Stress and breast cancer: a systematic update on the current knowledge

Pregnancy, abortion, and birth control methods' complicity with breast cancer occurrence

Reproductive factors play significantly important roles in determining the breast cancer (BC) risk. The impact of pregnancy, abortion, and birth control methods on tumor development remains unclear. It has been found that early full-term pregnancies in young women can lower their lifetime risk of developing the type of cancer in question. However, having a first full-term pregnancy at an older age can increase this risk. The relationship between pregnancy and breast cancer (BC) is, however, much more complicated. Both induced and spontaneous abortions lead to sudden changes in hormonal balance, which could cause different effects on sensitive breast epithelial cells, making abortion a potential risk factor for breast cancer. The influence of hormonal contraception on carcinogenesis is not comprehensively understood, and therefore, more exhaustive analysis of existing data and further investigation is needed. This review explores how the mentioned reproductive factors affect the risk of breast cancer (BC), focusing on the molecular mechanisms that contribute to its complexity. By comprehending this intricate network of relationships, we can develop new strategies for predicting and treating the disease.

Stressful Life Events, Social Support, and Incident Breast Cancer by Estrogen Receptor Status

Chronic stress affects immune function and hormonal signaling and has been hypothesized to be associated with breast cancer, although results from the few prior studies are mixed and have not examined potential differences by estrogen receptor (ER) status. Using the Women's Health Initiative study, we included 76,951 postmenopausal women followed for events for a median of 16.7 years to investigate the association between baseline self-reported stressful life events and incident breast cancer by ER status and whether the association was modified by social support. We generated Cox proportional hazards models adjusting for demographic, clinical, lifestyle/behavioral, and social factors to estimate HRs and 95% confidence intervals (95%CI). The mean age was 63 (SD, 7.3), and majority of participants were White race (83.5%) and married or in a marriage-like relationship (63.0%). In analyses stratified by ER status, there was no relationship between stressful life events and ER-positive breast cancer. In contrast, compared with women in the lowest quartile, those in higher quartiles had an increased risk of ER-negative breast cancer, where those in quartile 4 had the highest risk (Quartile 4 vs. Quartile 1; HR = 1.30; 95%CI, 1.01-1.68; Ptrend = 0.050). Moreover, associations were stronger for the highest versus lowest quartile of stressful life events among widowed women (HR = 2.39; 95%CI, 1.29-4.44; Pinteraction<0.001). Association between stressful life events and ER-negative breast cancer was not modified by social support. In this cohort of postmenopausal women, higher experiences of prediagnostic stressful life events were associated with increased risk of ER-negative breast cancer.

PREVENTION RELEVANCE

Epidemiologic studies on the association between psychosocial stress and breast cancer risk remain inconsistent, while investigation of whether the association differs by ER status is limited. In this prospective cohort of postmenopausal women, high experiences of stressful life events were positively associated with ER-negative disease but not ER-positive.

Stress-related disorders and subsequent cancer risk and mortality: a population-based and sibling-controlled cohort study in Sweden

Prior research has suggested a potential role of psychological stress on cancer development while the role of familial factors on this association is underexplored. We conducted a nationwide cohort study including 167,836 individuals with a first-onset stress-related disorder (including post-traumatic stress disorder, acute stress reaction, adjustment disorder and other stress reactions) diagnosed between 1981 and 2016 in Sweden (i.e., exposed patients), 1,631,801 birth year- and sex-matched unexposed individuals, and 179,209 unaffected full siblings of the exposed patients. Cox models were used to estimate the hazard ratios (HRs) of newly diagnosed cancer and cancer-related death, beyond 1 year after diagnosis of stress-related disorders. We further examined the potential mediation roles of behavior-related morbidities in the associations of stress-related disorders with smoking or alcohol-related cancer incidence and mortality. We found modestly elevated risks of cancer incidence and mortality among exposed patients compared with matched unexposed individuals (incidence: HR = 1.03, 95% CI 1.01–1.06; mortality: HR = 1.13, 95% CI 1.07–1.18), while not when comparing with full siblings (incidence: HR = 1.03, 95% CI 0.99–1.08; mortality: HR = 1.09, 95% CI 1.00-1.19). Similarly, the suggested elevations in incidence and mortality of individual cancer sites (or groups) in the population-based comparison attenuated towards null in the between-sibling comparison. The risk elevations for smoking or alcohol-related cancers in the population-based comparison (incidence: HR = 1.18, 95% CI 1.11–1.24; mortality: HR = 1.20, 95% CI 1.12–1.29) were partially mediated by alcohol-related morbidities during follow-up. Collectively, our findings suggest that the association between stress-related disorders and cancer risk and mortality is largely explained by familial factors, including shared behavioral hazards.

Medical knowledge and information needs among women with pathogenic variants in moderate-risk genes for hereditary breast cancer attending genetic counseling at an academic hospital in Germany-A qualitative approach

With 69,000 newly diagnosed cases every year, breast cancer (BC) is the most frequent cancer disease among women in Germany. Familial clustering is seen in about 30% of newly diagnosed cases. Besides the high-risk genes BRCA1/2, there are also moderate-risk BC genes (MBCG) that are associated with a 20%-50% risk of BC, such as CHEK2, ATM, and PALB2. In Germany, carriers of pathogenic variants in MBCG receive specific information on their test results, individual risks, and preventive options during genetic counseling for the disclosure of the results in a specialized center. Little is known about the medical knowledge that women have after attending counseling. This study aims to identify the medical knowledge, further information needs, and the possible impact of a lack of information on dealing with everyday life for women with pathogenic variants in MBCG who have attended genetic counseling at an academic hospital in Germany. Problem-centered, guided, individual interviews were conducted with twelve women carrying pathogenic variants in MBCG. The interview guide was developed based on the methods of the problem-centered interview according to Witzel. The interview analysis was based on Mayring's qualitative content analysis. The women were between 29 and 59 years old and carried pathogenic variants in the risk genes CHEK2 (n = 8), ATM (n = 1), or PALB2 (n = 3). Several medical uncertainties and information needs emerged from the data, concerning (a) medical terms, (b) risk perception, (c) BC therapy for hereditary BC, (d) lifestyle advice and risk factors, and (e) family planning and risk-reducing mastectomy. Women with pathogenic variants in MBCG might develop their own conceptions regarding the onset of disease and inheritance. In order to meet the need for information and address the uncertainties that may still exist after genetic counseling, structured, evidence-based and comprehensible written information in German should be developed for this group.

The Effects of a Tripod Approach for Cancer Patients on Illness Stress, Health-Promoting Lifestyle, Hope, and Resilience

BACKGROUND

Health-related exercise and education program for cancer patients are necessary to provide physical and emotional support to enable efficient and appropriate self-management at home.

OBJECTIVE

This study aimed to investigate the effects of a tripod approach including physical exercise, education, and emotional support program on illness stress, health promotion lifestyle, hope, and resilience in cancer patients.

INTERVENTIONS/METHODS

This was a quasi-experimental repeated-measures study using a pre-post design with a nonhomogeneous control group. A total of 72 cancer patients (experimental group = 37, control group = 35) who were currently receiving treatment and staying at home were enrolled.

RESULTS

The experimental group showed significantly lower illness stress scores (F = 17.35, P < .001) and increase in health promotion lifestyle scores (F = 4.05, P = .048) compared with the control group, especially social relationships (t = 1.85, P = .073) and stress management (t = 2.30, P = .027). However, there were no effects on hope and resilience. Also, illness stress showed significant changes after 6 weeks (t = -3.35, P = .001) and after 10 weeks (t = -5.04, P < .001). Overall health promotion lifestyle showed changes after 10 weeks (t = 2.25, P = .030), with meaning of life (t = 2.57, P = .014), stress management (t = 2.30, P = .027), and medical behaviors (t = 2.46, P = .019) especially showing significant changes.

CONCLUSIONS

The results showed that the tripod approach had positive effects on illness stress and health promotion lifestyle of cancer patients staying at home. Further study to improve positive emotions such as hope and resilience is needed.

IMPLICATIONS FOR PRACTICE

Based on our findings, combining nursing intervention with physical exercise, education, and emotional support could be incorporated into cancer patients in community and early survivorship care plans in clinical practice.

The Role of Stress in Breast Cancer Incidence: Risk Factors, Interventions, and Directions for the Future

Stress is a common belief among breast cancer patients and the public to explain variation in breast cancer incidence. Epidemiological studies interrogating the relationship between stress and cancer have reported mixed results. The impact of the topic and the lack of consensus has sparked this review of the literature to investigate gaps in knowledge and identify areas of research. We first present a brief summary of the biopsychosocial model generally used to conduct research on stress. We then divide the overview of the literature into areas of research focus. These include the role of distressing life events in breast cancer incidence, the role of adverse childhood events in later breast cancer incidence, the importance of race and socioeconomic status (SES) as social determinants of breast cancer incidence, and the specific role of chronic stress in relation to breast cancer. For each topic, we discuss the potential of stress as a risk factor and possible intervention strategies that could reduce the effects of stress. We then identify further research questions to be probed to fill the gaps in knowledge. We conclude with a discussion of future research directions for stress research as it relates to breast cancer incidence.

Lay Etiology, Self-Efficacy and Patient Activation Among Cancer Patients

BACKGROUND

We aimed at clarifying correlations between lay etiologies, self-efficacy, and patient activation among cancer patients.

METHODS

Patients with different kinds of cancer answered a questionnaire on self-efficacy, lay etiology, and patient activation.

RESULTS

639 patients participated. Psychological reasons/stress (43.3%) and destiny (41.6%) were the most cited causes. Lay etiology was influenced by demographics, self-efficacy, and patient activation. Men, younger people, and active patients more often described internal causes of cancer, women and religious patients more often external causes. Patients with higher scores of self-efficacy were more often convinced of external cancer causes.

CONCLUSION

By identifying individual disease theories, physicians may improve patient-physician communication.

The association between life satisfaction, vitality, self-rated health, and risk of cancer

PURPOSE

Only few prospective studies have been conducted on the contribution of quality of life-related factors to the risk of cancer. The aim of this study was to investigate the prospective associations of three quality of life-related factors with the risk of cancer; life satisfaction, vitality, and self-rated health.

METHODS

In 2009-2011, 7189 participants in the Copenhagen Aging and Midlife Biobank were asked to rate their life satisfaction, their vitality, and their health. The study population was followed until the end of 2015 for registration of cancer in the Danish National Patient Register.

RESULTS

During the follow-up period, cancer was diagnosed in 312 individuals. Life satisfaction was not associated with the risk of cancer. Vitality was significantly associated with the risk of cancer, but the association became non-significant after adjustment for age, sex, socioeconomic position, and lifestyle factors. However, when additionally adjusting for life satisfaction, individuals who rated their vitality as low had a hazard ratio of 1.46 (95% confidence interval [CI] 1.04-2.07) for the development of cancer. Individuals who rated their health as poor had a hazard ratio of 1.70 (95% CI 1.27-2.26) for the development of cancer, compared with individuals with good, very good, or excellent self-rated health. The association remained significant after adjustment for basic confounders, life satisfaction, and vitality.

CONCLUSION

A better grasp of the significance of quality of life-related factors for the risk of cancer may be of great importance to population-based cancer prevention that aims to target early risk factors for development of cancer across widespread cancer sites.

Does stress increase risk of breast cancer? A 15-year prospective study

OBJECTIVE

The possible impact of stress on cancer incidence remains controversial. We prospectively evaluated associations between life event stressors, social support, personality characteristics (optimism, anger control, antiemotionality), and risk of developing primary breast cancer (BCa), in women at increased familial risk of BCa.

METHODS

A prospective cohort, repeated measures design was used. Recruitment was through the Kathleen Cuningham Foundation Consortium for Research into Familial Breast Cancer, which collects genetic, epidemiological, and clinical data from Australasian families with multiple BCa cases. Acute and chronic stressors for the prior 3 years and psychosocial, clinical, and epidemiological variables were measured at cohort entry and at 3-yearly intervals. Cox proportional hazard regression analysis controlling for BCa risk factors and familial clustering was undertaken. The primary outcome was histopathologically confirmed BCa (invasive or ductal carcinoma in situ, including occult cases diagnosed during risk-reducing mastectomy).

RESULTS

Of 3595 consecutive women invited to participate, 3054 (85.0%) consented. Of these, 2739 (89.7%) from 990 families (range 1-16 per family) completed at least 1 assessment point. During the study, 103 women were diagnosed with BCa. No stressor or psychosocial variable or interaction between them was significantly associated with BCa in unadjusted or adjusted models (total acute stressors HR = 1.03 [0.99-1.08], P = .19; total chronic stressors HR = 1.0 [0.90-1.11], P = .98).

CONCLUSIONS

This study did not demonstrate an association between acute and chronic stressors, social support, optimism, antiemotionality or anger control, and BCa risk. Women should focus on proven methods of BCa risk reduction.

Possible role of stress, coping strategies, and life style in the development of breast cancer

Objective The aim of the present study was to investigate the possibility of the effect of life long stressful events, along with coping method used, perception of social support, and life style on the development of breast cancer. Methods In this hospital-based case control study, the study group comprised 250 women with breast cancer who were followed by Florence Nightingale Breast Study Group. Control group included 250 women, who had similar sociodemographic characteristics to the study group. Data were collected with semi-structured interview form, Healthy Life Style Behavior Scale, Coping Strategy Indicator, and Stress Evaluation Form developed by us. Results In multivariate analysis, family history of cancer (OR: 1.55, 95% CI: 2.29-1.05), inadequate social support (OR: 1.83, 95% CI: 1.23-2.73), and loss of father during childhood (OR: 2.68, 95% CI: 5.52-1.30) and serious stressor within the last five years (OR: 4.72, 95% CI: 7.03-3.18) were found to be risk factors increasing the risk of breast cancer. When family history of cancer was excluded from the model, the presence of psychiatric disorder history (OR: 1.95, 95% CI: 3.26-1.17) and major life events (OR: 2.24, 95% CI: 4.07-1.24) were added to the model as risk factors. Conclusion The present study indicates that especially the stressful events experienced within the last five years plays an undeniable role in the risk of breast cancer. Social support may be as important in the period before the diagnosis as in the period after diagnosis.

Causal Attribution of Breast Cancer by Survivors in French West Indies

Patients frequently ask about the cause of their breast cancer. To answer, physicians refer to breast cancer risk factors based on medical reports. We aim to assess these risk factors for the point of view of survivors, a point of view which seems to differ from that of medical references. We ran a survey with open- and closed-ended questionnaires on patients' opinions about risks factors both for women in general and for their own case. We also collected data on their sources of information on this subject. Most patients had no opinion. The most frequently cited risk factors were stress, then genetic causes, and poor diet. Internet was the leading source of information for patients, followed by physicians and magazines. Our study highlights the mismatch between breast cancer risk factors as perceived by scientists and by survivors. Survivors tend to focus on non-controllable risk factors. Taking into account attribution theories of life events, an awareness of patient opinion may be valuable for psychological support of survivors, and it may be informative to record the way in which patients attribute causality for life events such as breast cancer and, more generally, all type of cancer.

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.

Rainbow of KIBOU (ROK) study: a Breast Cancer Survivor Cohort in Japan

Background

Although there are a large number of epidemiological studies investigating the etiological role of lifestyle factors in breast cancer, there are few studies on the association between lifestyle factors and breast cancer prognosis. To investigate the influence of lifestyle factors such as diet and physical activity, use of complementary and alternative medicine, and psychosocial factors on prognosis, we designed a large-scale cohort study of female breast cancer patients in Japan.

Methods

The planned sample size is 7200. The cohort is being conducted in collaboration with several clinical trials, a cancer registry, and daily practice. Information on clinical factors, treatment, and follow-up will be obtained from the clinical trials and participating hospitals. A self-administered questionnaire is given to subjects before, immediately after, or 1 to 5 years after surgery. Blood and tissue samples are also collected. The primary endpoint is disease-free survival. The secondary endpoints are overall survival and health-related quality of life. The follow-up period will be at least 5 years after the last participant is enrolled. Recruitment began in November 2007.

Current status

As of April 2017, there are 5852 patients enrolled in the study along with 1430 biological samples and the study is still ongoing. The number of subjects enrolled in the study is already the largest in the world.

Conclusions

The ROK study will provide much important evidence for breast cancer survivorship.

Lifetime report of perceived stress at work and cancer among men: A case-control study in Montreal, Canada

BACKGROUND

The association between perceived workplace psychological stress, over the entire work career, and cancer among men has never been assessed. This was explored in the context of a population-based case-control study conducted in Montreal, Canada.

METHODS

3103 incident cancer cases (11 types) diagnosed in 1979-1985 and 512 population controls were interviewed. Subjects described in detail each job held during their lifetime, including the occurrence of stress, and its reason. Logistic regression estimated odds ratios (OR) and 95% confidence intervals (CI) for the association between perceived workplace stress and its duration, and each cancer site, adjusting for lifestyle and occupational factors.

RESULTS

Employment in at least one stressful job was associated with increased odds of cancers of the lung (OR=1.33, 95% CI: 1.01-1.75), colon (OR=1.51, 95% CI: 1.15-1.98), bladder (OR=1.37, 95% CI: 1.03-1.81), rectal (OR=1.52, 95% CI: 1.10-2.10), and stomach (OR=1.53, 95% CI: 1.08-2.15). A duration-response trend was found for cancers of the lung, colon, rectum, stomach, and for NHL. Subjects reported changes in stress level over their career. Perceived stress was ascribed to several sources, including high demand and time pressure, financial issues, job insecurity, and hazardous conditions.

CONCLUSION

Prolonged exposure to perceived stress at work was associated with greater odds of cancer at 5 out of 11 sites. While over reporting of stress by cases cannot be fully ruled out, these associations, if substantiated, would bear important public health significance. Prospective studies building on detailed stress assessment protocols considering all sources and changes over the career are necessary.

Biobehavioral approaches to cancer progression and survival: Mechanisms and interventions

Over the last decade, there have been groundbreaking strides in our understanding of the multiple biological pathways by which psychosocial and behavioral factors can affect cancer progression. It is now clear that biobehavioral factors not only affect cellular immunity but both directly and indirectly modulate fundamental processes in cancer growth, including inflammation, angiogenesis, invasion, and metastasis. There is also an emerging understanding of how psychological and behavioral factors used in interventions can impact these physiological processes. This review outlines our current understanding of the physiological mechanisms by which psychological, social, and behavioral processes can affect cancer progression. The intervention literature is discussed, along with recommendations for future research to move the field of biobehavioral oncology forward.

Understanding and effectively addressing breast cancer in African American women: Unpacking the social context

Black women have a higher incidence of breast cancer before the age of 40 years, more severe disease at all ages, and an elevated mortality risk in comparison with white women. There is limited understanding of the contribution of social factors to these patterns. Elucidating the role of the social determinants of health in breast cancer disparities requires greater attention to how risk factors for breast cancer unfold over the lifecourse and to the complex ways in which socioeconomic status and racism shape exposure to psychosocial, physical, chemical, and other individual and community-level assaults that increase the risk of breast cancer. Research that takes seriously the social context in which black women live is also needed to maximize the opportunities to prevent breast cancer in this underserved group. Cancer 2016;122:2138-49. © 2016 American Cancer Society.

Psychological stress, adverse life events and breast cancer incidence: a cohort investigation in 106,000 women in the United Kingdom

Background

Women diagnosed with breast cancer frequently attribute their cancer to psychological stress, but scientific evidence is inconclusive. We investigated whether experienced frequency of stress and adverse life events affect subsequent breast cancer risk.

Methods

Breast cancer incidence was analysed with respect to stress variables collected at enrolment in a prospective cohort study of 106,000 women in the United Kingdom, with 1783 incident breast cancer cases. Relative risks (RR) were obtained as hazard ratios using Cox proportional hazards models.

Results

There was no association of breast cancer risk overall with experienced frequency of stress. Risk was reduced for death of a close relative during the 5 years preceding study entry (RR = 0.87, 95 % confidence interval (CI): 0.78–0.97), but not for death of a spouse/partner or close friend, personal illness/injury, or divorce/separation. There was a positive association of divorce with oestrogen-receptor-negative (RR = 1.54, 95 % CI: 1.01–2.34), but not with oestrogen-receptor-positive breast cancer. Risk was raised in women who were under age 20 at the death of their mother (RR = 1.31, 95 % CI: 1.02–1.67), but not of their father, and the effect was attenuated after excluding mothers with breast or ovarian cancer (RR = 1.17, 95 % CI: 0.85–1.61).

Conclusions

This large prospective study did not show consistent evidence for an association of breast cancer risk with perceived stress levels or adverse life events in the preceding 5 years, or loss of parents during childhood and adolescence.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-016-0733-1) contains supplementary material, which is available to authorized users.

The Risk of Cancer in Patients With Obsessive-Compulsive Disorder: A Nationwide Population-Based Retrospective Cohort Study

Previous studies suggest a link between anxiety disorders and cancer. The aim of the study was to evaluate the risk of cancer among patients with obsessive-compulsive disorder (OCD) using a nationwide population-based dataset. We recruited newly diagnosed OCD patients without antecedent cancer from the Taiwan National Health Insurance Research Database between 2002 and 2011. The standardized incidence ratios (SIRs) were estimated for 22 specific cancer types among OCD patients and we determined the SIRs for subgroups according to age and sex group. In addition, because of a potential detection bias, a subgroup analysis stratified with the duration of the OCD diagnosis was carried out. Among the 52,656 OCD patients, who were followed up for 259,945 person-years (median follow-up = 4.9 years), there were 718 cases of cancer. Patients with OCD did not exhibit an increased overall cancer risk relative to the general population (SIR 1.05, 95% confidence interval [CI] 0.98-1.13). An increased SIR was observed among OCD patients only within the first year of OCD diagnosis (SIR 1.21, 95% CI 1.01-1.43).This study indicated that the overall cancer risk was not elevated among OCD patients. An increased SIR observed among OCD patients within the first year of OCD diagnosis may be caused by a surveillance bias, and because paraneoplastic manifestations presented with obsessive-compulsive behaviors. Prospective study is necessary to confirm these findings.

Exposure to road traffic and railway noise and postmenopausal breast cancer: A cohort study

Exposure to traffic noise may result in stress and sleep disturbances. Studies on self-reported sleep duration and breast cancer risk have found inconsistent results. In a population-based Danish cohort of 29,875 women aged 50-64 years at enrolment in 1993-1997, we identified 1219 incident, postmenopausal breast cancer cases during follow-up through 2010. Mean follow-up time was 12.3 years. Road traffic and railway noise was calculated for all present and historical residential addresses from 1987 to 2010. We used Cox proportional hazard model for analyses and adjusted for hormone replacement therapy use, parity, alcohol consumption and other potential confounders. We found no overall association between residential road traffic or railway noise and breast cancer risk. Among women with estrogen receptor negative breast cancer, a 10-dB higher level of road traffic noise (continuous scale) during the previous 1, 5 and 10 years were associated with 28% (95% CI: 1.04-1.56), 23% (95% CI: 1.00-1.51) and 20% (95% CI: 0.97-1.48) higher risks of estrogen receptor negative breast cancer, respectively, in fully adjusted models. Similarly, a 10-dB increase in railway noise (1-year mean at diagnosis address) increased risk for estrogen receptor negative breast cancer by 38% (95% CI: 1.01-1.89). There was no association between road traffic or railway noise and estrogen receptor positive breast cancer. In conclusion, these results suggest that residential road traffic and railway noise may increase risk of estrogen receptor negative breast cancer. As the first study on traffic noise and breast cancer results should be treated with caution.

The risk of cancer in patients with generalized anxiety disorder: a nationwide population-based study

OBJECTIVE

To evaluate the risk of cancer among patients with generalized anxiety disorder (GAD) in a nationwide population-based dataset.

METHODS

We recruited newly-diagnosed GAD patients aged 20 years or older without antecedent cancer from the Taiwan National Health Insurance Research database between 2000-2010. Standardized incidence ratios (SIRs) of cancers were calculated in GAD patients, and the subgroup of GAD patients diagnosed by psychiatric specialists.

RESULTS

A total of 559 cancers developed among 19,793 GAD patients with a follow-up of 89,485 person-years (median follow-up of 4.34 years), leading to a significantly increased SIR of 1.14 [95% confidence interval (CI) 1.05-1.24]. Male GAD patients had a significantly increased SIR overall (1.30, 95% CI 1.15-1.46) and for lung and prostate cancer (1.77, 95% CI 1.33-2.30 and 2.17, 95% CI 1.56-2.93, respectively). Patients over 80 years of age also had a significantly increased SIR (1.56, 95% CI 1.25-1.92), especially in males. However, psychiatrist-diagnosed GAD patients did not show increased cancer risk relative to the general population, perhaps due to having fewer physical comorbidities than non-psychiatrist-diagnosed GAD patients.

CONCLUSION

This study found that overall cancer risk is elevated among patients with GAD. The risk of lung and prostate cancer also increased in male patients with GAD. This increased cancer risk may be due to physical comorbidities and surveillance bias. Further prospective study is necessary to confirm these findings.

Systems Modeling in Integrative Oncology

Systems modeling provides an integrated framework to capture and analyze diverse and multidisciplinary data in a standardized manner. The authors present the Integrative Oncology Systems Model (IOSM) to help assess the impact of behavior modification and various therapeutic interventions on cancer development and progression and the resultant effect on survival and quality of life outcomes.

Stress and breast cancer: from epidemiology to molecular biology

Stress exposure has been proposed to contribute to the etiology of breast cancer. However, the validity of this assertion and the possible mechanisms involved are not well established. Epidemiologic studies differ in their assessment of the relative contribution of stress to breast cancer risk, while physiological studies propose a clear connection but lack the knowledge of intracellular pathways involved. The present review aims to consolidate the findings from different fields of research (including epidemiology, physiology, and molecular biology) in order to present a comprehensive picture of what we know to date about the role of stress in breast cancer development.

Breast cancer survivors' beliefs about the causes of breast cancer

OBJECTIVE

To explore the beliefs held by breast cancer (BC) survivors about the factors that contribute to the development of their BC.  

METHODS

The BUPA Health Foundation Health and Well-being after Breast Cancer Study is a prospective cohort study of 1684 women recruited within 12 months of their first diagnosis with invasive BC. Participants completed an enrollment questionnaire (EQ), first follow-up questionnaire (FQ1) and a second follow-up questionnaire (FQ2), 12 months and 24 months post-EQ, respectively. In the FQ2, women were asked whether they believed anything contributed to the development of their BC and whether they had made lifestyle changes since the FQ1. Well-being was assessed at the FQ2 using the psychological general well-being index (PGWB).  

RESULTS

In total, 1496/1684 women completed the FQ2 and 43.5% reported belief in a factor that may have contributed to their developing BC. These women were more likely to be younger (p<0.0001) and educated beyond high school (p<0.0001). Stress (58.1%) was the most common reason given, followed by previous use of hormone therapy (17.0%) and a family history of any cancer (9.8%). Women who believed stress contributed to their BC had lower PGWB scores than other study participants (70.9 ± 16.1, n = 361 versus 77.3 ± 14.9, n = 1071, mean difference = 6.4, 95% CI: 4.6-8.2 p<0.0001) and were more likely to have made lifestyle changes since their BC diagnosis.  

CONCLUSIONS

Many women with BC believe that stress has contributed to their condition. Women who held this belief were more likely to adopt strategies to reduce stress than those who did not.

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.

Discovery of pathway biomarkers from coupled proteomics and systems biology methods

Background

Breast cancer is worldwide the second most common type of cancer after lung cancer. Plasma proteome profiling may have a higher chance to identify protein changes between plasma samples such as normal and breast cancer tissues. Breast cancer cell lines have long been used by researches as model system for identifying protein biomarkers. A comparison of the set of proteins which change in plasma with previously published findings from proteomic analysis of human breast cancer cell lines may identify with a higher confidence a subset of candidate protein biomarker.

Results

In this study, we analyzed a liquid chromatography (LC) coupled tandem mass spectrometry (MS/MS) proteomics dataset from plasma samples of 40 healthy women and 40 women diagnosed with breast cancer. Using a two-sample t-statistics and permutation procedure, we identified 254 statistically significant, differentially expressed proteins, among which 208 are over-expressed and 46 are under-expressed in breast cancer plasma. We validated this result against previously published proteomic results of human breast cancer cell lines and signaling pathways to derive 25 candidate protein biomarkers in a panel. Using the pathway analysis, we observed that the 25 “activated” plasma proteins were present in several cancer pathways, including ‘Complement and coagulation cascades’, ‘Regulation of actin cytoskeleton’, and ‘Focal adhesion’, and match well with previously reported studies. Additional gene ontology analysis of the 25 proteins also showed that cellular metabolic process and response to external stimulus (especially proteolysis and acute inflammatory response) were enriched functional annotations of the proteins identified in the breast cancer plasma samples. By cross-validation using two additional proteomics studies, we obtained 86% and 83% similarities in pathway-protein matrix between the first study and the two testing studies, which is much better than the similarity we measured with proteins.

Conclusions

We presented a ‘systems biology’ method to identify, characterize, analyze and validate panel biomarkers in breast cancer proteomics data, which includes 1) t statistics and permutation process, 2) network, pathway and function annotation analysis, and 3) cross-validation of multiple studies. Our results showed that the systems biology approach is essential to the understanding molecular mechanisms of panel protein biomarkers.

Work and family stress is associated with menstrual disorders but not with fibrocystic changes: cross-sectional findings in Chinese working women

OBJECTIVES

To explore the separate and combined effects of work and family stress on menstrual disorders and fibrocystic changes in Chinese working women.

METHODS

Data were obtained from a cross-sectional study of 1,642 female railway workers. The Effort-Reward Imbalance Questionnaire and Family Stress Scale were used to measure work stress and family stress, respectively; the menstrual and breast conditions were evaluated by gynecologic interview and a medical examination. Multivariate log-binomial regression was performed to analyze the associations.

RESULTS

Menstrual disorders were found in 59.3% of female workers, and 54.8% had fibrocystic changes. The risk of menstrual disorders was significantly elevated with respect to work and family stress. The highest risk was found in the group with combined exposure to both work and family stress (RR with 95% CI 1.33 (1.18-1.49)). No significant association between stress and fibrocystic changes was observed.

CONCLUSIONS

Menstrual disorders were associated with stress from work and family life, but not fibrocystic changes, in working women. Tailored intervention measures reducing the burden of stressful psychosocial work and family environment are needed to improve women's reproductive well-being.

Positive psychology in cancer care: bad science, exaggerated claims, and unproven medicine

Background

Claims of positive psychology about people with cancer enjoy great popularity because they seem to offer scientific confirmation of strongly held cultural beliefs and values.

Purpose

Our goal is to examine critically four widely accepted claims in the positive psychology literature regarding adaptational outcomes among individuals living with cancer.

Methods

We examine: (1) the role of positive factors, such as a “fighting spirit” in extending the life of persons with cancer; (2) effects of interventions cultivating positive psychological states on immune functioning and cancer progression and mortality; and evidence concerning (3) benefit finding and (4) post-traumatic growth following serious illness such as cancer and other highly threatening experiences.

Results

Claims about these areas of research routinely made in the positive psychology literature do not fit with available evidence. We note in particular the incoherence of claims about the adaptational value of benefit finding and post-traumatic growth among cancer patients, and the implausibility of claims that interventions that enhance benefit finding improve the prognosis of cancer patients by strengthening the immune system.

Conclusion

We urge positive psychologists to rededicate themselves to a positive psychology based on scientific evidence rather than wishful thinking.

Low-dose environmental radiation, DNA damage, and cancer: the possible contribution of psychological factors

Radiation causes DNA damage, increases risk of cancer, and is associated with psychological stress responses. This article proposes an evidence-based integrative model in which psychological factors could interact with radiation by either augmenting or moderating the adverse effects of radiation on DNA integrity and eventual tumorigenesis. Based on a review of the literature, we demonstrate the following: (1) the effects of low-dose radiation exposures on DNA integrity and on tumorigenesis; (2) the effects of low-dose radiation exposure on psychological distress; (3) the relationship between psychological factors and DNA damage; and (4) the possibility that psychological stress augments and that psychological resource variables moderate radiation-induced DNA damage and risk of cancer. The additional contribution of psychological processes to radiation-DNA damage-cancer relationships needs further study, and if verified, has clinical implications.

Induction of epigenetic alterations by dietary and other environmental factors

Dietary and other environmental factors induce epigenetic alterations which may have important consequences for cancer development. This chapter summarizes current knowledge of the impact of dietary, lifestyle, and environmental determinants of cancer risk and proposes that effects of these exposures might be mediated, at least in part, via epigenetic mechanisms. Evidence is presented to support the hypothesis that all recognized epigenetic marks (including DNA methylation, histone modification, and microRNA (miRNA) expression) are influenced by environmental exposures, including diet, tobacco, alcohol, physical activity, stress, environmental carcinogens, genetic factors, and infectious agents which play important roles in the etiology of cancer. Some of these epigenetic modifications change the expression of tumor suppressor genes and oncogenes and, therefore, may be causal for tumorigenesis. Further work is required to understand the mechanisms through which specific environmental factors produce epigenetic changes and to identify those changes which are likely to be causal in the pathogenesis of cancer and those which are secondary, or bystander, effects. Given the plasticity of epigenetic marks in response to cancer-related exposures, such epigenetic marks are attractive candidates for the development of surrogate endpoints which could be used in dietary or lifestyle intervention studies for cancer prevention. Future research should focus on identifying epigenetic marks which are (i) validated as biomarkers for the cancer under study; (ii) readily measured in easily accessible tissues, for example, blood, buccal cells, or stool; and (iii) altered in response to dietary or lifestyle interventions for which there is convincing evidence for a relationship with cancer risk.

Cortisol, estrogens and risk of ischaemic heart disease, cancer and all-cause mortality in postmenopausal women: a prospective cohort study

BACKGROUND

Chronic stress may affect morbidity and mortality through neuroendocrine changes, and the ratio of cortisol to sex steroid hormones has been suggested as a biomarker of stress. We aim to address a relation between the ratio of cortisol to estrogens (C/E) and risk of ischaemic heart disease (IHD), hormone-dependent cancers and all-cause mortality among postmenopausal women.

METHODS

Estradiol and cortisol were measured in a subset of 838 women randomly drawn from the second wave of the Copenhagen City Heart Study (n = 5297 examined in 1981-83) as well as among all women who developed hormone-dependent cancers after baseline. The participants were followed in nationwide registers until 2007, with < 0.1% loss to follow-up.

RESULTS

The C/E ratio was not associated with self-reported stress, and there were no clear associations with IHD (highest vs lowest quartile: HR = 1.23; 95% confidence interval 0.83-1.81), hormone-dependent cancers (0.69; 0.45-1.08) or all-cause mortality (1.10; 0.86-1.41).

CONCLUSIONS

The C/E ratio was not associated with morbidity and mortality in women, and we cannot replicate the robust findings of a relation between the cortisol to testosterone ratio and IHD previously reported in men. Whether the C/E ratio is a reasonable biomarker of stress is debatable.

Depression, cortisol, and suppressed cell-mediated immunity in metastatic breast cancer

Cancer treatment is known to have significant immuno-suppressive/dysregulatory effects. Psychological distress and depression, which often accompany cancer diagnosis and treatment, can also suppress or dysregulate endocrine and immune function. Cell-mediated immunity (CMI) is critical for protection against a host of pathogens to which cancer patients may be particularly susceptible. CMI is also important for defense against some tumors. This study explored relationships among depressive symptoms, cortisol secretion, and CMI responses in 72 women with metastatic breast cancer. Depressive symptoms were assessed with the Center for Epidemiologic Studies-Depression Scale (CES-D). Saliva was sampled throughout the day over a 3-day period to obtain a physiologic index of diurnal cortisol concentrations and rhythmicity, which is associated with breast cancer survival time. CMI for specific antigens was measured following intradermal administration of seven commonly encountered antigens (tuberculin, tetanus, diphtheria, Streptococcus, Candida, Trichophyton, and Proteus). Analyses adjusting for relevant medical and treatment variables indicated that women reporting more depressive symptoms showed suppressed immunity as measured by lower average induration size. Women with higher mean diurnal cortisol concentrations also showed suppressed immunity as indicated by a decreased number of antigens to which positive reactions were measured. This study highlights the relationships among depression, stress, and immune function in the context of advanced breast cancer.

Review article: do exercise and fitness protect against stress-induced health complaints? A review of the literature

BACKGROUND

Understanding how exercise influences health is important in designing public health interventions. At present, evidence suggests that there is a positive relationship between exercise and health. However, whether this relationship is partly due to the stress-moderating impact of exercise has been less frequently investigated although more and more people are taxed by stressful life circumstances.

METHODS

A comprehensive review of studies testing the potential of exercise as a stress-buffer was conducted (including literature from 1982 to 2008). The findings are based on a narrative review method. Specific criteria were taken into account to evaluate causality of the evidence.

RESULTS

About half of the studies reported at least partly supportive results in the sense that people with high exercise levels exhibit less health problems when they encounter stress. The causality analyses show that stress-moderation effects were consistently found in different samples and with different methodological approaches. Although more support results from cross-sectional studies, exercise-based stress-buffer effects were also found in prospective, longitudinal and quasi-experimental investigations.

CONCLUSIONS

This review underscores the relevance of exercise as a public health resource. Recommendations are provided for future research. More prospective and experimental studies are needed to provide insight into how much exercise is necessary to trigger stress-buffer effects. Furthermore, more information is warranted to conclude which sort of exercise has the strongest impact on the stress-illness-relationship.

Mitochondrial copy number and risk of breast cancer: a pilot study

It has been proposed that the copy number of mitochondria DNA (mtDNA) per cell reflects gene-environment interactions between unknown hereditary factors and exposures affecting levels of oxidative stress. However, whether copy number of mtDNA could be a risk predictor of oxidative stress-related human cancers, such as breast cancer, remains to be determined. To explore the role of mtDNA copy number in breast cancer etiology, we analyzed mtDNA copy number in whole blood from 103 patients with breast cancer and 103 matched control subjects and examined in relation to endogenous antioxidants. Case patients with breast cancer had a statistically significantly higher mtDNA copy number than control subjects (median: 1.29 vs. 0.80, P<0.01). High mtDNA copy number (above the median in controls) was associated with a statistically significantly increased risk of breast cancer, compared with low copy number (Odds ratio (OR)=4.67, 95% CI: 2.45-8.92), with a statistically significant dose-response relationship in trend analysis (P<0.01). Moreover, mtDNA copy number was significantly inversely associated with several important endogenous oxidants and antioxidants in blood in either the cases (total glutathione, CuZn-SOD activity and myeloperoxidase (MPO)) or the controls (catalase (CAT) activity). These results suggest the mtDNA copy number could be associated with risk of breast cancer, perhaps through an oxidative stress mechanism.

Public awareness of gastric cancer risk factors and disease screening in a high risk region: a population-based study

PURPOSE

This study involved a population-based survey to provide evidence of public awareness of risk factors of gastric cancer and to investigate attitudes for the screening of gastric cancer in the South Korean population.

MATERIALS AND METHODS

Using a nationwide random selection method, 2014 subjects were enrolled in the study between 5 September 2006 and 25 September 2006.

RESULTS

In terms of the awareness of risk factors, awareness was scored as the percentage of the probability of developing gastric cancer when a subject had a particular risk factor. For the risk factors, stress ranked highest with a score of 73.5%, followed by chronic gastritis (score of 72.1%), gastric ulcer (score of 71.2%) and a previous gastrectomy history (score of 68.7%). Other factors included a diet of charred foods (score of 67.3%), alcohol use (score of 65.3%), salty diet (score of 65.1%), history of smoking (score of 64.3%) and Helicobacter pylori infection (score of 57.5%). Subjects believed that 60.4% of all gastric cancers were preventable by lifestyle modification and the subjects believed that regular screening could prevent 72.1% of all gastric cancers. However, 54% of subjects did not receive regular screening and the most common reason for not undergoing screening was a lack of symptoms.

CONCLUSION

Public education about the risk factors of gastric cancer and of lifestyle modifications and the importance of regular screening regardless of the presence of symptoms should be emphasized to reduce gastric cancer mortality in South Korea.

Influence of stressors on breast cancer incidence in the Women's Health Initiative

OBJECTIVE

To examine associations among life events stress, social support, and breast cancer incidence in a cohort of postmenopausal women. DESIGN AND MAIN OUTCOME MEASURE: Women's Health Initiative observational study participants, breast cancer free at entry, who provided assessment of stressful life events, social support, and breast cancer risk factors, were prospectively followed for breast cancer incidence (n = 84,334).

RESULTS

During an average of 7.6 years of follow-up, 2,481 invasive breast cancers were diagnosed. In age-adjusted proportional hazards models, 1 stressful life event was associated with increased risk, but risk decreased with each additional stressful life event. After adjustment for confounders the decreasing risk was not significant. Stressful life events and social support appeared to interact in relation to breast cancer risk such that women who had greater number of stressful life events and low social support had a decreased risk of breast cancer.

CONCLUSIONS

This study found no independent association between stressful life events and breast cancer risk. The results are compatible with a more complex model of psychosocial factors interacting in relation to breast cancer risk.

[Should psychological events be considered cancer risk factors?]

BACKGROUND

The possibility that life events, personality or depression can be considered risk factors for cancer has been of great interest among the lay public and doctors.

METHODS

A critical review of different publications of meta-analyses, case-control studies and cohort studies investigating a possible relation between the onset of cancer and life events, personality disorders or depression is presented. Many studies have methodological limitations with possible bias, which may explain controversial results. We selected 32 studies from which conclusions can be drawn with the least amount of bias.

RESULTS

Eighteen out of 32 publications whose methodology permits unbiased interpretation show no link between psychological factors and the risk of cancer. Six publications show a significant link only in one or several subgroups and four surveys, three of which were published by the same author, show an inverse relation in gynecological cancers. As for life events and breast cancer, the results are slightly in favor of a positive relation in four studies; four others showed no relation and one argues in favor of an inverse risk, which means a protective effect for this cancer. For life events and other cancers, studies show no relation, with the possible exception of cancers in women where endogenous estrogens can play a role (colon and endometrial cancers), where there is an inverse relation. No studies showed a significant relation between personality features and the risk of cancer. The studies of a possible relation between depression and cancer are controversial and no conclusion can be drawn.

CONCLUSION

It cannot be confidently concluded that life events, personality features or depression play a role in the onset of cancer.

Diagnosis-specific sickness absence as a predictor of mortality: the Whitehall II prospective cohort study

OBJECTIVE

To investigate whether knowing the diagnosis for sickness absence improves prediction of mortality.

DESIGN

Prospective cohort study established in 1985-8. Sickness absence records including diagnoses were obtained from computerised registers.

SETTING

20 civil service departments in London.

PARTICIPANTS

6478 civil servants aged 35-55 years.

MAIN OUTCOME MEASURES

All cause, cardiovascular, and cancer mortality until 2004, average follow-up 13 years.

RESULTS

After adjustment for age, sex, and employment grade, employees who had one or more medically certified spells of sickness absence (>7 days) in a three year period had a mortality 1.7 (95% CI 1.3 to 2.1) times greater than those with no medically certified spells. Inclusion of diagnoses improved the prediction of all cause mortality (P=0.03). The hazard ratio for mortality was 4.7 (2.6 to 8.5) for absences with circulatory disease diagnoses, 2.2 (1.4 to 3.3) for surgical operations, and 1.9 (1.2 to 3.1) for psychiatric diagnoses. Psychiatric absences were also predictive of cancer mortality (2.5 (1.3 to 4.7)). Associations of infectious, respiratory, and injury absences with overall mortality were less marked (hazard ratios from 1.5 to 1.7), and there was no association between musculoskeletal absences and mortality.

CONCLUSIONS

Major diagnoses for medically certified absences were associated with increased mortality, with the exception of musculoskeletal disease. Data on sickness absence diagnoses may provide useful information to identify groups with increased health risk and a need for targeted interventions.

Psychosocial factors, biological mediators, and cancer prognosis: a new look at an old story

PURPOSE OF REVIEW

The present article briefly reviews the prognostic role of psychosocial factors in cancer and concentrates on biological markers that may mediate such relationships. We focus on specific markers that show promising mediating roles.

RECENT FINDINGS

The article reviews the prognostic role of psychosocial factors as shown in longitudinal studies and in previous reviews. We present the general stress response and its relevance to cancer progression. The main focus of the article is on the prognostic roles of specific biomarkers that had to meet three criteria for being accepted as biomarkers - being related to a psychosocial factor at the level of the brain, the circulation, and the tissue/cellular level. We review studies supporting the mediating roles of neurohormones and neurotransmitters (e.g., cortisol, norepinephrine), the vagal nerve and inflammation, interleukin-1, DNA damage, and the hormone oxytocin.

SUMMARY

These biomarkers may mediate the relationships between certain psychosocial factors (e.g., hopelessness, social support) and cancer progression. Future studies should test the effects of altering such biomarkers on the prognosis of patients scoring high/low on their associated psychosocial factors. Clinical implications that need to be tested are provided.

Do stress-related psychosocial factors contribute to cancer incidence and survival?

A substantial body of research has investigated the associations between stress-related psychosocial factors and cancer outcomes. Previous narrative reviews have been inconclusive. In this Review, we evaluated longitudinal associations between stress and cancer using meta-analytic methods. The results of 165 studies indicate that stress-related psychosocial factors are associated with higher cancer incidence in initially healthy populations (P = 0.005); in addition, poorer survival in patients with diagnosed cancer was noted in 330 studies (P <0.001), and higher cancer mortality was seen in 53 studies (P <0.001). Subgroup meta-analyses demonstrate that stressful life experiences are related to poorer cancer survival and higher mortality but not to an increased incidence. Stress-prone personality or unfavorable coping styles and negative emotional responses or poor quality of life were related to higher cancer incidence, poorer cancer survival and higher cancer mortality. Site-specific analyses indicate that psychosocial factors are associated with a higher incidence of lung cancer and poorer survival in patients with breast, lung, head and neck, hepatobiliary, and lymphoid or hematopoietic cancers. These analyses suggest that stress-related psychosocial factors have an adverse effect on cancer incidence and survival, although there is evidence of publication bias and results should be interpreted with caution.

Personality factors and breast cancer risk: a 13-year follow-up

Consistent scientific evidence on the possible relationship between psychologic variables and breast cancer development is lacking. In 1996, our group first reported on the present prospective, longitudinal study. We found a weak association between a high score on the antiemotionality scale (indicating an absence of emotional behavior or a lack of trust in one's own feelings) and the development of breast cancer. No associations were found between any of the other 10 studied personality traits and breast cancer development. However, the study had a relatively short follow-up and did not investigate interaction effects between various personality traits. Therefore, the current follow-up study was conducted with the same cohort, which included the 9705 women who attended a biennial population surveillance program for breast cancer and completed a self-report personality questionnaire between January 1, 1989, and December 31, 1990. Women who developed breast cancer during the period from May 17, 1995, through January 1, 2003, formed the case group (n = 217) and were compared with age-matched women without breast cancer who formed the control group (n = 868) with regard to personality traits and medical risk factors for breast cancer. None of the personality factors were statistically significantly associated with an increased risk of breast cancer, with or without adjusting for the medical risk factors. Also, the occurrence of a combination of various personality traits (eg, a so-called cancer-prone personality) was not related to breast cancer development.