In a recent study, childhood physical abuse increased the risk of developing cancer by 40%. What are the potential mechanisms? Here are my thoughts:
Traumatic events such as childhood physical abuse may lead to chronic hypothalamic-pituitary-adrenal dysregulation with low cortisol production. This is seen particularly in those suffering from posttraumatic stress disorder or anxiety disorders resulting from childhood abuse.
Impaired adrenal cortical response to stress may lead to a chronically elevated stress signaling, as cortisol helps reduce norepinephrine signaling. Norepinephrine is the most prominent signal for stress.
Increases in norepinephrine signaling lead to insulin resistance. Insulin resistance leads to an increase in insulin production to maintain glucose control and glucose entry into cells. Insulin, however, stimulates cellular growth. Chronically high levels of insulin increases the risk for cancer.
Increases stress signaling may lead to an increase in pro-inflammatory cytokine signaling from brain microglia. The increase in pro-inflammatory cytokine signaling as well as increase norepinephrine signaling increases immune system activity and inflammatory processes. The increase in inflammatory processes may increase oxidative stress which may lead to damage of DNA and cancer.
Childhood abuse also leads to the development of maladaptive or poorly developed mindfulness, distress tolerance, self-nurturing, problem-solving, and relationship skills. Childhood abuse also may disrupt or warp the development of a person’s belief system – the internal analog/model of reality through which the brain filters new sensory input. Objects or persons in the abused person’s environment may have higher perceived threats to self than those in non-abused persons. This may lead to chronically stressful interactions with objects or persons in the environment. Traumatic memories may provide a constant source of stress. One of cortisol’s functions is to enable the brain to ignore distracting emotionally negative memories. But impaired production of cortisol promotes flashbacks instead – since these distressing memories cannot be suppressed or ignored without adequate cortisol production. The sum of these psychological deficits is chronically increased stress signaling and the above-fore-mentioned risks for cancer.
There are severe other mechanisms involved as we go deeper into the biochemistry of the stress response. But the above are a few ideas.
Medline: http://www.ncbi.nlm.nih.gov/pubmed/19472404?
Cancer. 2009 May 26.
Making a link between childhood physical abuse and cancer: results from a regional representative survey.
Fuller-Thomson E, Brennenstuhl S.
Department of Family and Community Medicine, University of Toronto, Toronto, Ontario, Canada.
BACKGROUND:: Abuse in childhood is associated with many negative adult health outcomes. Only 1 study to date has found an association between childhood abuse and cancer. By using a regionally representative community sample, this preliminary study sought to investigate the association between childhood physical abuse and cancer while controlling for 3 clusters of risk factors: childhood stressors, adult health behaviors, and adult socioeconomic status.
METHODS:: Regional data from the Canadian provinces of Manitoba and Saskatchewan were selected from the 2005 Canadian Community Health Survey. Of the 13,092 respondents, 7.4% (n = 1025) reported that they had been physically abused as a child by someone close to them, and 5.7% (95% confidence interval [CI], 4.9-6.6) reported that they had been diagnosed with cancer by a health professional. The regional level response rate was 84%.
RESULTS:: Childhood physical abuse was associated with 49% higher odds (95% CI, 1.10-2.01) of cancer when adjusting for age, sex, and race only. The odds ratio decreased only slightly to 47% higher odds (95% CI, 1.05-1.99) when the model was adjusted for all 3 clusters of risk factors.
CONCLUSIONS:: A significant and highly stable association between childhood physical abuse and cancer was found even when adjusting for 3 clusters of risk factors. Further research focusing on the potential mechanisms linking childhood abuse and cancer is needed. Cancer 2009. (c) 2009 American Cancer Society.
PMID: 19472404 [PubMed – as supplied by publisher]