A risk factor is anything that increases an individual’s chance of developing a disease , but identifying and validating risk factors can take time. Here, we look at the past to reveal some surprising perceptions about risk factors that are now widely known to be associated with cancer. We also consider how our awareness of risk factors has moved on, so much so that we may have gone too far in the opposite direction, and look at why the medical and scientific communications industry has a vital role in addressing this imbalance.
Tobacco use is associated with approximately 20% of global cancer deaths and its risks are now well known . However, historically, tobacco was known as a ‘holy herb’ or ‘God’s remedy’ and was thought to have many therapeutic uses – in the late 18th century, tobacco smoke enemas became widely used all over Europe for various diseases, and tobacco was even used as an antiseptic as late as the early 20th century (Figure 1) . Around the 1950s, research began to prove a link between smoking and lung cancer, and smoking in Britain slowly began to decline .
Radiation is another well-known risk factor because exposure to certain wavelengths of radiation can cause damage to DNA and cause cancer . However, in the 20th century, high volumes of products such as Radithor (distilled water containing radium-226 and radium-228) were sold due to claims that they could cure many ailments. This industry collapsed when wealthy industrialist Eben Byers lost the majority of his jaw following consumption of large quantities of Radithor and died from radium poisoning soon afterwards – the case highlighted to the general public the dangers of internal radium [5,6].
Another form of radiation is ultraviolet (UV) radiation, the main source of which is the sun . Although UV exposure has been linked with skin cancer since the late 19th century, the idea of a ‘healthy tan’ came about in the 20th century when it was decided that sunlight could be used as a treatment for many different diseases (Figure 1). Between the 1960s and 1990s, incidence of melanoma increased by 244% in men and 167% in women and, even with an increased awareness of the risks of UV exposure and better protection available, these figures are continuing to rise .
Arsenic, in addition to being a potent toxin, is a known risk factor for lung, bladder and skin cancers . However, in the 19th century, arsenic was widely used for different applications (Figure 1). This was fuelled by the perceived benefits gained by people in the mountainous region of Styria in Austria, who ate arsenical compounds – women would use them to help their complexion and put on weight to appear more desirable to men, and men would eat them in order to improve their breathing on mountain climbs . The safety of arsenic was put into doubt following cases of poisoning from use of the green pigment in everyday materials and although it was still used in pesticides in the late 1800s and early 1900s, these were gradually phased out due to health concerns .
Figure 1. Some surprising historical uses of substances now known to cause cancer [3,4,8,9,11,12].
It is clear that we were once oblivious to our exposure to risk factors for cancer, but the public perception of cancer risk now appears to have gone the other way. The media now seem to be, slowly but surely, throwing every substance into the spotlight as a potential risk factor – baby rice, lipstick, Nutella, processed meats and, most recently, browned toast, potatoes and chips are just some of the items that have featured in the headlines as cancer-causing agents
For a claim that a substance is a risk factor for a disease to be valid, it should be supported by reliable data demonstrating a significant association between exposure to this substance and the development of a disease. While this is not the place to explore the validity of each of the aforementioned claims, suffice to say that there is scepticism about how much we should act on such reports from the media [18,19].
The changes in our awareness of cancer risk over time highlight the importance of education and scientific accuracy. The public need to be made aware of the things that may be harmful to their health, and the recommendations they receive should always be based on clear, substantiated data. The healthcare professionals that provide guidance to the public are expected to keep up to date about new developments and changes in recommendations so that they can always provide appropriate advice.
For this to be possible, key messages must be clearly defined, claims must be rigorously reviewed and fact-checked to ensure that they are supported by credible data, and appropriate channels to communicate this information must be defined. The medical and scientific communications industry therefore has a paramount role in shaping public knowledge and awareness of disease.
These actions, we hope, will ensure that future generations do not look back and find our perception of cancer risk quite so ‘surprising’.
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13. BBC News. Browned toast and potatoes are ‘potential cancer risk’, say food scientists. Available at: http://www.bbc.co.uk/news/health-38680622. Accessed February 2017.
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17. Mail Online. Is your lipstick giving you cancer? Available at: http://www.dailymail.co.uk/health/article-499967/Is-lipstick-giving-cancer.html. Accessed February 2017.
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