Early life infections: pathways to prevent adult cancers?

With support from World Cancer Research Fund/Wereld Kanker Onderzoek Fonds, I’m investigating the overlooked links between early life infections and adult cancer risk using unique Danish data resources. This novel research project will yield insights into whether severe acute infections early in life may protect against development of cancer in adulthood – Dr Julie Aarestrup

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Background

Infections play a paradoxical role in the development of cancer; while many chronic infections (long-term infections such as AIDS or chronic hepatits) promote cancer risk, acute infections (short-term illnesses like the flu or respiratory infections) may actually help fight against cancer. Although this inverse relationship between acute infections and cancer has been known for many decades, it’s often overlooked, most likely because previous studies had substantial methodological limitations.

Hypothesis

Severe acute infections in early life are associated with a lower risk of cancer in early adulthood and that these associations depend on infection type, location, timing, frequency, and cancer subtype. Childhood body size and socio-economic status impact these associations in a complex manner.

Aims

Investigate if severe acute infections early in life are linked to risk of cancer in early adulthood.
Identify whether these associations differ by infection type, location, timing and frequency as well as by cancer subtypes.
Examine the impact of childhood body mass index (BMI) and parental socioeconomic status on these associations.

Methods

This research overcame methodological limitations by using a longitudinal design. They included 68,538 people born between 1977 and 1996 from a population-based Copenhagen School Health Records Register. They followed the children from birth and linked them on an individual basis with national registers that include information on hospitalisations and cancer diagnoses, both of which are mandatory to report in Denmark. They also collected information on childhood body size from the health records and on parental socio-economic status from national registers.

Results

The researchers found that people who were hospitalised with an acute infection during the first 2 years of life had a lower risk of being diagnosed with early-onset cancer later in life than people who were not hospitalised. The risk of cancer did not change depending on whether a person was hospitalised one or more times with an infection early in life.

Conclusions

These findings suggest that infections in the first 2 years of life may have a role in reducing the risk of cancer. However, more studies are needed to investigate these associations in other settings as well as examinations of specific infection types and specific cancer forms.

Impact

These findings raise the intriguing possibility that early life infections, which are common and a leading cause of hospitalisation, may play a role in cancer aetiology.