Irish healthcare professionals are just as susceptible to old wives’ tales as the general public when it comes to understanding the risk factors for cancer, according to a new study. This revelation came as a surprise to researchers from University College Cork (UCC), whose survey results found that a quarter of health service providers believe wearing a tight bra increases breast cancer risk and 41% are convinced that a blow to the breast does the same. 

While most are aware of the classic risk factors, such as smoking and poor diet, a significant number appear misinformed about several proven cancer risks. Worryingly, three in five healthcare professionals are unaware that obesity greatly increases the risk of cancer, notwithstanding a World Health Organization warning that up to 41% of certain cancer burdens are attributable to overweight and obesity. 

Also, a large majority (78%) is unaware that abdominal fat can cause inflammation and secrete substances implicated in cancer development, while a quarter of health workers do not think the location of fat is important.

“That was the biggest surprise for me,” confides Dr Aoife Ryan, a lecturer in nutritional science at UCC and one of the lead authors of the research. “We didn’t set out to specifically look at healthcare professionals’ awareness of cancer risks but when we broke down the survey data the figures were very similar between what the general public and healthcare professionals believed. Hardly any of them came out as being statistically different, to be honest with you. The results are astonishing; basically, a large portion of the Irish population is misinformed and unaware of the real risk factors for cancer.”

The research, which is the first of its kind in Ireland, was conducted as a final-year thesis by UCC nutritional science undergraduates Lisa Burns and Ursula Kenny, under the guidance of Dr Aoife Ryan and Dr Derek Power, consultant medical oncologist at Cork University Hospital, and in association with Breakthrough Cancer Research and the Irish Cancer Society.

“Lisa and Ursula had to construct the 48-question survey themselves because there was nothing like this done in Ireland before and only one or two similar studies published in the US. That’s where we got the ‘blow to the breast’ idea, it had been asked before in a study many years ago. We were laughing at it, initially, but then we stopped laughing when we saw our results,” says Aoife.

“We had a tremendous response to the survey – 748 people replied. Most of them were women, only 100 men contributed. About 40 or so people declared that they had cancer and 126 (17%) said they were healthcare professionals.”

Common misconceptions

Her research team found that many people overestimate the risks attributable to genetics, environment and stress, and they underestimate age, obesity and sunlight as cancer-contributing factors. Incredibly, almost one in five people believe that they can do nothing personally to prevent cancer if they have a family history of the disease, which is incorrect. 

In addition, 20% of the public and one in 10 healthcare professionals are not aware that cancer risk increases with age – the primary risk factor for the majority of cancers. 

“It’s quite alarming to think that one in five people believes there is nothing they can do about their personal risk. I spoke to some oncologists who were involved in this study and they estimated that less than 5% of cancer is caused by germline mutations where there is nothing you can do; you’re born with the mutation, you will get cancer. So, that leaves more than 95% of cancers you obviously can do something about,” Aoife stresses.

However, the majority (90%) of survey respondents maintain that genetics ‘strongly’ increases risk, with almost three-quarters (73%) of healthcare professionals claiming that more than 10% of cancers are inherited. The figure was similar for the general public (79%).

Stress, as a cancer trigger, was another major misconception, says Aoife: “Ninety-two per cent of people thought stress was a risk factor, in contrast to scientific evidence that shows this is not a risk factor. There are some interesting data from the National Cancer Institute in the US that stress can shorten your lifespan once you have cancer. It’s very hard to study whether stress causes cancer but most people think that it does. 

“We also found that more than half of healthcare professionals (54%) and the public (51%) believe that taking vitamin and mineral supplements can protect you against cancer, and about 20% of both groups thought they should be consumed daily, in contrary to the evidence that suggests we should not be taking them. In fact, high doses of vitamins and minerals can actually increase your risk of certain cancers, especially if you are a smoker,” she cautions.

“This ties in with another myth held by one in five people that nutritional needs cannot be met by diet alone and supplements are absolutely necessary. The majority also believe that detox diets and organic food reduces cancer risk – again there is no evidence to support this. 

“I was surprised to find that 65% of health professionals didn’t know that frozen vegetables and fruit are every bit as good as fresh. The number was similar for the general public. A high number also were not aware that red meat is a risk factor or that salt can increase cancer risk.

“And it seems the red wine message is getting a bit confused: in moderation it may have some cardioprotective effects but about four in 10 people think it can protect against cancer too. Alcohol, any type of alcohol, is associated with an increased risk of a number of cancers. The advice would be to limit alcohol. If consumed at all, limit to two drinks for men and one for women per day,” Aoife advises.

Excess pounds increase risk

A crucial public health message that appears to be missing its mark is that excess pounds do more than increase weight – they increase the risk of cancer, as well as other health problems. In both men and women, being overweight or obese is associated with a higher risk of dying from cancer of the oesophagus, colon and rectum, liver, gallbladder, pancreas or kidney. In men, excess weight also increased the risk of dying from stomach or prostate cancer. Deaths from cancer of the breast, uterus, cervix or ovary were elevated in women with higher body mass index (BMI) – an estimate of an individual’s relative body fat calculated from his or her height and weight. 

Yet, in the UCC survey, only 40% of healthcare professionals and a third of the public are aware of this risk.

“Obesity is a well-known risk factor for many cancers. In some cancers, over half of them are thought to be directly caused by obesity,” remarks Aoife. 

“We also found that a high number of people, including healthcare professionals, did not know about the correlation between cancer and the location of fat in the body. For certain cancers, such as colorectal cancer, it’s not just BMI: it seems to be fat on the waist that increases risk. So visceral fat – deep-lying fat in the abdomen – is very metabolically active, secreting a whole host of substances that are implicated in cancer growth,” she explains.

“We published a number of research papers, when I worked in St James’s Hospital in Dublin with Prof John Reynolds, looking at obesity and cancer. We found that being overweight increased the risk of oesophageal cancer 11-fold in Irish people. We also found that a person with cancer who is obese is worse off – in a number of cancers we found that obese patients have on average 2cm bigger tumours and have more lymph nodes and vascular invasion than thinner people.

“What struck those of us involved in the UCC research is that this is a very well educated population, in fact it may even be biased in that they are too well educated: 52% of them had a college degree and one in five had a postgraduate degree, even though we deliberately did not send out the survey through the university. We tried to get a sample of the general public but we obviously got an educated sample, and even still there was a surprising amount of old wives’ tales and misinformation about cancer risks.”

Dr Derek Power, co-author of the study, adds: “We hope that by sharing these common misunderstandings and informing the public about proven cancer risks and preventable measures, we can help people to make lifestyle choices that will reduce their risk of developing the disease. This will ultimately help to decrease the growing statistics of those diagnosed with cancer in Ireland.”

With up to 41% of certain cancer burdens attributable to overweight and obesity, the study authors maintain that it is vital to raise awareness of obesity and physical inactivity as risk factors. However, it seems that as a nation we are in denial about our expanding waistlines. Despite the fact that two-thirds of the Irish population are either overweight or obese, recent research by safefood – the all-island food safety promotion agency – found that only 40% of people acknowledge that they have a weight problem. 

Changing the future

In June of last year, 10 health advisory groups made comprehensive submissions to the Seanad Public Consultation Committee on how lifestyle changes can help prevent cancer. Dr Kate Allen of the World Cancer Research Fund (WCRF) informed the meeting that Ireland was number two in the world for cancer rates, with an age-standardised rate of 317 per 100,000. Only Denmark has a higher rate.

A recent report, the WCRF UK, projects a rise in new cancer cases in Ireland by up to 72% by 2030, with lifestyle factors a significant component in that increase.

“I do not know why Ireland ranks so high, but I imagine the reason has to do with the consumption of food,” Dr Allen remarked. However, she stressed that while lifestyle factors are fuelling the epidemic this projection is not set in stone: “Cancer rates are neither fixed nor inevitable... we can take actions to change people’s behaviour with regard to food and nutrition and physical activity and to make an impact on the cancer rates.”

She reiterated a number of the key recommendations issued by a large panel of international experts, convened by the WCRF to analyse more than 7,000 studies on food, nutrition, physical activity and cancer. 

“The first three recommendations are connected with weight and activity. It is recommended that one be as lean as possible within the normal weight range, be physically active as part of everyday life, limit consumption of energy-dense foods and avoid sugary drinks. 

“The next five recommendations are to do with plant and animal foods. It is recommended that one eat mostly foods of plant origin, limit the intake of red meat, alcoholic drinks and the consumption of salt, and aim to meet nutritional needs through diet alone,” she said.

Also addressing the Seanad committee, Dr Triona McCarthy, a consultant in public health medicine who works with the National Cancer Control Programme, focused on sending a positive public health message: “It is not inevitable that one will be diagnosed with cancer. Cancer is not something that everyone will get. The message I want this group to take away is how can we influence our society and environment to make living a healthy lifestyle the easier choice for people to make.”