A Sunny Disposition May Protect Against Breast Cancer
Women who are happy and optimistic appear to be less likely to get breast cancer than their gloomier counterparts, according to a case-control study. Action Points
Explain to interested patients that this study found that happiness and optimism may protect against breast cancer.
Point out that the study asked women to recall their feelings from before their breast cancer diagnosis, which may have influenced the findings.
Israeli women ages 25 to 45 who reported a general feeling of happiness were 25% less likely to have breast cancer (OR 0.75, 95% CI 0.64 to 0.86) than other women, Ronit Peled, Ph.D., of Ben-Gurion University of the Negev here, and colleagues reported online in BMC Cancer.
And those who had been exposed to more than one negative life event — for example, the death of a spouse or a serious illness — were significantly more likely to have the disease (OR 1.62, 95% CI 1.09 to 2.40).
“The relationship between happiness and health should be examined in future studies and possible relevant preventive initiatives should be developed,” the researchers said.
Some studies have suggested a link between stressful life events, psychological distress, and cancer, but the connection remains unclear, according to the researchers.
To explore the issue, they undertook a case-control study in women ages 25 to 45 — 255 had been diagnosed with breast cancer at one of six centers in Israel and 367 were healthy and selected from one of two medical centers.
The case patients were significantly older (mean age 40.03 versus 34.77, P<0.001) and more likely to be married (85.1% versus 75%, P=0.002).
All participants were interviewed with the Brief Symptom Inventory — evaluating depression, anxiety, and happiness and optimism — and a Life Event Questionnaire, in which they were asked to recall major stressful life events and their feelings.
Breast cancer patients were asked for information from before their diagnosis (mean time from diagnosis to interview was one year).
Breast cancer patients reported significantly higher depression scores (P=0.04) and significantly lower happiness and optimism scores (P=0.00) compared with the controls.
A greater percentage of breast cancer patients had been exposed to more than one negative life event compared with the controls (52% versus 43.9%), but the difference fell short of statistical significance (P=0.065).
A multivariate analysis showed that having been exposed to more than one major negative life event (P=0.017) and being married (P=0.019) were positively associated and a general feeling of happiness or optimism (P<0.0001) was negatively associated with breast cancer.
Although the researchers did not find any significant associations for individual life events, cumulative exposure was associated with breast cancer.
“In other words, we can carefully say that experiencing more than one meaningful life event (severe and/or mild to moderate) is a risk factor for breast cancer among young women,” the researchers said.
“On the other hand,” they continued, “general feelings of happiness and optimism can play a protective role against the disease.”
The researchers were unable to identify the mechanism of action through which negative life events may influence breast cancer. However, they cited a series of studies showing that psychological stress may contribute to an increase in cancer by modifying cell responses to environmental factors.
“At the same time,” they said, “the mechanism in which the central nerve, endocrine, and immune systems interact and how behavior and/or external events modulate these three complex systems is not fully understood.”
The authors acknowledged some limitations of the study, including the fact that the study population was not representative of the general population, the low participation rate among cases (25%), and the lack of randomized selection of the controls.
In addition, because the women were asked to recall past feelings and events, the results could have been affected by recollection bias.