Childhood abuse is often discussed in terms of emotional pain, mental health issues, and relationship difficulties later in life. A new study suggests that its effects may extend into other aspects of health, with serious consequences.
“This study is part of an important and growing evidence base that makes the case that what happens in our childhood matters,” says Katie Ports, PhD, principal researcher at AIR, a nonpartisan, not-for-profit organization that conducts behavioral and social science research, who was not involved in this research.
“Childhood experiences, positive and negative, lay the foundation for subsequent health and well-being,” says Dr. Ports.
Researchers Looked at Different Types of Childhood Abuse
The study included data from 2,636 Canadians ages 65 and older who took part in a nationwide survey on mental health and access to care.
Subjects were survivors of different kinds of childhood adversity:
- Childhood physical abuse
- Childhood exposure to parental domestic violence
- Childhood sexual abuse
The researchers further split childhood sexual abuse into two categories: unwanted sexual touching or fondling, and more severe sexual violence involving coercion, threats, restraint, or physical harm.
The scientists then adjusted their analysis for a long list of factors that could also shape cancer risk, including sex, race, immigrant status, marital status, education, income, smoking status, physical activity, alcohol and drug problems, chronic pain, social support, spirituality, and other chronic health conditions.
Key study findings:
- Overall, 21 percent of subjects reported a cancer diagnosis.
- Of those who reported childhood exposure to parental domestic violence, 27 percent reported a cancer diagnosis.
- Of those who reported childhood physical abuse, 28 percent reported a cancer diagnosis.
- Of those who reported childhood sexual violence with coercion, 35.5 percent reported a cancer diagnosis.
Could Survivors’ Behaviors and Habits Explain Their Increased Cancer Risk?
Investigators thought that adult behaviors and habits would explain the link — but it didn’t.
“We know that people who have experienced childhood abuse are more likely to leave school earlier, have lower income in adulthood, smoke, and struggle with alcohol or drugs,” says senior author Esme Fuller-Thomson, PhD, professor and director of the Institute for Life Course and Aging at the University of Toronto.
Because those factors are linked to higher cancer risk, it seemed reasonable that they might help explain the connection between childhood sexual abuse and cancer in later life, says Dr. Fuller-Thompson.
“However, when we accounted for all of these factors in our analyses, they did not explain the association. The link between childhood sexual abuse and cancer looked very similar before and after. That suggests these adult factors are not the main explanation for what we are seeing,” she says.
How Could Childhood Abuse, Especially Sexual Abuse, Affect Cancer Risk So Much?
Because it was an observational study, the research can’t directly prove that childhood sexual abuse caused cancer. But the findings support a growing body of research that suggests that severe early trauma may affect the body’s stress, immune, and inflammatory systems over time, the authors wrote.
While some stress or adversity is a healthy part of brain development, repeated childhood exposure to adversity, called toxic stress, can result in a stress response that is wired to be on high alert all the time, explains Ports.
This “being on all the time” can compromise the way a child’s brain develops. “Because their brain is focused on dealing with stress, it interferes with other developmental milestones — social, emotional and cognitive learning, and physiological responses,” she says.
These impairments can impact gene expression, brain function, and immune function, as well as behaviors or coping strategies that one adopts to deal with toxic stress, says Ports.
“This change in the pathways linking childhood trauma and cancer may be due to a phenomenon called biological embedding,” says Fuller-Thomson. Adults who were abused as children often have higher levels of chronic inflammation years later. Long-term changes in stress hormones, immune function, and inflammatory responses could help explain why severe trauma is connected to poorer health decades later, she says.
But the link to specific outcomes, such as different cancers, isn’t well understood.
The Findings Add to a Growing Body of Research
The new results fit with earlier robust research linking childhood sexual abuse to poorer health much later in life, says Fuller-Thomson.
“In our previous research, childhood sexual abuse has also been associated with the development of heart disease, stroke, arthritis, asthma, COPD, diabetes, depression, and disability. These patterns show up too consistently to ignore,” she says.
The study does have limitations. It relied on self-reported cancer diagnoses and retrospective reports of childhood adversity, did not look at specific cancer types, and could not account for every factor that might matter, including body mass index, genetic predisposition, childhood poverty, or more detail about the abuse itself.
What These Findings Could Mean for Care
Childhood experiences, positive and negative, lay the foundation for subsequent health and well-being, says Ports.
“If we care about adult health outcomes, we also must care about childhood. Preventing adverse childhood experiences such as child sexual abuse and promoting positive experiences is everyone’s responsibility,” she says.
The message here is not that childhood trauma dooms someone to cancer, says Fuller-Thompson.
“Most survivors of childhood abuse don’t get cancer — this research is about risk, not destiny,” she says.
What the findings do suggest is that trauma history may be another important part of a person’s long-term health story. That is one reason that trauma-informed care matters in cancer prevention and treatment, says Fuller-Thomson.
When a healthcare team understands that a patient’s past may shape how they engage with screening, prevention, and treatment, care can become more supportive and responsive.
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