individual are properly considered.


It is difficult for dry position statements from organisations like the NHS and ASTRO to compete with the dramatic promises proton therapy clinics make. But a balanced discussion of the benefits and costs of all types of radiotherapy is essential to ensure patients have all the evidence to hand before they part with their cash.



Stephen McMahon, Queen’s University Research Fellow, Queen’s University Belfast


This article is republished from The Conversation under a Creative Commons license. Read the original article.


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Sick hospital workers often expose patients to contagious illness

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Hospital workers often come to work with contagious respiratory illnesses, against the recommendations of public regulators, a Canadian study suggests.


Nearly all of the 2,093 care workers in the study who had such symptoms came to work at some point while sick.


For the study, published in the Journal of Infection Control & Hospital Epidemiology, nurses, doctors, and support staff at nine across Canada filled in online illness diaries during four flu seasons, recording symptoms such as a runny or stuffy nose, fever, cough or scratchy throat.


Of the 1,036 participants who had contagious respiratory illnesses during the study period, 52% reported working on every scheduled day of work and 94.6% reported working at least one day of their illness.


The most common reason given for working while sick was that the illness seemed mild and manageable. Compared to other care workers, physicians were more likely to work while sick and nurses were less likely.


But nurses who thought their managers expected them to show up unless they were too sick were more likely to feel obligated to work.


For most people, in fact, feeling obligated was a driving factor behind their decision to come to work sick, as was their perceptions of what managers expected from them. Younger workers, and workers without paid sick leave, were more likely to say they could not afford to stay home.


“It is only by knowing these reasons that managers and employers can take steps to mitigate the risk of infection to other people,” said Brenda Coleman, senior study author of the study from the Dalla Lana School of Public Health, University of Toronto, in email to Reuters Health. Eleven percent of the hospital workers said they had come to work even while feeling miserable because they had “things to do.” Physicians were under-represented in the study, and self-reporting of the illnesses may also confound the results, the authors acknowledge in their report.


The US Centers for Disease Control and Prevention advises workers to take seven days off or consider temporary reassignment if they have a fever and respiratory symptoms.


The research team suggests that changing sick leave policies and cultural norms could help reduce the risk of disease transmission from sick health care workers to patients.


Also needed, the researchers say, is an understanding of how to balance the costs and risks of absenteeism by sick workers against the costs and risks of illness transmission associated with working while ill.


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First two cases of Ebola confirmed in Congo’s South Kivu: Officials

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A woman and her child were the first two cases confirmed with in Congo’s South Kivu region this week, opening a new front in the fight against the outbreak.


Health officials said on Friday that the latest cases were more than 700 km (430 miles) south of where the outbreak was first detected.


has killed at least 1,900 people in Democratic Republic of Congo over the past year. This is the second biggest toll ever and militia violence combined with local resistance have made the outbreak harder to contain.


The 24-year-old woman had been identified as a high-risk contact of another case in Beni, more than 700 km north, last month, according to a government statement issued on Friday.


She travelled by bus, boat and road with her two children to Mwenga, in South Kivu, where she died on Tuesday night, according to a slide from a presentation by health officials.


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Research shows how nordic walking may benefit breast cancer patients

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Nordic walking, an aerobic activity performed with walking poles similar to ski poles, may benefit patients with breast cancer, according to a review of existing research.


The low-impact exercise improved swelling, physical fitness, disability and quality of life, the study authors conclude in the European Journal of Cancer Care.


“The main strategy in rehabilitation for women with is a change of habits, where physical exercise is a fundamental tool,” said study co-author Jorge Torres of the Faculty of Educational Sciences and Sports at the University of Vigo in Pontevedra, Spain.


“It’s not easy to turn a sedentary person into an amateur athlete, so sports such as Nordic walking are accepted more easily,” Torres told Reuters Health by email, particularly since the activity doesn’t require expensive equipment, can be done in a group with others, and is easy to learn.


Introduced in the 1980s as a summer training exercise that was similar to cross-country, or Nordic, skiing, Nordic walking became more widespread in the 2000s. It’s now part of some exercise-based rehabilitation programs, especially in Northern Europe where it is more common, Torres noted.


He also owns a personal training company, Vigo Entrena, that creates physical activity programs for people with specific needs, including injuries, obesity, pregnancy, postpartum and women with breast cancer, and he specializes in Nordic walking training.


To see if this form of exercise helps women treated for to reduce side effects like arm swelling, and offers other benefits of exercise, Torres and his colleagues analyzed nine studies. Four studies were randomized controlled trials comparing Nordic walking to other activities; the other studies focused on specific effects of Nordic walking.


Periods of exercise in the studies ranged from 30 to 80 minutes and were performed on one to five days a week for up to 12 weeks.


In eight of the nine studies, Nordic walking had a positive effect on a number of symptoms, including lymphedema, fitness, upper-body strength, disability and perceptions of pain and swelling.


A handful of studies also showed improvements in depression, self-efficacy for managing pain and improvements in physical activity levels. They didn’t find any adverse effects, and the study participants seemed to stick with the programs.


The biomechanical gesture of Nordic walking, compared to just walking, seemed to counteract some of the side effects that can come from cancer treatment, such as shoulder-arm mobility and postural problems, the study team writes.


“(Many) health professionals and therapists do not realize that there are contraindicated exercises during breast cancer rehabilitation and that alternatives such as Nordic walking can be very effective,” Torres said.


“Nordic walking is a structured form of physical activity which nowadays has been shown to be ‘more complete’ than basic walking,” said Marco Bergamin of the University of Padova in Italy, who wasn’t involved in the research review.


“Another important point that is less stressed by these authors: quality of life,” Bergamin said in an email. “Nordic walking gives huge benefits because breast cancer patients are survivors, and from a socio-psychological point of view, that really impacts their life.”


Future studies should also investigate the intensity, frequency, duration, and length of exercise needed to help breast cancer patients, said Lucia Cugusi of the University of Cagliari in Italy, who also wasn’t involved in the review.


“What is most evident is the growing interest of the scientific community in tracking the needs, interests and preferences of patients,” Cugusi said by email.


“Offering them novel forms of physical activity that are both effective and engaging has become one of the new and stimulating research fields in cancer therapy and management.”


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