Big Family, Small Risk of Cancer
Did you grow up in a large family with several siblings? You may remember a lot of chaos, jockeying for your parents’ attention, and complaints about wearing hand-me-downs, but there was probably a lot of love and companionship as well. While that somewhat crowded upbringing might have taught you some questionable life skills—such as eating quickly enough to take a second helping at dinner before it disappeared—you might also end up with a major, unexpected health benefit according to new research.
The study, which was conducted in a joint effort by researchers at the Institute of Evolutionary Medicine at the University of Zurich in Switzerland and the University of Adelaide in Australia, found that people brought up in countries in which most family sizes are larger may have a lower risk of developing cancer.1 These results are based on an analysis of data collected by the United Nations that includes average family size and prevalence of diseases.
The researchers evaluated information that had been gathered by several different U.N. agencies on 178 nations around the world. The information included each country’s cancer rates, incidence of various types of cancer, average household size, fertility rates, life expectancy, socioeconomic factors, and biological state index, which uses probability to assess the likelihood of a person having children. Therefore, average family sizes were determined by calculating the number of children a woman in a particular region would typically have throughout her childbearing years.
By creating a graph to chart the size of families against the cancer rate information, it became clear that areas where larger numbers of children were born had fewer diagnoses of cancer. Even when the investigators controlled for various influencing factors such as age, income levels, and urban development, the findings held up. Not only were overall cancer rates lower where large families are common, but certain specific forms of cancer were especially reduced. These include cancer of the bladder, brain, breast, cervix, colon and rectum, lung, ovaries, and stomach, as well as melanoma.
As far as women go, this falls in line with earlier research outcomes, such as a 2018 study at the University of Oxford in the United Kingdom, which showed that a woman’s chance of developing ovarian cancer drops with each pregnancy.2 It is, however, counter to a 2011 study at the Fred Hutchinson Cancer Research Center in Seattle, Washington, in which the risk of certain forms of breast cancer was shown to be higher for women who had several children.3 That said, the current research found that men derived an even greater benefit from being part of a large family, so any difference can’t be attributed to only pregnancy hormones and childbirth.
So, what is it that could be the positive influence of having a bigger family? Chances are, at least some of the impact is due to the mental advantages of having a larger support network and feeling loved. Plenty of research has shown distinct benefits to being socially involved and not feeling lonely. This can have a profound effect on not only our mental well-being, but also on our physical health as it can reduce your stress hormone levels and lower blood pressure—not to mention, quite simply how long you live. Social isolation is considered a risk factor for both morbidity and mortality.4
But if you don’t come from a large family, don’t worry about it. Your social network certainly doesn’t need to be made up of just your siblings. Extended family, friends, close co-workers, and neighbors can all be an important part of your life and help provide necessary support in the form of socializing, staving off loneliness, and being there for you when you need to talk.
If you feel you might be lacking a little in the good-friends department, work toward building up existing relationships by reaching out beyond social media and asking for face-to-face plans. (Social media does not replace personal contact.) And put yourself out there to meet new people with similar interests by joining a local club or taking a healthy cooking class. You never know where you might find others with whom you’ll click and form truly meaningful relationships.
- 1. You, Wenpeng; et al. "Greater family size is associated with less cancer risk: an ecological analysis of 178 countries." BMC Cancer. 26 September 2018. Accessed 24 October 2018. https://bmccancer.biomedcentral.com/articles/10.1186/s12885-018-4837-0.
- 2. Gaitskell, Kezia; et al. "Histological subtypes of ovarian cancer associated with parity and breastfeeding in the prospective Million Women Study." International Journal of Cancer. 15 January 2018. Accessed 25 October 2018. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5725697/.
- 3. Phipps, Amanda I.; et al. "Reproductive History and Oral Contraceptive Use in Relation to Risk of Triple-Negative Breast Cancer." Journal of the National Cancer Institute. 23 February 2011. Accessed 25 October 2018. https://academic.oup.com/jnci/article/103/6/470/2568727?searchresult=1.
- 4. Cruces J, Venero C, Pereda-Pérez I, De la Fuente M. "The effect of psychological stress and social isolation on neuroimmunoendocrine communication." Curr Pharm Des. 2014;20(29):4608-28. https://www.ncbi.nlm.nih.gov/pubmed/24588822