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NCRP, Keeping you informed: Are modern life aspects a result in increasing cancer risks in children?


Many assume that certain aspects of modern life are killing children, which rather ignores the fact that survival rates from cancer in children and young people have been progressively improving for several decades. As a result of the press coverage linking lifestyle with cancer, some parents have been left feeling they are to blame for their child’s illness. This is unproductive, particularly given that the available data does not back up such claims, and hits out at parents inappropriately at what is already a distressing and emotional time for them.


We present some of the facts from the scientific literature that lie behind these rather sensational claims.

  • Cancer occurrence in children, teenagers and young adults has risen over the last three decades, but still mainly remains a rare disease.

  • Improvements in diagnosis and changes in how cancer cases are recorded contribute to the apparent increases in the incidence of some cancers, including bowel and ovarian cancer.

  • Most of the increase is seen in cancers in the teenage and young adult age range, or in very rare cancers where the annual number of cases are very small

  • Some of this increase is real and is a cause for concern.

  • In most cases, the link between environmental factors and cancer in children, teenagers and young adults is preliminary or generally very weak.

  • In the case of power lines, previous suggestion of a link with the development of childhood cancer has not been found to be present in larger and more recent studies.

  • Studies that report links between environmental exposures and cancers try to rule out other factors, but this is difficult and so the studies can at best describe ‘associations’, which is very different to suggesting that these exposures actually cause cancer.

Cancer incidence in children aged 0-14 years has risen over the last two decades from 141.7/million in 1993-5 to 153 per million in 2011-131. This represents an 8.1% increase in the number of cancers diagnosed in children per year, but childhood cancer remains very rare (about 1 in 6500 children per year). In young people aged 15-24 the incidence has risen from 225 per million in 1993-95 to 267 per million in 2010-122 representing a 19% increase. Again, cancer in young people is rare (about 1 in 3750 15 to 24-year-olds per year).


Improvements in cancer diagnosis and changes in how cancer cases are recorded definitely contribute to the apparent increases in the incidence of some cancers, such as bowel and ovarian cancer. However, some of this increase is real and is a cause for concern.

  • For instance, melanoma incidence in young people has increased significantly in young people over the last two decades, likely related to patterns of exposure to sun and sunbeds.

The evidence in support of the risk factors for these cancers is strong and they are both either easily avoidable (by avoiding sunbed use, sunburn, unprotected sex) or there are interventions that young people can use to reduce their risk (HPV vaccine). Neither of these well-known and avoidable risk factors, nor the uncertainty around real versus apparent increases in cancer incidence was made clear in the recent press coverage.

Some of the influences of ‘modern life’ reported have supporting scientific evidence, and in the case of the association between children who attend daycare and cancer risk, there is actually a reduction in the risk of developing leukaemia. This protective association has been described extensively in the scientific literature. In most cases the links between environment and cancer is preliminary or weak, and in the case of power lines, previous evidence of a link is no longer present.


Importantly, epidemiological studies that report links between environmental exposures and cancers try to rule out other factors such as social deprivation that might make associations appear where there are none. Even so, epidemiological studies cannot rule out all factors and can at best describe associations. That is not the same as saying that the environmental factor causes the cancer, and there are many examples in the scientific literature where initial associations have been subsequently ruled out or shown to be coincidental in larger studies. The evolution of the evidence for and against a link between childhood cancer and electric power lines is an important example.


Ultimately, there are some environmental exposures that clearly ‘cause’ cancer such as excessive sun exposure and HPV infection and, in an older population, smoking, obesity and diet. There are also some clear associations between the environment and cancer that have been shown across multiple studies, such as the association between exposure to daycare and relative protection from childhood acute leukemia. There is a much larger group of environmental exposures with less robust evidence that might possibly be associated with increased risk of cancer, and may in some cases even cause cancer, but cannot be regarded as clear risk factors without further study. Most of the factors described in the recent press coverage fall into this last group and while scientifically interesting, should be viewed as preliminary.


The identification of possible environmental factors linked to the development of pediatric cancer does not translate directly into actions which parents can reasonably take to substantially alter the possible risk to their children, based on current evidence. At NCRP, we would therefore urge the media and the experts parents consult to exercise extreme caution in reporting such associations, and to avoid sensational headlines, mindful of the profound impact they may have on vulnerable families.


 

Resources


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7 Maternal and childhood consumption of coffee, tea and cola beverages in association with childhood leukemia: a meta-analysis. Thomopoulos TP, Ntouvelis E, Diamantaras AA, Tzanoudaki M, Baka M, Hatzipantelis E, Kourti M, Polychronopoulou S, Sidi V, Stiakaki E, Moschovi M, Kantzanou M, Petridou ET. Cancer Epidemiol. 2015 Dec;39(6):1047-59.

8 Childhood acute lymphoblastic leukemia and indicators of early immune stimulation: a Childhood Leukemia International Consortium study. Rudant J, Lightfoot T, Urayama KY, Petridou E, Dockerty JD, Magnani C, Milne E, Spector LG, Ashton LJ, Dessypris N, Kang AY, Miller M, Rondelli R, Simpson J, Stiakaki E, Orsi L, Roman E, Metayer C, Infante-Rivard C, Clavel J. Am J Epidemiol. 2015 Apr 15;181(8):549-62.



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