Self-reported stress and risk of breast cancer

Latent Class Models of Early-life Trauma and Incident Breast Cancer

BACKGROUND

Psychosocial trauma has been hypothesized to influence breast cancer risk, but little is known about how co-occurring traumas-particularly during early life-may impact incidence. We examine the relationship between multiple measures of early-life trauma and incident breast cancer.

METHODS

The Sister Study is a prospective cohort study of US women (n = 50,884; enrollment 2003-2009; ages 35-74). Of 45,961 eligible participants, 3,070 developed invasive breast cancer or ductal carcinoma in situ through 2017. We assessed trauma before age 18 using previously studied measures (cumulative score, individual trauma type, and substantive domain) and a six-class latent variable to evaluate co-occurring traumas. We accounted for missing data using multiple imputation and estimated hazard ratios (HRs) and 95% confidence intervals (CIs) using Cox proportional-hazards models.

RESULTS

Approximately 49% of participants reported early-life trauma. Using the latent class variable approach, breast cancer hazard was higher among participants who had sexual trauma or household dysfunction (HR = 1.1; CI = 0.93, 1.3) or moderate (HR = 1.2; CI = 0.99, 1.4) but not high trauma (HR = 0.66; CI = 0.44, 0.99) compared to low trauma. Breast cancer HRs associated with sexual early-life trauma or household dysfunction were elevated for pre- and postmenopausal breast cancer and by estrogen receptor status. We found no effect modification by race-ethnicity. Estimated effects were attenuated with report of constant childhood social support.

CONCLUSIONS

Breast cancer incidence varied by latent patterns of co-occurring early-life trauma. Models capturing childhood social support and trauma patterning, rather than cumulative or discrete indicators, may be more meaningful in breast cancer risk assessment.

Genetic Variation and Immunohistochemical Localization of the Glucocorticoid Receptor in Breast Cancer Cases from the Breast Cancer Care in Chicago Cohort

BACKGROUND

Glucocorticoid, one of the primary mediators of stress, acts via its receptor, the glucocorticoid receptor (GCR/NR3C1), to regulate a myriad of physiological processes. We measured the genetic variation and protein expression of GCR, and the genes that regulate GCR function or response and examined whether these alterations were associated with breast cancer clinicopathological characteristics.

METHOD

We used samples from a multiracial cohort of breast cancer patients to assess the association between breast cancer characteristics and the genetic variants of single nucleotide polymorphisms (SNPs) in GCR/NR3C1, FKBP5, Sgk1, IL-6, ADIPOQ, LEPR, SOD2, CAT, and BCL2.

RESULTS

Several SNPs were associated with breast cancer characteristics, but statistical significance was lost after adjustment for multiple comparisons. GCR was detected in all normal breast tissues and was predominantly located in the nuclei of the myoepithelial cell layer, whereas the luminal layer was negative for GCR. GCR expression was significantly decreased in all breast cancer tissue types, compared to nontumor tissue, but was not associated with breast cancer characteristics. We found that high nuclear GCR expression was associated with basal cell marker cytokeratin 5/6 positivity.

CONCLUSION

GCR expression is reduced in breast cancer tissue and correlates with the basal cell marker CK5/6.

Qualitative and quantitative analysis of the defensive profile in breast cancer women: A pilot study

This study analyzed the defensive functioning and profile of nine breast cancer women and identifies the differences from other cancer patients (N0) in the way they deal with internal conflicts and stressful situations related to the illness. Patients were interviewed and evaluated using the Defense Mechanisms Rating Scale Q-sort. Mean differences analysis showed that breast cancer patients use more reaction formation, omnipotence, and rationalization and less idealization of others-image and autistic fantasy, compared with other-site cancer patients. From the qualitative analysis of the defensive profile, displacement and repression appeared among the most representative defense mechanisms of breast cancer patients.

Posttraumatic Stress Disorder and Cancer Risk: A Nested Case-Control Study

Data regarding cancer risk for individuals who were exposed to traumatic and stressful life events are conflicting. We sought to evaluate the association between posttraumatic stress disorder (PTSD) and the risk of the four most common solid tumors: lung, breast, prostate, and colorectal cancers. We conducted four nested case-control studies using a large UK population-based database. Cases were defined as individuals with any medical code for the specific malignancy. For every case, we used incidence-density sampling to match four controls by age, sex, practice site, and both duration and calendar time of follow-up. Exposure of interest was any diagnosis of PTSD prior to cancer diagnosis. The odds ratios (ORs) and 95% confidence intervals (CIs) for cancer risk associated with PTSD were estimated using multivariable conditional logistic regression and were adjusted for smoking status, obesity, and antidepressant use. The study population included four case groups according to cancer type. There were 19,143 cases with lung cancer (74,473 matched controls), 22,163 cases with colorectal cancer (86,538 matched controls), 31,352 cases with breast cancer (123,285 matched controls), and 27,212 cases with prostate cancer (105,940 matched controls). There was no statistically significant association between PTSD and cancer risk among any of the cancer types: lung, OR = 0.73, 95% CI [0.43, 1.23]; breast, OR = 0.73, 95% CI [0.52, 1.01]; prostate, OR = 1.24, 95% CI [0.87, 1.77]; and colorectal, OR = 1.05, 95% CI [0.68, 1.62]. Our findings indicated that participants in our study with PTSD were not at increased risk of lung, breast, prostate, and colorectal cancers.

Adjustment disorder and type-specific cancer incidence: a Danish cohort study

BACKGROUND

Although adjustment disorder is common, there is a dearth of research on its physical health consequences. Earlier studies, biological mechanisms and stress-related behaviors suggest that cancer may be a potential sequelae of adjustment disorder. This study examined the association between adjustment disorder and type-specific cancer incidence in a nationwide cohort.

METHODS

Data were obtained from the comprehensive nationwide medical and administrative registries of Denmark. We calculated the incidence of type-specific cancers from 1995 to 2013 in patients with a prior adjustment disorder diagnosis (n = 58,712), and compared it with the incidence in the general population by calculating standardized incidence ratios (SIRs) with accompanying 95% confidence intervals (CIs). SIRs were adjusted using semi-Bayes shrinkage.

RESULTS

The SIR for any type of cancer was 1.0 (95% CI: 0.99, 1.1). Adjustment disorder was associated with a 10% lower rate of immune-related cancers (SIR = 0.9, 95% CI: 0.84, 0.97) and with a 20% higher rate of smoking- and alcohol-related cancers (SIR = 1.2, 95% CI: 1.1, 1.3). We found null associations for hematological (SIR = 1.1, 95% CI: 0.89, 1.3) and hormone-related (SIR = 0.98, 95% CI: 0.91, 1.1) malignancies. After semi-Bayes adjustment, type-specific cancer SIRs indicated no association between adjustment disorder and cancer incidence.

CONCLUSIONS

This study provides persuasive evidence for a null association between adjustment disorder and type-specific cancer incidence in a nationwide study cohort.

Perception matters: Stressful life events increase breast cancer risk

OBJECTIVE

The relationship between psychological stress and breast cancer risk is unclear. The present study sought to understand how stressfulness appraisal of salient Life Events (LEs) influences breast cancer risk.

METHODS

A case-control design was used and included 664 female cases identified through the Cancer Surveillance Program of Orange County, CA and 203 female population-based controls. A LE questionnaire determined if events occurred prior to breast cancer diagnosis and if these events were considered to be stressful or not. Multivariate unconditional logistic regression was used to calculate ORs while adjusting for known breast cancer covariates.

RESULTS

Cumulative adverse LEs perceived as stressful were associated with increased breast cancer risk in a dose response fashion (OR = 1.63, 95% CI = 1.00-2.66, P_trend = 0.045). Conversely, events perceived as non-stressful did not have a significant impact on breast cancer risk. Previous personal illness was directly related to increased breast cancer risk, whether perceived as stressful (OR = 2.84, 95% CI = 1.96-4.11) or non-stressful (OR = 3.47, 95% CI = 1.34-8.94). Abortion and relocation were observed to have a protective effect on breast cancer risk only when reported as stressful (OR = 0.54, 95% CI = 0.32-0.92; OR = 0.63, 95% CI = 0.43-0.93, respectively). Pre/Peri-menopausal women who were nulliparous or who had their first child at ≥30 years of age were especially prone to the effects of appraised stress on increased breast cancer risk.

CONCLUSIONS

This study underscores the importance of stressfulness appraisal when determining the effect of major LEs on breast cancer risk. Our results support incorporating assessments of perceived stressfulness in future epidemiological investigation of this topic.

Psychological stress and breast cancer incidence: a systematic review

Objective

Breast cancer is the world’s leading cause of cancer mortality in women. Stress is an imminent risk factor with a documented negative impact on neuro-endocrine and immune system. Numerous epidemiological studies have investigated the link between stress and cancer, reporting contradictory results from no association to a close causal link. The impact of the topic and the lack of conclusion compelled this systematic review.

Methods

A systematic review was carried out, including all literature studies from 1966 to 2016, investigating the relationship between stress and the occurrence of breast cancer. Of the 1813 articles identified in the PubMed/Medline database, 52 were eligible and included in the analysis.

Results

A number of 17 retrospective, 20 limited prospective and 15 prospective studies were analyzed. The number of patients exceeded 29,000, for a total number of more than 700.000 women recruited from hospital, screening cohorts or population registers. We identified 26 positive articles linking personal traits, stressful events and breast cancer, 18 negative articles that did not confirm their hypothesis and 8 articles that could not be classified. Facing heterogeneity, all possible misguiding factors such as: study design, information gathering, stress type, moment of exposure, individual susceptibility and personality, were discussed independently.

Conclusions

Qualitative analysis of articles has revealed a possible association between stress and cancer, especially regarding stressful life events. In the absence of a meta-analysis and taking into account the methodological heterogeneity of the studies, the results are difficult to interpret and the role of chance is difficult to exclude.

Negative Valence Life Events Promote Breast Cancer Development

BACKGROUND

The influence of stress on breast cancer risk remains unknown. The goal of the present study was to determine the effect of stress in the form of salient positive and negative valence life events (LEs) on primary invasive breast cancer risk. We hypothesized that salient negative LEs would increase breast cancer risk and salient positive LEs would attenuate this increased risk.

PATIENTS AND METHODS

We used a case-control design with 664 cases identified through the Cancer Surveillance Program of Orange County and 203 population-based controls. Participants completed a risk factor questionnaire, which included a LE section. Fourteen salient LEs of positive or negative valence were used to quantify stress exposure. A baseline model was constructed, and odds ratios (ORs) were calculated using multivariate unconditional logistic regression.

RESULTS

Negative LEs were associated with increased breast cancer risk. The OR for ≥ 4 negative LEs showed a 2.81-fold increase in breast cancer risk (OR, 2.81; 95% confidence interval [CI], 1.47-5.36). A significant dose-response relationship between lifetime negative valence LEs and breast cancer risk was found. Previous personal illness increased breast cancer risk by 3.6-fold (OR, 3.60; 95% CI, 2.50-5.20). In contrast, abortion was associated with a 45% decrease in breast cancer risk (OR, 0.55; 95% CI, 0.34-0.89). Salient positive LEs did not have a significant effect on breast cancer risk. However, they seemed to buffer the adverse effect of salient negative LEs on breast cancer risk.

CONCLUSION

The findings from the present study support the role of salient negative LEs in promoting breast cancer development, with a possible buffering effect of salient positive LEs.

Association of striking life events with primary breast cancer in 265 Chinese women: a case-control study

The current case-control study investigated the relationship between striking life events and breast cancer in Chinese women. A total of 265 primary breast cancer patients and 265 controls were enrolled with matching for age and completed questionnaires. Logistic regression analysis was used. Thirty-nine breast cancer patients reported striking life events and twenty-four of the controls reported striking life events. The number of striking life events was significantly greater in patients (p = 0.04). It indicated a striking life event led to a 1.726-fold increased HR (95% CI 1.005-2.965, p < 0.05) for breast cancer with adjustment for age, and a 1.811-fold increased HR (95% CI 1.021 - 3.212, P < 0.05) with adjustment for age, BMI, and late age at menopause. High BMI (OR: 1.680, 95% CI: 1.258-2.196, p < 0.05) and a family history of breast cancer (OR: 2.244, 95% CI: 1.065-4.729, p < 0.05, respectively) increased the risk of breast cancer, and late age at menopause decreased the risk for breast cancer (OR: 0.513, 95% CI: 0.303-0.868, p < 0.05). Our findings indicate a significant association between striking life events and breast cancer in Chinese women, especially in the subpopulation with high BMI or family history of breast cancer.

Prevalence and prognosis of stress disorders: a review of the epidemiologic literature

Given the ubiquity of traumatic events, it is not surprising that posttraumatic stress disorder (PTSD) - a common diagnosis following one of these experiences - is characterized as conferring a large burden for individuals and society. Although there is recognition of the importance of PTSD diagnoses throughout psychiatry, the literature on other diagnoses one may receive following a stressful or traumatic event is scant. This review summarizes the literature on stress disorders (classified according to the International Classification of Diseases, 10th Edition [ICD-10]), including acute stress reaction, PTSD, adjustment disorder and unspecified stress reactions. This review focuses on the literature related to common psychiatric and somatic consequences of these disorders. The prevalence and incidence of each disorder are described. A review of epidemiologic studies on comorbid mental health conditions, including depression, anxiety and substance abuse, is included, as well as a review of epidemiologic studies on somatic outcomes, including cancer, cardiovascular disease and gastrointestinal disorders. Finally, the current literature on all-cause mortality and suicide following stress disorder diagnoses is reviewed. Stress disorders are a critical public health issue with potentially deleterious outcomes that have a significant impact on those living with these disorders, the health care system and society. It is only through an awareness of the impact of stress disorders that appropriate resources can be allocated to prevention and treatment. Future research should expand the work done to date beyond the examination of PTSD, so that the field may obtain a more complete picture of the impact all stress disorders have on the many people living with these diagnoses.

Posttraumatic stress disorder and cancer risk: a nationwide cohort study

The association between stress and cancer incidence has been studied for more than seven decades. Despite plausible biological mechanisms and evidence from laboratory studies, findings from clinical research are conflicting. The objective of this study was to examine the association between PTSD and various cancer outcomes. This nation-wide cohort study included all Danish-born residents of Denmark from 1995 to 2011. The exposure was PTSD diagnoses (n = 4131). The main outcomes were cancer diagnoses including: (1) all malignant neoplasms; (2) hematologic malignancies; (3) immune-related cancers; (4) smoking- and alcohol-related cancers; (5) cancers at all other sites. Standardized incidence ratios (SIR) were calculated. Null associations were found between PTSD and nearly all cancer diagnoses examined, both overall [SIR for all cancers = 1.0, 95 % confidence interval (CI) = 0.88, 1.2] and in analyses stratified by gender, age, substance abuse history and time since PTSD diagnosis. This study is the most comprehensive examination to date of PTSD as a predictor of many cancer types. Our data show no evidence of an association between PTSD and cancer in this nationwide cohort.

Psychological reactivity to laboratory stress is associated with hormonal responses in postmenopausal women

OBJECTIVE

The present study examined associations between psychological reactivity and hormonal responses to a standardized laboratory stressor (Trier Social Stress Test, TSST) in postmenopausal women.

METHODS

Postmenopausal women aged 50-74 years undertook anxiety and mood assessments prior to and following the TSST. Blood samples were drawn at multiple timepoints for assessment of cortisol, adrenocorticotrophic hormone (ACTH) and dehydroepiandrosterone (DHEA).

RESULTS

Forty postmenopausal women completed the assessments. As expected, significant increases in anxiety and negative affect and decreases in positive affect were observed after the TSST; however, the magnitude of change in anxiety and mood varied considerably across individuals. Analyses indicated that greater increases in anxiety and negative affect after the TSST were associated with higher levels of cortisol, ACTH and DHEA after controlling for race, age, body mass index and smoking status. Changes in positive affect were not associated with cortisol, ACTH or DHEA.

CONCLUSIONS

These findings suggest that enhanced reactivity to stress is associated with higher hormone levels among postmenopausal women, which could have potential implications for health.

Striking life events associated with primary breast cancer susceptibility in women: a meta-analysis study

Purpose

The association between striking life events, an important stress and acute anxiety disorder, and the occurrence of primary breast cancer is unclear. The current meta-analysis was designed to assess the relationship between striking life events and primary breast cancer incidence in women.

Methods

Systematic computerized searching of the PubMed, ScienceDirect, Embase, and BMJ databases with the combinations of controlled descriptors from Mesh, including breast cancer, breast tumor, cancer of breast, mammary carcinoma, life events, life change events, case–control studies, case-base studies, cohort study, and cohort analysis and identified a total of 307 papers published from January 1995 to April 2012. Following evaluation of methodological quality with the Downs & Black criteria, seven case–control or cohort studies were selected and the association between striking life events and primary breast cancer incidence in women was measured using random effect or fixed-effect odds ratios combined with 95% confidence interval.

Results

The seven studies included in the final meta-analysis included 99,807 women. A meta-analysis showed that the pooled OR for striking life events and breast cancer was 1.51 (95% CI 1.15 - 1.97, P = 0.003), indicating that women with striking life events were at 1.5-fold greater risk of developing breast cancer. The pooled OR for severe striking life events and breast cancer was 2.07 (95% CI 1.06 - 4.03), indicating that women with severe striking life events were at 2-fold greater risk of developing breast cancer.

Conclusions

The current meta-analysis showed significant evidence for a positive association between striking life events and primary breast cancer incidence in women.

Self-reported psychological stress and the risk of breast cancer: a case-control study

The aim of this study was to examine the relationship between severe life events and breast cancer risk. This study was based on a case-control examination of 858 Polish invasive breast cancer cases and 1085 controls matched for age and place of residence. Data on life events, sociodemographic characteristic, reproductive factors, family history of breast cancer, current weight and height, and lifestyle habits were collected between January 2003 and May 2007 using a self-administered questionnaire. Odds ratios with 95% confidence intervals were estimated as the measure of the relationship between life event stress and breast cancer risk using unconditional logistic regression analyses. After adjustment for potential breast cancer risk factors, women with four to six individual major life events had 5.33 times higher risk for breast cancer, compared with those in the lowest quartile. Similarly, women with a lifetime life change score greater than 210 had about 5 times higher risk compared to women with corresponding scores in the range 0-70. Several life events (death of a close family member, personal injury or illness, imprisonment/trouble with the law, retirement) were significantly associated with breast cancer risk. These findings suggest that major life events can play an important role in the etiology of breast cancer.

Glucocorticoid receptor and breast cancer

Stress enhances glucocorticoid (GC) synthesis, which alters inflammation and immune responses, as well as cellular proliferation and apoptosis in a number of tissues. Increasingly, stress has been associated with cancer progression, and in particular in breast cancer. Consequently, an operational glucocorticoid receptor system in breast tissue influences breast cancer development. In this review, we summarize the data on the GC/GR system in normal and tumoral breast tissue. We also review the molecular mechanisms by which GCs control apoptosis and proliferation in breast cancer models and how GCs alter the chemotherapy of breast cancer treatment when used in combination. Finally, we discuss the participation of GR in breast tumorigenesis under hormone replacement therapy.

Association between stress and breast cancer in women: a meta-analysis

The objective of the current meta-analysis was to verify the association between stressful life events and primary breast cancer incidence in women. A total of 618 studies from 1982-2007 were found in the PubMed, LILACS, and Cochrane Library databases. Methodological quality was evaluated according to the Downs & Black criteria. Eight studies were selected (six case-controls and two cohorts). The studies were grouped in three analyses, two of which based on the categories widowhood and divorce and the other based on self-rated intensity and frequency of stressful events. Relative risks were: widowhood 1.04 (95%CI: 0.75-1.44; p = 0.800); divorce 1.03 (95%: 0.72-1.48; p = 0.850); and intensity/frequency of stress 1.73 (95%CI: 0.98-3.05; p = 0.059). We conclude that stressful life events as a whole are not associated with risk of breast cancer in women. However, it is not possible to rule out high-intensity stress as a risk factor for breast cancer.

Is cancer risk associated with anger control and negative affect? Findings from a prospective cohort study

OBJECTIVE

To examine the associations between anger control and negative affect and the risk of five common cancers and total cancers. Possible associations between emotional states and the risk of cancer have long been postulated.

METHODS

Prospective cohort study with average follow-up of 9 years. A total of 19,730 adults (99% aged between 40 and 69 years) answered questions on negative affect and anger control at baseline. A total of 1952 cancers were diagnosed, including 352 breast cancers, 318 prostate cancers, 88 lung cancers, 280 colorectal cancers, and 261 melanomas.

RESULTS

After adjustment for potential confounders, there was no significant association between anger control or negative affect and risk of breast cancer, melanoma, or total cancers. Weak associations were identified between anger control and prostate cancer, hazards ratio (HR) 1.17 (1.04-1.30) for a 1-unit increase in the standardized scale, negative affect, and lung cancer, HR 1.24 (1.01-1.52) and colorectal cancer, HR 1.14 (1.01-1.28). There was no evidence of an interaction effect between anger control and negative affect.

CONCLUSIONS

Results suggest that anger control and negative affect are not associated with breast cancer, melanoma, or total cancer risk, although they may have a small role in risk of prostate, colorectal, and lung cancer. Although more research is needed to confirm these latter associations, the results suggest that if affective states are associated with cancer development, the association may differ for different cancers and argue against the use of total cancer as an outcome measure for studies in this area.

Stress and depression-induced immune dysfunction: implications for the development and progression of cancer

The persistent activation of the hypothalamic-pituitary-adrenal axis and the sympathetic-adrenal-medullary axes in chronic stress response and in depression impairs the immune response and contributes to the development and progression of some types of cancer. This overview presents results from experimental animal models, human studies, and clinical evidence that various cellular and molecular immunological parameters are compromised in chronic stress and depression. At the cellular level, stressed and depressed patients had overall leukocytosis, high concentrations of circulating neutrophils, reduced mitogen-stimulated lymphocyte proliferation and neutrophil phagocytosis. At the molecular level, high levels of serum basal cortisol, acute phase proteins, specific antibodies against herpes simplex virus type 1 and Epstein Barr virus, plasma concentration of interleukins IL-1, IL-6, and TNF-alpha, and a shift in the balance of Th1 and Th2 immune response were observed. Both stress and depression were associated with the decreased cytotoxic T-cell and natural killer cell activities affecting the processes of the immune surveillance of tumours, and the events that modulate the development and the accumulation of somatic mutations and genomic instability. DNA damage, growth and angiogenic factors, proteases, matrix metalloproteinases, and reactive oxygen species were also related to the chronic stress response and depression. Behavioural strategies, psychological, and psychopharmacotherapeutic interventions that enhance effective coping and reduce affective distress showed beneficial effects in cancer patients. A better understanding of the bidirectional communication between the neuroendocrine and immune systems could contribute to novel clinical and treatment strategies in oncology.

Cancer attributions, distress, and health practices among gynecologic cancer survivors

OBJECTIVE

Personal beliefs about one's medical condition have been related to health behaviors and psychological distress among individuals with serious illness. We examined whether beliefs about cause of cancer and prevention of recurrence were associated with health practices and distress in 134 long-term endometrial and cervical cancer survivors.

METHODS

Participants completed questionnaires assessing depressive symptoms, anxiety, health behavior, and beliefs about factors that may have caused their cancer and prevented recurrence.

RESULTS

Genetics/heredity was rated as the most important cancer cause, followed by stress, God's will, hormones, and environmental factors. Medical screening was rated as most important in preventing recurrence, followed by positive attitude and prayer. Stronger causal attributions were generally associated with elevated depressive symptomatology and anxiety, but women citing potentially controllable causes were more likely to be practicing healthy behaviors. Similarly, women citing health behaviors as important in preventing recurrence reported greater anxiety but were more likely to practice positive health behaviors. Health behavior and lifestyle attributions interacted with health practices in predicting distress. For example, among women who had not made positive dietary changes, rating lifestyle as important in preventing recurrence was associated with greater distress, whereas among women who had made a positive change in diet, this belief was associated with less distress.

CONCLUSIONS

Results suggest that stronger attributions are associated with greater distress, but engaging in behavior believed to be important in preventing cancer or recurrence may ameliorate this distress.

Depressive symptoms and development of coronary heart disease events: the Italian longitudinal study on aging

BACKGROUND

Studies on the association between depressive symptomatology (DS) and cardiovascular events and mortality in elderly persons have yielded contradictory findings. To address this issue, the authors assessed DS and an extensive array of sociodemographic, behavioral, and biological variables in the largest population-based sample of older Italians ever studied and analyzed their association with coronary heart disease (CHD) morbidity and total number of deaths.

METHODS

This prospective, community-based cohort study included a sample of 5632 Italians, 65 years and older, who were recruited from the demographic registries of eight municipalities in Italy. Depressive symptomatology was assessed using the Geriatric Depression Scale, and a score > or =10 was used to indicate the presence of DS. All traditional cardiovascular disease risk factors were assessed at baseline, through questionnaires, blood tests, and physical examinations. The outcomes were CHD fatal and nonfatal events and total number of deaths. The association of the predictive variables with the outcomes was assessed using different Cox models.

RESULTS

Baseline DS was associated with a higher incidence of fatal and nonfatal CHD events (hazard ratio [HR], 1.66; 95% confidence interval [CI], 1.06-2.60) and with cardiovascular mortality in men (HR, 2.49; 95% CI, 1.60-3.87) and with total mortality in men (HR, 2.02; 95% CI, 1.58-2.58) and women (HR, 1.43; 95% CI, 1.04-1.95) at the 4-year follow-up assessment. This association was observed after adjusting for a vast array of potential confounding variables, including major chronic conditions.

CONCLUSIONS

Depressive symptomatology confers an increased risk for CHD in men and for total mortality in men and women but is not explained by health behaviors, social isolation, or biological or clinical determinants.

Stress, depression, the immune system, and cancer

The links between the psychological and physiological features of cancer risk and progression have been studied through psychoneuroimmunology. The persistent activation of the hypothalamic-pituitary-adrenal (HPA) axis in the chronic stress response and in depression probably impairs the immune response and contributes to the development and progression of some types of cancer. Here, we overview the evidence that various cellular and molecular immunological factors are compromised in chronic stress and depression and discuss the clinical implications of these factors in the initiation and progression of cancer. The consecutive stages of the multistep immune reactions are either inhibited or enhanced as a result of previous or parallel stress experiences, depending on the type and intensity of the stressor and on the animal species, strain, sex, or age. In general, both stressors and depression are associated with the decreased cytotoxic T-cell and natural-killer-cell activities that affect processes such as immune surveillance of tumours, and with the events that modulate development and accumulation of somatic mutations and genomic instability. A better understanding of the bidirectional communication between the neuroendocrine and immune systems could contribute to new clinical and treatment strategies.

The association between stressful life events and breast cancer risk: a meta-analysis

Breast cancer is the most prevalent cancer in women in Western societies. Studies examining the relationship between stressful life events and breast cancer risk have produced conflicting results. The purpose of this meta-analysis was to identify studies on this relationship, between 1966 and December 2002, to summarize and quantify the association and to explain the inconsistency in previous results. Summary odds ratios and standard errors were calculated, using random effect meta-regression analyses, for the following categories: stressful life events, death of spouse, death of relative or friend, personal health difficulties, nonpersonal health difficulties, change in marital status, change in financial status and change in environmental status. The presence of publication bias has been explored, and sensitivity analyses were performed to identify heterogeneity, using calculation of the percentage of variability due to heterogeneity, meta-regression analyses and stratification. Only the categories stressful life events (OR = 1.77, 95% CI 1.31-2.40), death of spouse (OR = 1.37, 95% CI 1.10-1.71) and death of relative or friend (OR = 1.35, 95% CI 1.09-1.68) showed a statistically significant effect. Publication bias was identified in both stressful life events (p = 0.00) and death of relative or friend (p = 0.02). Sensitivity analyses resulted in the identification of heterogeneity in all categories, except death of spouse. The results of this meta-analysis do not support an overall association between stressful life events and breast cancer risk. Only a modest association could be identified between death of spouse and breast cancer risk.

Psychological stress and the risk of breast cancer: a case–control study

OBJECTIVE

To determine whether psychological stress, in the form of past life events and stress at work, was associated with the development of breast cancer.

METHODS

The study was based on a case-control study of 257 women with breast cancer operated during 1993-1998 in Szczecin (Poland) hospitals and 565 controls, free of any cancer diagnosis. The subjects were sent a detailed questionnaire including questions on sociodemographic data; lifestyle (lifetime recreational and sport activities, occupational physical activity, diet); reproductive history; experience of psychological stress. The subjects reported major stressful life events, stress of daily activity and experience of stress at work. Logistic regression analyses were used to estimate the odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

After adjustment for age and other potential confounders, we found that women with major life events, stress of daily activity, and depression had 3.7 times higher risk for breast cancer, compared to those which did not experience such stress (OR = 3.70; 95% CI, 2.61-5.26). Women who reported experience of stress at work had a nonsignificant 16% higher risk for breast cancer compared with those who reported no stress (OR = 1.16; 95% CI, 0.82-1.64). A higher proportion of cases (89.1%) than controls (71.1%) reported that their job was stressful, very fretful or very responsible or experienced a major life event (OR = 4.29; 95% CI, 2.66-6.92).

CONCLUSION

These findings suggest an association between major life events and breast cancer.

Maternal breast cancer risk after the death of a child

The possible association between a severe traumatic life event (death of a child) and breast cancer risk was examined in a case-control study nested within a nation-wide cohort in Sweden. Our study population included 27,571 women with breast cancer and 141,798 control women born between 1925-1976. After adjustment for age, parity, age at first birth and education, the overall risk estimate for breast cancer among all women that had experienced the death of a child was 1.05 (95% confidence interval [CI] = 0.96-1.15). Among uniparous women the corresponding odds ratio (OR) was 1.27 (95% CI = 0.98-1.64). When stratifying for child's age at death a significant risk increase was detected among women that had lost their only child when the child was between 1-4 years of age (OR = 2.65; 95% CI = 1.06-6.60). These findings do not support an overall increase in breast cancer risk after the death of a child, a severe traumatic life event. Based on a small number of subjects, our finding of an increased risk in a subgroup of uniparous women losing their only child could be due to chance.

Self-reported stress levels predict subsequent breast cancer in a cohort of Swedish women

The association between stress and breast cancer has been studied, mostly using case-control designs, but rarely examined prospectively. The purpose of this paper is to describe the role of stress as a predictor of subsequent breast cancer. A representative cohort of 1,462 Swedish women aged 38-60 years were followed for 24 years. Stress experience at a baseline examination in 1968-69 was analysed in relation to incidence of breast cancer with proportional hazards regression. Women reporting experience of stress during the five years preceding the first examination displayed a two-fold rate of breast cancer compared with women reporting no stress (age-adjusted relative risk 2.1; 95% CI [1.2-3.7]). This association was independent of potential confounders including reproductive and lifestyle factors. In conclusion, the significant, positive relationship between stress and breast cancer in this prospective study is based on information that is unbiased with respect to knowledge of disease, and can be regarded as more valid than results drawn from case-control studies.

Attachment experiences in women with breast cancer

Research into relational experiences of cancer patients suggests possible links between attachment processes and cancer. Women with and without breast cancer were assessed regarding attachment history and early loss, closeness to parents, and adult attachment. Women with breast cancer reported significantly higher incidences of insecure histories and early loss, and scored significantly higher on avoidant attachment than women without cancer. The women in the cancer group also scored significantly lower on closeness to parents than women in the noncancer group. These findings are preliminary and indicate that more research is needed to understand the role that attachment may play in a multidimensional, biopsychosocial model of cancer.

Stress of daily activities and risk of breast cancer: a prospective cohort study in Finland

The belief that life stress enhances breast cancer is common, but there are few prospective epidemiological studies on the relationship of life stress and breast cancer. We have investigated the association between stress of daily activities (SDA) and breast-cancer risk in a prospective cohort study of 10,519 Finnish women aged 18 years or more. SDA measures a subject's own appraisal of daily stress. It was assessed in 1975 and 1981 by a self-administered questionnaire, which also provided information on subject characteristics and other known breast-cancer risk factors. Follow-up data for breast cancer from 1976 to 1996 were attained through record linkage to the Finnish Cancer Registry. Study subjects were divided into 3 groups based on their SDA scores in 1975: no stress (23% of subjects), some stress (68%) and severe stress (9%). Hazard ratios (HRs) and respective 95% confidence intervals (CIs) for incidence of breast cancer by level of SDA were obtained from the Cox proportional hazards model. We identified 205 incident breast cancers in the cohort. Multivariable-adjusted HRs for breast-cancer risk were 1.00 (reference), 1.11 (95% CI 0.78-1.57) and 0.96 (95% CI 0.53-1.73) by increasing level of stress. Neither shifting of the SDA cut-off points nor restricting the analysis to women who reported the same level of SDA in 1975 and 1981 materially altered the results. We found no evidence of an association between self-perceived daily stress and breast-cancer risk.

Cancer incidence and survival following bereavement

OBJECTIVES

This study investigated the effect of parental bereavement on cancer incidence and survival.

METHODS

A cohort of 6284 Jewish Israelis who lost an adult son in the Yom Kippur War or in an accident between 1970 and 1977 was followed for 20 years. We compared the incidence of cancer in this cohort with that among nonbereaved members of the population by logistic regression analysis. The survival of bereaved parents with cancer was compared with that of matched controls with cancer.

RESULTS

Increased incidence was found for lymphatic and hematopoietic malignancies among the parents of accident victims (odds ratio [OR] = 2.01; 95% confidence interval [CI] = 1.30, 3.11) and among war-bereaved parents (OR = 1.47; 95% CI = 1.13, 1.92), as well as for melanomas (OR = 4.62 [95% CI = 1.93, 11.06] and 1.71 [95% CI = 1.06, 2.76], respectively). Accident-bereaved parents also had an increased risk of respiratory cancer (OR = 1.50; 95% CI = 1.07, 2.11). The survival study showed that the risk of death was increased by bereavement if the cancer had been diagnosed before the loss, but not after.

CONCLUSIONS

This study showed an effect of stress on the incidence of malignancies for selected sites and accelerated demise among parents bereaved following a diagnosis of cancer, but not among those bereaved before such a diagnosis.

Epidemiological evidence for a relationship between life events, coping style, and personality factors in the development of breast cancer

OBJECTIVE

Review empirical evidence for a relationship between psychosocial factors and breast cancer development.

METHODS

Standardised quality assessment criteria were utilised to assess the evidence of psychosocial predictors of breast cancer development in the following domains: (a) stressful life events, (b) coping style, (c) social support, and (d) emotional and personality factors.

RESULTS

Few well-designed studies report any association between life events and breast cancer, the exception being two small studies using the Life Events and Difficulties Schedule (LEDS) reporting an association between severely threatening events and breast cancer risk. Seven studies show anger repression or alexithymia are predictors, the strongest evidence suggesting younger women are at increased risk. There is no evidence that social support, chronic anxiety, or depression affects breast cancer development. With the exception of rationality/anti-emotionality, personality factors do not predict breast cancer risk.

CONCLUSION

The evidence for a relationship between psychosocial factors and breast cancer is weak. The strongest predictors are emotional repression and severe life events. Future research would benefit from theoretical grounding and greater methodological rigour. Recommendations are given.

A prospective study of job strain and risk of breast cancer

BACKGROUND

There is conflicting evidence on whether stress is a risk factor for breast cancer. The present study examined prospectively the relationship between stress at work and risk of breast cancer.

METHODS

Participants comprised 26 936 postmenopausal women in the Nurses' Health Study ages 46-72 who were in paid employment, and who had no previous history of cancer. Multivariate-adjusted regression analysis was used to examine the relationship between job strain (measured by the Karasek Job Content Questionnaire in 1992) and risk of incident invasive and in situ breast cancer.

RESULTS

From 1992 through 1994, 219 women were diagnosed with breast cancer. No evidence was found for a relationship between job stress and risk of breast cancer. Compared with women in low strain jobs, the multivariate-adjusted relative risks of breast cancer were RR = 0.78 (95% CI : 0.52-1.16) for high-strain jobs; RR = 0.76 (95% CI : 0.49-1.17) for active jobs; and RR = 0.94 (95% CI : 0.67-1.34) for passive jobs. Although job strain was related to less breast cancer screening among women in highly demanding jobs, it was not associated with tumour size.

CONCLUSIONS

Job stress was not related to an increase in the incidence of breast cancer in the present cohort of nurses.

Breast cancer risk among women with psychiatric admission with affective or neurotic disorders: a nationwide cohort study in Denmark

There is a considerable interest in the possible relationship between psychosocial factors and the onset of breast cancer. This cohort study was based upon two nationwide and population-based central registers: The Danish Psychiatric Central Register, which contains all cases of psychiatric admissions, and The Danish Cancer Registry, which contains all cases of cancer. The register-linkage was accomplished by using a personal identification number. The study population comprised all women admitted to psychiatric departments or psychiatric hospitals in Denmark between 1969 and 1993 with an affective or a neurotic disorder. Overall, 66,648 women comprising 199,910 admissions and 775,522 person-years were included. The incidence of breast cancer in the cohort was compared with the national breast cancer incidence rates adjusted for age and calendar time. In all, 1270 women with affective or neurotic disorders developed breast cancer subsequent to the first admission as compared with the 1242 women expected, standardized incidence ratio (SIR) = 1.02 (95% confidence interval 0.97-1.08). None of the hypothetical risk factors: type of diagnosis, age or calendar period at cohort entry, age at breast cancer, alcohol abuse, alcohol/drug abuse without further specification, total number of admissions, total length of admissions, or time from first admission showed a statistically significant effect on the relative risk of breast cancer. We found no support for the hypothesis that women admitted to a psychiatric department with an affective or a neurotic disorder subsequently have an increased risk of breast cancer.

Psychosocial factors in the etiology of breast cancer: review of a popular link

Breast cancer is the most frequently occurring type of cancer in women in the western world. The etiology of a large proportion of breast cancers is still unexplained, and the possibility that psychosocial factors could play a role is not ruled out. Already in pre-Christian times, it was assumed that psychological factors might play a significant role in the development of breast cancer. However, studies have failed to produce conclusive results. There is still a lack of knowledge on the relationship between breast cancer development and psychosocial factors such as stressful life events, coping styles, depression, and the ability to express emotions. The results of this review show that there is not enough evidence that psychosocial factors like 'ways of coping' or 'non-expression of negative emotions', play a significant role in the etiology of breast cancer.

Estrogen-regulated non-reproductive behaviors and breast cancer risk: animal models and human studies

The possible role of personality patterns and psychosocial factors in breast cancer has been studied extensively, through both human and animal experiments. The data are conflicting, and the conclusions controversial. This review will serve two purposes. First, we present evidence that behavioral patterns most commonly linked to breast cancer risk are at least partly regulated by estrogens. This section will suggest that some estrogen-regulated behaviors may be markers of increased breast cancer risk. Second, we will briefly review recent findings in animals connecting psychosocial factors to cancer. We also will address the plausible biological mechanisms. The literature suggests that estrogens, particularly when exposure occurs during the critical developmental periods, such as in utero, puberty, pregnancy, and menopause, influence affective behaviors and increase breast cancer risk. The affective behaviors include depression, aggression, and alcohol intake. Thus, psychosocial and personality factors do not necessarily have a direct impact on breast cancer risk; instead, estrogens have a dual effect on behavior and on the breast.