Associations between selected life events and cancer

Neighborhood disadvantage and individual-level life stressors in relation to breast cancer incidence in US Black women

BACKGROUND

Research on psychosocial stress and risk of breast cancer has produced conflicting results. Few studies have assessed this relation by breast cancer subtype or specifically among Black women, who experience unique chronic stressors.

METHODS

We used prospective data from the Black Women's Health Study, an ongoing cohort study of 59,000 US Black women, to assess neighborhood- and individual-level psychosocial factors in relation to risk of breast cancer. We used factor analysis to derive two neighborhood score variables after linking participant addresses to US Census data (2000 and 2010) on education, employment, income and poverty, female-headed households, and Black race for all households in each residential block group. We used Cox proportional hazards regression to estimate hazard ratios (HR) and 95% confidence intervals (CI) adjusted for established breast cancer risk factors.

RESULTS

During follow-up from 1995 to 2017, there were 2167 incident invasive breast cancer cases (1259 estrogen receptor positive (ER +); 687 ER negative (ER-)). For ER- breast cancer, HRs were 1.26 (95% CI 1.00-1.58) for women living in the highest quartile of neighborhood disadvantage relative to women in the lowest quartile, and 1.24 (95% CI 0.98-1.57) for lowest versus highest quartile of neighborhood socioeconomic status (SES). For ER+ breast cancer, living in the lowest quartile of neighborhood SES was associated with a reduced risk of ER+ breast cancer (HR = 0.83, 95% CI 0.70-0.98). With respect to individual-level factors, childhood sexual abuse (sexual assault ≥ 4 times vs. no abuse: HR = 1.35, 95% CI 1.01-1.79) and marital status (married/living together vs. single: HR = 1.29, 95% CI 1.08-1.53) were associated with higher risk of ER+, but not ER- breast cancer.

CONCLUSION

Neighborhood disadvantage and lower neighborhood SES were associated with an approximately 25% increased risk of ER- breast cancer in this large cohort of Black women, even after control for multiple behaviors and lifestyle factors. Further research is need to understand the underlying reasons for these associations. Possible contributing factors are biologic responses to the chronic stress/distress experienced by individuals who reside in neighborhoods characterized by high levels of noise, crime and unemployment or the direct effects of environmental toxins.

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.

Does childhood misfortune increase cancer risk in adulthood?

OBJECTIVE

To address the inconsistent findings on whether childhood misfortune increases adult cancer occurrence.

METHODS

This study uses longitudinal data from the National Survey of Midlife Development in the United States (MIDUS) that first sampled 3,032 respondents aged 25 to 74 during 1995-1996. A series of logistic regressions were estimated separately for men and women to test whether the effect of childhood misfortune on adult cancer was largely cumulative or specific to the type or profile of misfortune.

RESULTS

For men, additive childhood misfortune, physical abuse by father, and frequent abuse by either parent increased cancer risk. For women, physical abuse by mother and frequent abuse by either parent increased cancer risk.

DISCUSSION

Analyses revealed the importance of examining alternative specifications of childhood misfortune for men and women. Additive childhood misfortune predicted cancer for men only, whereas child abuse by parent of the same sex predicted cancer for men and women.

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.

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.

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.

Interactive effects of psychosocial stressors and gender on mouse mammary tumor growth

We have previously demonstrated that social housing condition significantly affects the growth rate of the androgen-responsive Shionogi mouse mammary carcinoma (AR SC115) in male mice. The present study examined the effects of social housing condition and acute daily exposure to a novel environment on the growth rate of an androgen-independent variant of the AR SC115 carcinoma, designated SC115V, in male and female mice. Immediately following tumor cell injection, male and female mice that were reared as individuals (I) or in groups (G) of the same sex were rehoused either from individual to same-sex groups (IG) or from group to individual (GI), or remained in their group housing condition (GG). Approximately half the mice in each housing condition were subjected to acute daily exposure to novel environments (novelty stress), a treatment shown previously to increase the significant difference in tumor growth rates between male mice in the IG and GI housing conditions. The remaining mice were left undisturbed (no novelty stress). In the presence of acute daily novelty stress, the growth rate of the SC115V tumor was significantly increased in GI compared to IG males. However, no significant differences in SC115V tumor growth rates among nonstressed GI, IG, or GG males were observed. For females, in contrast to males, acute daily novelty stress significantly decreased tumor growth in GI compared to IG mice, whereas under nonstressed conditions, tumor growth rate was significantly increased in GI compared to IG females. Neither housing condition nor novelty stress altered estrous cyclicity, nor did the stage of the estrous cycle at the time of tumor cell injection influence tumor growth rates. These findings suggest that social housing condition and novelty stress may interact to produce differential effects on the growth rate of the SC115V tumor in male and female mice.

Death of a husband or marital divorce related to risk of breast cancer in middle-aged women. A nested case-control study among Norwegian women born 1935-1954

A topic of general interest is whether important life changes may play a role in the onset of cancer. The hypothesis of this study was that death of a husband or marital divorce, is associated with an increased risk of breast cancer. The study included 4491 incident breast cancer cases and 44,910 controls, matched on age, in a population-based nested case-control study, among Norwegian women born between 1935 and 1954. The risk of breast cancer among widowed compared to married women showed an odds ratio (OR) of 1.13 [95% confidence interval (CI) 0.94-1.36], after adjusting for age at first birth and parity. For divorced women the analogous OR was 0.83 (95% CI 0.75-0.92), after adjusting for age at first birth, parity and place of residence. Thus, the results did not show any clear evidence that death of a husband or marital divorce was associated with an increased risk of breast cancer.

Psychosocial factors in breast cancer and their possible impact upon prognosis

Breast cancer is the most common cancer form in women. Numerous biological factors have now been identified and accepted as important risk factors and prognosticators. Psychosocial factors are also considered to be of probable importance. A review of the literature studying these factors reveals major methodological problems in evaluating data: small sample size, retrospective design, lack of cross-referencing for other important factors, cross-sectional studies instead of longitudinal studies, and insufficient statistical analysis. Regarding psychosocial factors, some of the most valid studies indicate that the risk of getting breast cancer may be connected with difficulties in expressing feelings, especially ones of aggression; while coping strategy, amount of stress, and level of activity, seem to be of possible influence to the prognosis. A possible connection between psyche and the immunological system has been proposed, but there has been little data so far. Although a series of studies have shown some influence of psychosocial factors on breast cancer, the methodological problems are so large as to leave open the question whether psychosocial factors have any impact upon the disease.