We know that to reduce the risk of cancer we must stop smoking, stay in shape and get enough sleep. But what if a lot of what causes cancer actually happened in the first few years of our lives?
We know what we need to do to reduce the risk of cancer, right? Quit smoking, avoid processed foods, get fit, lose weight and get enough sleep. But what if much of what causes cancer actually happened in our early years, or worse, before we were even born?
A recent study from Brigham and Women’s Hospital and Harvard University says this may be the case, especially in cancers that occur before age 50 (early-onset cancers).
The most important finding of this study, published in Nature Reviews Clinical Oncology, is that people born after 1990 are more likely to develop cancer before age 50 than people born in, say, 1970. That is, they will be younger. . are more affected by cancer than previous generations, affecting health care, the economy and families.
Eating Habits are Formed Early in Life
Factors we experience early in life can influence cancer risks later in life, and this review of cancer trends looks at how these factors influence early-onset cancers. It’s still not entirely clear which exposures are important in the early years of life, but the main factors are diet, lifestyle, environment and the bugs that live in our gut (the microbiome).
Looking at large numbers of people, researchers can see that eating and lifestyle habits are formed early in life. This is seen in obesity, where obese children are more likely to become obese. Since obesity is a known risk factor for cancer, it follows that these adults are more likely to develop cancer at a younger age, possibly because they have been exposed to the risk factor longer.
Of course, some of these cancers are caught early thanks to early screening and diagnosis programs, which contributes to the growing number of new cancers diagnosed each year around the world. But this is not all.
Early-onset cancers have a different genetic signature than late-onset cancers and are more likely to spread than cancers diagnosed later in life. This means that these types of cancer may need different types of treatment and a more personalized approach tailored to the patient’s age at the time the cancer developed.
Gut Bacteria Altered by Sugar and Antibiotics
Brigham’s study looked at 14 types of cancer and found that the genetic makeup of the cancer, the aggressiveness and growth of the cancer were different in patients who developed the cancer before age 50 compared to those who developed the same cancer after age 50.
This appears to be more pronounced in several types of bowel cancer (colon, rectum, pancreas and stomach). One possible cause is related to diet and the microbiome.
Intestinal bacteria are altered by diets high in sugar, antibiotics and breastfeeding. And as patterns of these things change in a community over time, so do the bacteria in our gut. This could support the introduction of sugar taxes as recommended by the World Health Organization.
If our healthy cells are programmed in utero, the cells that end up in them can also lead to cancer. Maternal diet, obesity, and environmental exposures such as air pollution and pesticides are known to increase the risk of chronic diseases and cancers.
On the contrary, severe restrictions on food intake during pregnancy, as seen in starvation, increase the risk of breast cancer in the offspring. Both results will have different implications for societal approaches to reducing cancer risk.
Understanding what causes early cancers, which exposures really matter, and what can be done to prevent them are some of the first steps in developing prevention strategies for future generations.
As a hematologist, I care for patients with multiple myeloma, an incurable blood cancer that usually affects patients over the age of 70. In recent years, the number of young people diagnosed with this cancer has increased worldwide, which is only partially explained by better detection. This study points to obesity as an important risk factor for early disease, but there are clearly other risk factors yet to be discovered.
