Influence of physical activity and exercise on innate immunity

Breast Cancer-Epidemiology, Risk Factors, Classification, Prognostic Markers, and Current Treatment Strategies-An Updated Review

Simple Summary

Breast cancer is the most common cancer among women. It is estimated that 2.3 million new cases of BC are diagnosed globally each year. Based on mRNA gene expression levels, BC can be divided into molecular subtypes that provide insights into new treatment strategies and patient stratifications that impact the management of BC patients. This review addresses the overview on the BC epidemiology, risk factors, classification with an emphasis on molecular types, prognostic biomarkers, as well as possible treatment modalities.

Abstract

Breast cancer (BC) is the most frequently diagnosed cancer in women worldwide with more than 2 million new cases in 2020. Its incidence and death rates have increased over the last three decades due to the change in risk factor profiles, better cancer registration, and cancer detection. The number of risk factors of BC is significant and includes both the modifiable factors and non-modifiable factors. Currently, about 80% of patients with BC are individuals aged >50. Survival depends on both stage and molecular subtype. Invasive BCs comprise wide spectrum tumors that show a variation concerning their clinical presentation, behavior, and morphology. Based on mRNA gene expression levels, BC can be divided into molecular subtypes (Luminal A, Luminal B, HER2-enriched, and basal-like). The molecular subtypes provide insights into new treatment strategies and patient stratifications that impact the management of BC patients. The eighth edition of TNM classification outlines a new staging system for BC that, in addition to anatomical features, acknowledges biological factors. Treatment of breast cancer is complex and involves a combination of different modalities including surgery, radiotherapy, chemotherapy, hormonal therapy, or biological therapies delivered in diverse sequences.

Does physical activity reduce the risk of prostate cancer? A systematic review and meta-analysis

CONTEXT

Numerous observational epidemiologic studies have evaluated the association between physical activity and prostate cancer (PCa); however, the existing results are inconsistent.

OBJECTIVE

To determine the association between physical activity and risk of PCa.

EVIDENCE ACQUISITION

A systematic search was performed using the Medline, Embase, and Web of Science databases through 15 May 2011 to identify all English-language articles that examined the effect of physical activity on the risk of PCa. This meta-analysis was conducted according to the guidelines for the meta-analysis of observational studies in epidemiology.

EVIDENCE SYNTHESIS

This meta-analysis consisted of 88,294 cases from 19 eligible cohort studies and 24 eligible case-control studies. When data from both types of studies were combined, total physical activity (TPA) was significantly associated with a decreased risk of PCa (pooled relative risk [RR]: 0.90; 95% confidence interval [CI], 0.84-0.95). The pooled RR for occupational physical activity (OPA) and recreational physical activity (RPA) were 0.81 (95% CI, 0.73-0.91) and 0.95 (95% CI, 0.89-1.00), respectively. Notably, for TPA, we observed a significant PCa risk reduction for individuals between 20 and 45 yr of age (RR: 0.93; 95% CI, 0.89-0.97) and between 45 and 65 yr of age (RR: 0.91; 95% CI, 0.86-0.97) who performed activities but not for individuals <20 yr of age or >65 yr of age.

CONCLUSIONS

There appears to be an inverse association between physical activity and PCa risk, albeit a small one. Given that increasing physical activity has numerous other health benefits, men should be encouraged to increase their physical activity in both occupational and recreational time to improve their overall health and potentially decrease their risk of PCa.

Physical activity and hematologic cancer prevention

This chapter presents the epidemiologic evidence on the association between physical activity and hematologic cancers and related hypothesized biologic mechanisms. Some preliminary indications of a protective role for physical activity for non-Hodgkin's lymphoma, leukemia, multiple myeloma, and Hodgkin's lymphoma exist, but the level of epidemiologic evidence is still insufficient to make any definitive conclusions regarding the nature of these associations. Several plausible biologic mechanisms underlying the possible associations between physical activity and hematologic cancers have been proposed, including enhancement of immune function, reduction in obesity, improvement of antioxidant defense systems, impact on metabolic hormones, and anti-inflammatory effects. Future studies should improve the estimation of physical activity by using more reliable, valid, and comprehensive measurement tools, assessing all components of physical activity (type, intensity, and time period), and conducting intervention studies to evaluate the effect of physical activity on various biomarkers of cancer in order to provide further insight into plausible biologic mechanisms underlying the possible association between physical activity and hematologic cancers.

Mecanismos adaptativos do sistema imunológico em resposta ao treinamento físico

O treinamento físico, de intensidade moderada, melhora os sistemas de defesa, enquanto que o treinamento intenso causa imunossupressão. Os mecanismos subjacentes estão associados à comunicação entre os sistemas nervoso, endócrino e imunológico, sugerindo vias autonômicas e modulação da resposta imune. Células do sistema imune, quando expostas a pequenas cargas de estresse, desenvolvem mecanismo de tolerância. Em muitos tecidos tem-se demonstrado que a resposta a situações agressivas parece ser atenuada pelo treinamento físico aplicado previamente, isto é, o treinamento induz tolerância para situações agressivas/estressantes. Nesta revisão são relatados estudos sugerindo os mecanismos adaptativos do sistema imunológico em resposta ao treinamento físico.

Physical activity, obesity, energy intake, and the risk of non-Hodgkin's lymphoma: a population-based case-control study

The authors conducted a population-based case-control study of 1,030 cases with histologically confirmed, incident non-Hodgkin's lymphoma (NHL) and 3,106 controls to assess the impact of recreational physical activity, obesity, and energy intake on NHL risk in Canada from 1994 to 1997. Compared with those for subjects in the lowest quartiles of total recreational physical activity, multivariable-adjusted odds ratios for subjects in the highest quartile were 0.79 (95% confidence interval (CI): 0.59, 1.05) for men and 0.59 (95% CI: 0.42, 0.81) for women. Obesity (body mass index > or = 30 kg/m2) was associated with odds ratios of 1.59 (95% CI: 1.18, 2.12) for men and 1.36 (95% CI: 1.00, 1.84) for women. For men and women with a lifetime maximum body mass index of > or = 30 kg/m2, respective odds ratios were 1.55 (95% CI: 1.16, 2.06) and 1.10 (95% CI: 0.83, 1.46). For men and women in the highest quartiles of calorie intake, respective odds ratios were 1.95 (95% CI: 1.45, 2.62) and 1.13 (95% CI: 0.84, 1.52). Some differences were found between histologic subtypes of NHL for these associations. This study suggests that recreational physical activity decreases NHL risk, while obesity and excess calorie intake increase it. More studies are needed to confirm these results, especially the differences between histologic subtypes.

Natural killer cells and exercise training in the elderly: a review

Consistent reports of the positive relationship between regular physical activity and immunosenescence have generated much excitement in the field of exercise immunology. It is generally accepted that natural killer (NK) cell activity per NK cell decreases with age; decreases in NKCA have been associated with infection and death in the aged. The effects of exercise and training on natural killer cells, components of the innate immune system, have been studied extensively in young people. However, the published research on the elderly population is limited. Generally it has been found that training increases or does not change natural killer cell activity or counts in the elderly. The clinical relevance of these results is yet to be fully explored. In addition, the limitations of these studies on immune function have been many, and studies are often difficult to compare due to differences in their methods and presentation of results.

Physical exercise induces activation of NF-kappaB in human peripheral blood lymphocytes

Current understanding of nuclear factor-kappaB (NF-kappaB) activation is derived mostly from in vitro studies, and in vivo human data are limited. This study provides first evidence showing that physical exercise (80% maximal O2 consumption, 1 h) may trigger NF-kappaB activation, as determined by electrophoretic mobility shift assay, in peripheral blood lymphocytes of physically fit young men. Supershift assay showed that the NF-kappaB protein complex contained the transcriptionally active p65 protein. Plasma levels of NF-kappaB-directed gene products such as tumor necrosis factor-alpha and interleukin-2 receptor confirmed that physical exercise caused NF-kappaB transactivation. Exercise-induced NF-kappaB activation in lymphocytes was associated with elevated levels of lipid peroxidation by-products in the plasma.

Physical activity in first-degree relatives of breast cancer patients

This study sought to evaluate physical activity in women at moderate risk for breast cancer, the correlates of engaging in regular physical activity, and whether physical activity relates to psychological well-being. The results revealed that 55% of women were regularly active. Logistic regression models indicated that positive affect was associated with increased and negative affect was associated with decreased overall and leisure activity. Older, married, and employed women were more likely to engage in household/occupational activity, whereas women who perceived their risk for breast cancer as high were less likely. More educated women and those with higher perceived risk were more likely to engage in leisure activity, and married women were less likely. These results suggest a need to increase activity levels in women at moderate risk for breast cancer, provide variables upon which interventions can be tailored to promote activity, and point to psychological benefits of activity in this population.

Acute immune response in respect to exercise-induced oxidative stress

The relationship between exhaustive exercise, oxidative stress, the protective capacity of the antioxidant defense system and cellular immune response has been determined. Exhaustive exercise in well-trained young men (n=19)-induced leukocytosis, decreased proportion of activated-lymphocyte subsets (CD4+ and CD8+) expressing CD69, decreased lymphocyte mitogenic response to concanavalin A (ConA) and phytohemagglutinin (PHA), increased lipid peroxidation, increased total antioxidant status (TAS) and catalase activity, immediately after exercise. Suppressed blood concentration of T-lymphocyte subsets (CD3+, CD4+, CD8+, NK), increased TAS and blood total glutathione (TGSH) in early recovery period (30 min after exercise) were found. Strong positive correlation was observed between TGSH and lymphocyte mitogenic response to ConA and PHA (r=0.85 and 0.85, respectively) immediately after exercise. Moderate positive correlation was observed between TAS and lymphocyte mitogenic response to PHA (r=0.59) immediately after exercise as well as between TAS and lymphocyte mitogenic response to PHA and ConA (r=0.69 and 0.54, respectively). Moderate to weak correlation was observed between TAS and conjugated dienes with exercise (r=0.66) as well as in 30-min recovery (r=0.50). After a short-term bout of exhaustive exercise, immune system was characterized by acute phase response, which was accompanied with oxidative stress. Suppression of the cellular immunity 30 min after exercise shows that this period is not enough for recovery after exhaustive exercise. The results suggest the interactions between exercise-induced oxidative stress and immune response.

Physical inactivity and smoking increase risk for serious infections in older women

OBJECTIVE

This study examined health and behavioral risk factors for infections that required hospitalization in postmenopausal women who were enrollees of a large health maintenance organization (HMO).

METHODS

Participants were 1,365 generally healthy women aged 55 to 80 years who were followed for up to 6 years. Infection diagnoses listed first in the automated hospital discharge records were used to identify hospitalizations for which infections were the primary cause of admission. Potential risk factors for these serious infections were identified from baseline questionnaire information and automated HMO records from before baseline and during follow-up. Risks for infections associated with hospital admission were examined using multivariate logistic regression methods.

RESULTS

Seventy-three women had a total of 90 hospital admissions in which infection was the primary discharge diagnosis. Behaviors that were independent predictors of infection were physical inactivity (adj. odds ratio = 4.08; 95% CI, 1.73-9.63) and smoking (adj. odds ratio = 2.64; 95% CI, 1.11-6.26). Incident cancer and lung disease were also associated with increased risk of infection. These associations were independent of age, body mass index, functional status, and other measures of health.

CONCLUSIONS

Modifiable risk factors such as physical inactivity and smoking may place older women at risk for serious infections although the causal link is yet to be explained. Further research in this area may lead to new strategies aimed at reducing the serious burden of infections in the older population.

Special feature for the Olympics: effects of exercise on the immune system: exercise effects on systemic immunity

Heavy exertion has acute and chronic influences on systemic immunity. In the resting state, the immune systems of athletes and non-athletes are more similar than disparate with the exception of NK cell activity, which tends to be elevated in athletes. Many components of the immune system exhibit adverse change after prolonged, heavy exertion. These immune changes occur in several compartments of the immune system and body (e.g. the skin, upper respiratory tract mucosal tissue, lung, blood and muscle). Although still open to interpretation, most exercise immunologists believe that during this 'open window' of impaired immunity (which may last between 3 and 72 h, depending on the immune measure) viruses and bacteria may gain a foothold, increasing the risk of subclinical and clinical infection. The infection risk may be amplified when other factors related to immune function are present, including exposure to novel pathogens during travel, lack of sleep, severe mental stress, malnutrition or weight loss.

Physical activity and breast cancer risk in women aged 20-54 years

BACKGROUND/METHODS

Although several studies have suggested that physical activity is associated with a decreased risk of breast cancer, such a decrease has not been found consistently, perhaps because physical activity was assessed in different ways and for restricted periods. Few studies have assessed the risk of breast cancer in relation to lifetime physical activity. We used data from a population-based, case-control study, including 918 case subjects (aged 20-54 years) and 918 age-matched population control subjects, to examine associations between breast cancer risk and physical activity at ages 10-12 years and 13-15 years, lifetime recreational activity, and title of longest held job.

RESULTS

Women who were more active than their peers at ages 10-12 years had a lower risk of breast cancer (odds ratio [OR] = 0.68; 95% confidence interval [CI] = 0.49-0.94). Women who had ever engaged in recreational physical activity had a reduced risk of breast cancer compared with inactive women (OR = 0.70; 95% CI = 0.56-0.88). Neither very early recreational activity (before age 20 years) nor recent activity (last 5 years) was associated with a greater reduction in risk than recreational activity in the intermediate period. Furthermore, women who started recreational activities after age 20 years and women who started earlier and continued their activities throughout adult life experienced a similar reduction in risk. Lean women, i.e., women with a body mass index (weight in kg/[height in m](2)) less than 21. 8 kg/m(2), appeared to have a lower risk associated with recreational physical activity than women with a body mass index greater than 24.5 kg/m(2) (OR = 0.57 [95% CI = 0.40-0.82] and OR = 0. 92 [95% CI = 0.65-1.29], respectively).

CONCLUSIONS

Our findings support the hypothesis that recreational physical activity is associated with a decreased risk of breast cancer. Physical activity in early or recent life does not appear to be associated with additional beneficial effects.