Influence of physical activity in different age and life periods on the risk of breast cancer

The Influence of Physical Training on the Immune System of Rats during N-methyl-N-nitrosourea-Induced Carcinogenesis

Aim: To assess the effect of physical training on the selected parameters of the immune system regarding CD3, CD4, CD8, CD11, CD161, CD45A cell counts in rats treated with N-methyl-N-nitrosourea (MNU). Material and Methods: Thirty-eight female Sprague-Dawley rats were injected intraperitoneally with MNU and were divided into three groups, i.e., sedentary control (SC), the group of moderate-intensity training (MIT) and the group of high-intensity training (HIT). Physical training was supervised immediately after MNU administration and was conducted 5 days per week for 12 weeks on a three-position treadmill. Results: A significant difference was found between SC and training groups in terms of the number of induced tumors per rat (1.57 vs. 0.4, p = 0.05) and in the following lymphocyte subpopulations: CD4+/CD8+ (p = 0.01), CD3−/CD11b+ (p = 0.02), CD3−/CD161+ (p = 0.002), CD3−/CD161− (p = 0.002), CD3+/CD45RA+ (p = 0.003) and CD3−/CD45RA+ (p = 0.005). In terms of the intensity of physical training, the highest efficacy was found for MIT and the following lymphocyte subpopulations: CD3−/CD11b+ (SC vs. MIT, p < 0.001), CD3−/CD161+ (SC vs. MIT, p = 0.002), CD3−/CD161− (SC vs. MIT, p = 0.002), CD3+/CD45RA+ (SC vs. MIT, p = 0.02) and CD3−/CD45RA+ (SC vs. MIT, p < 0.001, MIT vs. HIT, p = 0.02). Furthermore, negative correlations were found between the number of apoptotic cells and CD3−/CD11b (r = −0.76, p = 0.01) in SC and between the number of induced tumors and CD3+/CD8+ (r = −0.61, p = 0.02) and between their volume and CD+/CD8+ (r = −0.56, p = 0.03) in the group of rats undergoing training. Conclusions: Physical training, particularly MIT, affected immune cell function and an altered immune response can be considered a mechanism underlying the effect of exercise on breast cancer development.

Physical activity and risk of benign proliferative epithelial disorders of the breast, in the Women's Health Initiative

BACKGROUND

Recreational physical activity (PA) has been shown to be inversely associated with breast cancer risk. However, the association of recreational PA with benign proliferative epithelial disorders (BPED) of the breast, conditions associated with increased risk of breast cancer, has not been adequately studied.

METHODS

We used data from an ancillary study of benign breast disease conducted among the 68 132 postmenopausal women (aged 50-79 at recruitment) participating in the Women's Health Initiative randomized clinical trials. All clinical trial participants underwent annual or biennial mammogram screening. During the follow-up, for women who reported breast biopsies but were cancer free, the associated histological sections were obtained and subjected to standardized central pathology review. Self-reported recreational PA at baseline (n = 61 684) and at 3 years of the follow-up (n = 55 923) were quantified as metabolic equivalents [MET]-h/week. There were 1624 confirmed BPED cases during an average follow-up time of 7.7 years. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Higher average PA over 4 years was associated with lower risk of non-atypical BPED (P-trend = 0.02). There was a 6% lower risk of non-atypical BPED for every 5 MET-h/week increase between baseline and year 3 (HR = 0.94, 95% CI 0.89-0.99). Compared with women who remained inactive (PAbaseline and PAyear3 <9 MET-h/week), those who became active (PAbaseline<9 MET-h/week to PAyear3 ≥9 MET-h/weekee), remained active (PAbaseline and PAyear3 ≥9 MET-h/week), or decreased activity (PAbaseline ≥9 MET-h/week to PAyear3 <9 MET-h/week) had lower BPED risk.

CONCLUSIONS

Recreational physical activity after menopause was associated with lower BPED risk among postmenopausal women.

Physical activity and Mediterranean diet as potential modulators of osteoprotegerin and soluble RANKL in gBRCA1/2 mutation carriers: results of the lifestyle intervention pilot study LIBRE-1

Purpose

Emerging evidence suggests that the progesterone-mediated receptor activator of nuclear factor κB (RANK)/soluble RANK ligand (sRANKL)/osteoprotegerin (OPG) pathway plays an important role in mammary carcinogenesis and is hyperactivated in germline (g)BRCA1/2 mutation carriers. We analyzed the effects of a 3-month intensive lifestyle intervention within the LIBRE-1 study on the serum levels of OPG and sRANKL and hypothesized that the intervention program provides a beneficial impact on the biomarkers by increasing OPG and reducing sRANKL serum concentrations.

Methods

Serum levels of OPG and sRANKL of 49 gBRCA1/2 mutation carriers were quantified using enzyme-linked immunosorbent assays. We used previously collected blood samples from participants of the prospective LIBRE-1 study, who were randomized into an intervention group (IG), increasing physical activity and adherence to the Mediterranean diet (MedD) through supervised sessions from study entry to the first study visit after 3 months and a usual-care control group (CG). Differences in biomarker levels before and after the 3-month intervention were tested within and between study groups.

Results

The lifestyle intervention resulted in a significant increase in OPG for participants in both the IG (q = 0.022) and CG (q = 0.002). sRANKL decreased significantly in the IG (q = 0.0464) and seemed to decrease in the CG (q = 0.5584). An increase in the intake of Omega-3 polyunsaturated fatty acids was significantly associated with an increase in OPG (r = 0.579, q = 0.045). Baseline serum levels of sRANKL were a strong predictor for the change of sRANKL in the course of the intervention (ß-estimate = − 0.70; q = 0.0018). Baseline physical fitness (assessed as VO₂peak) might predict the change of OPG in the course of the intervention program (ß-estimate = 0.133 pg/ml/ml/min/kg; p = 0.0319; q = 0.2871).

Conclusion

Findings from this pilot study seem to confirm our hypothesis by showing an increase in OPG and decrease in sRANKL over a 3-month lifestyle intervention and suggest that increased physical activity and adherence to the MedD are potent modulators of the biomarkers OPG and potentially sRANKL.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10549-021-06400-7.

Dietary molecules and experimental evidence of epigenetic influence in cancer chemoprevention: An insight

The world-wide rate of incidence of cancer disease has been only modestly contested by the past and current preventive and interventional strategies. Hence, the global effort towards novel ideas to contain the disease still continues. Constituents of human diets have in recent years emerged as key regulators of carcinogenesis, with studies reporting their inhibitory potential against all the three stages vis-a-vis initiation, promotion and progression. Unlike drugs which usually act on single targets, these dietary factors have an advantage of multi-targeted effects and pleiotropic action mechanisms, which are effective against cancer that manifest as a micro-evolutionary and multi-factorial disease. Since most of the cellular targets have been identified and their consumption considered relatively safe, these diet-derived agents often appear as molecules of interest in repurposing strategies. Currently, many of these molecules are being investigated for their ability to influence the aberrant alterations in cell's epigenome for epigenetic therapy against cancer. Targeting the epigenetic regulators is a new paradigm in cancer chemoprevention which acts to reverse the warped-up epigenetic alterations in a cancer cell, thereby directing it towards a normal phenotype. In this review, we discuss the significance of dietary factors and natural products as chemopreventive agents. Further, we corroborate the experimental evidence from existing literature, reflecting the ability of a series of such molecules to act as epigenetic modifiers in cancer cells, by interfering with molecular events that map the epigenetic imprints such as DNA methylation, histone acetylation and non-coding RNA mediated gene regulation.

Influence of physical activity at a young age and lifetime physical activity on the risks of 3 obesity-related cancers: systematic review and meta-analysis of observational studies

CONTEXT

Excess weight has been linked to increased risks of 13 types of cancers. Physical activity is a non-nutritional modifiable lifestyle factor that is not only crucial for weight control but is also known to regulate hormones and metabolic pathways that may contribute to carcinogenesis. There is solid evidence that being physically active during middle and late adulthood lowers the risks of 3 obesity-related cancers, namely breast cancer, colon cancer, and endometrial cancer. However, the associations between physical activity at a young age (childhood, adolescence, and young adulthood; age 5 to ≤30 yr) and lifetime physical activity and the risks of breast cancer, colon cancer, and endometrial cancer are less defined.

OBJECTIVE

The present systematic review and meta-analysis of observational studies was performed in accordance with the MOOSE guidelines to determine whether physical activity at a young age and lifetime physical activity may lower the risks of breast cancer, colon cancer, and endometrial cancer.

DATA SOURCES

The PubMed and Web of Science databases were searched for relevant observational studies published from inception to July 2018.

STUDY SELECTION

Observational studies (prospective cohort, case-cohort, nested case-control, historical cohort, and case-control) were considered relevant if they investigated the association between physical activity at a young age or lifetime physical activity and the risks of developing selected cancers.

DATA EXTRACTION

A random-effects meta-analysis was performed to generate the summary relative risk (RR) with 95%CI for the highest vs the lowest category of physical activity of any type.

RESULTS

Eighty publications were included in the present meta-analysis. Higher physical activity at a young age was associated with lower risks of breast cancer (RR 0.81, 95%CI 0.76, 0.87) and colon cancer (RR 0.67, 95%CI 0.50, 0.88). Similarly, lifetime physical activity was inversely associated with the risks of breast cancer (RR 0.79, 95%CI 0.72, 0.86) and colon cancer (RR 0.75, 95%CI 0.69, 0.82). For breast cancer, menopausal status did not appear to modify the observed inverse association. The benefit with respect to endometrial cancer risk reduction was only observed with higher lifetime physical activity (RR 0.77, 95%CI 0.67, 0.88), not with higher physical activity at a young age (RR 0.89, 95%CI 0.73, 1.07).

CONCLUSIONS

Being physically active over a lifetime, starting from early childhood, may lower the risks of developing breast cancer, colon cancer, and endometrial cancer.

Women’s occupational exposure to polycyclic aromatic hydrocarbons and risk of breast cancer

Objective

To estimate the association between occupational polycyclic aromatic hydrocarbon (PAH) exposure and female breast cancer.

Methods

Lifetime work histories for 1130 cases and 1169 controls from British Columbia and Ontario (Canada) were assessed for PAH exposure using a job-exposure matrix based on compliance measurements obtained during US Occupational Safety and Health Administration workplace safety inspections.

Results

Exposure to any level of PAHs was associated with an increased risk of breast cancer (OR=1.32, 95% CI: 1.10 to 1.59), as was duration at high PAH exposure (for >7.4 years: OR=1.45, 95% CI: 1.10 to 1.91; ptrend=0.01), compared with women who were never exposed. Increased risk of breast cancer was most strongly associated with prolonged duration at high occupational PAH exposure among women with a family history of breast cancer (for >7.4 years: OR=2.79, 95% CI: 1.25 to 6.24; ptrend<0.01).

Conclusions

Our study suggests that prolonged occupational exposure to PAH may increase breast cancer risk, especially among women with a family history of breast cancer.

Physical activity and lung cancer risk in men and women

PURPOSE

Although evidence has accumulated that recreational physical activities (PA) may reduce lung cancer risk, there is little evidence concerning the possible role of a potentially more important source of PA, namely occupational PA. We investigated both recreational and lifetime occupational PA in relation to lung cancer risk in a population-based case-control study in Montreal, Canada (N_CASES = 727; N_CONTROLS = 1,351).

METHODS

Unconditional logistic regression was used to estimate odds ratios (OR), separately for men and women, adjusting for smoking, exposure to occupational carcinogens, and sociodemographic and lifestyle factors.

RESULTS

In both sexes, increasing recreational PA was associated with a lower lung cancer risk (OR_MEN = 0.66, 95% confidence interval (CI) 0.47-0.92; OR_WOMEN = 0.55, 95% CI 0.34-0.88, comparing the highest versus lowest tertiles). For occupational PA, no association was observed among women, while increasing occupational PA was associated with increased risk among men (OR_MEN = 1.96, 95% CI 1.27-3.01). ORs were not modified by occupational lung carcinogen exposure, body mass index, and smoking level; results were similar across lung cancer histological types.

CONCLUSIONS

Our results support the previous findings for recreational PA and lung cancer risk. Unexpectedly, our findings suggest a positive association for occupational PA; this requires replication and more detailed investigation.

Physical activity in leisure-time and risk of cancer: 14-year follow-up of 28,000 Danish men and women

Aim: The preventive effect of physical activity on risk of cancer in general remains controversial. This study aimed at assessment of the associations between leisure- time physical activity and incidence of cancer in the general population of adult men and women. Methods: 13,216 women and 18,718 men aged 20—93 years selected from the general population participated in a health examination including a questionnaire with information on physical activity, smoking, alcohol intake, postmenopausal hormones, and socioeconomic status. Incident cases of cancers where recorded during a follow-up period of 14 years. The six most frequent cancer cases in both sexes were included in this analysis. Results: A highly significant inverse association was seen between vigorous physical activity in leisure time and cancer of the ovary, adjusted rate ratio being 0.33 (95% CI 0.16—0.67; p=0.001) for the most physical active women. In men there was a highly significant increase for non-melanoma skin cancer, with adjusted rate ratio of 1.72 (95% CI 1.23—2.40; p=0.001), for the most active men and vigorous activity was associated with a non-significant lower risk of colon cancer, the adjusted rate ratio being 0.72 (95% CI 0.47—1.11; p=0.06). Conclusion: Generally, there were no, or only weakly, inverse associations between physical activity in leisure time and incidence of cancer, except for cancer of the ovary.

Impact of Maternal Exercise during Pregnancy on Offspring Chronic Disease Susceptibility

Maternal behaviors during pregnancy have been reported to impact offspring health in adulthood. In this article we explore the novel hypothesis that exercise during pregnancy can protect against chronic disease susceptibility in the offspring. To date, research has demonstrated that improvements in metabolic outcomes, cardiovascular risk, and cancer can occur in response to maternal exercise during pregnancy.

Association between Daytime Activity, Fatigue, Sleep, Anxiety, Depression, and Symptom Burden in Advanced Cancer Patients: A Preliminary Report

BACKGROUND

There is limited research in advanced cancer patients (ACP) regarding association between objectively measured daytime activity and sleep (as measured by actigraphy), patient characteristics, and cancer symptoms (fatigue, sleep, anxiety, depression, cachexia, and symptom distress scores [SDSs]).

OBJECTIVES

Our aim of the study was to determine the association between mean daytime activity (MDTA) and the following items: fatigue (FACIT-F), SDSs (Edmonton Symptom Assessment Scale [ESAS]), sleep quality (Pittsburg Sleep Quality Index [PSQI]), objective sleep variables (OSV) (sleep onset, sleep efficacy, wake after sleep onset, total sleep time), anxiety and depression (Hospital Anxiety and Depression Scale [HADS]), body composition scores, and overall survival (OS). We also examined the association between sleep [PSQI and OSV scores] and FACIT-F, HADS, and ESAS.

METHODS

Secondary analysis of a recent clinical trial of cancer-related fatigue in advanced cancer (NCT00424099). Association between MDTA and OSV (measured by actigraphy) during the first week of the study and patient characteristics, symptoms (FACIT-F, ESAS, HADS, and PSQI), and OS were analyzed.

RESULTS

Seventy-nine eligible patients were evaluable. The median age was 57 years. Median MDTA was 248.43 counts/minute. Multivariate analysis shows that low MDTA was significantly associated with age, gender, Functional Assessment of Cancer Therapy (FACT)-Functional Well-Being (FWB), ESAS dyspnea, HADS-anxiety, and total sleep time. MDTA was not associated with FACIT-F (p = 0.997) and OS (p = 0.18). Sleep quality (PSQI) was significantly associated with FACIT-F, HADS, ESAS anxiety, and depression, but none of these variables was associated with OSV.

CONCLUSION

In ACP, lower MDTA was significantly associated with age, gender, FACT-FWB, ESAS dyspnea, HADS-anxiety, and total sleep time. Both sleep quality and cancer-related fatigue scores were strongly associated with depression and anxiety. More research is needed.

A prospective study of occupational physical activity and breast cancer risk

PURPOSE

Physical activity has been associated with reduced breast cancer risk, but studies of occupational activity have produced inconsistent results. The purpose of this study was to evaluate the relationship between occupational physical activity and breast cancer in a prospective study of women with a family history of breast cancer.

METHODS

We studied breast cancer risk in 47,649 Sister Study participants with an occupational history. Information on occupational activity and breast cancer risk factors was collected during baseline interviews (2004-2009). Physical activity at each job was self-reported and categorized as mostly sitting, sitting and standing equally, mostly standing, and active. Multivariable Cox proportional hazards regression was used to evaluate associations between lifetime occupational activity and incident breast cancer, after adjusting for established risk factors and recreational activity.

RESULTS

During follow-up, a total of 1,798 breast cancer diagnoses were reported. Compared with women who did not spend any time in active jobs, women who spent a high proportion (≥75%) of their working years in active jobs had a reduced risk of breast cancer (HR 0.72; 95% CI 0.52-0.98). Associations were strongest among overweight (HR 0.64; 95% CI 0.42-0.98) and postmenopausal (HR 0.67; 95% CI 0.45-0.98) women.

CONCLUSIONS

Occupational activity was associated with a reduced risk of breast cancer. Occupational activity is a domain of physical activity that should be further examined in studies of postmenopausal breast cancer risk. Additional research is necessary to better understand the mechanisms underlying the relationships between occupational activity, body size, and breast cancer.

Maternal exercise during pregnancy reduces risk of mammary tumorigenesis in rat offspring

Breast cancer is the most common cancer among women. Emerging research indicates that modifying lifestyle factors during pregnancy may convey long-term health benefits to offspring. This study was designed to determine whether maternal exercise during pregnancy leads to reduced mammary tumorigenesis in female offspring. Pregnant rats were randomly assigned to exercised and sedentary groups, with the exercised group having free access to a running wheel and the sedentary group housed with a locked wheel during pregnancy. Female pups from exercised or sedentary dams were weaned at 21 days of age and fed a high fat diet without access to a running wheel. At 6 weeks, all pups were injected with the carcinogen N-methyl-N-nitrosourea. Mammary tumor development in all pups was monitored for 15 weeks. Pups from exercised dams had a substantially lower tumor incidence (42.9%) compared with pups from sedentary dams (100%). Neither tumor latency nor histological grade differed between the two groups. These data are the first to demonstrate that exercise during pregnancy potentiates reduced tumorigenesis in offspring. This study provides an important foundation towards developing more effective modes of behavior modification for cancer prevention.

The effect of physical training on the N-methyl-N-nitrosourea-induced mammary carcinogenesis of Sprague-Dawley rats

The impact of physical activity on carcinogenesis has been demonstrated in many studies. Taking into account the discrepant results of physical exercise on the cell proliferation and apoptosis of breast cancer, we aimed to examine the impact of physical training on N-methyl-N-nitrosourea-(MNU)-induced mammary carcinogenesis. Fifty female rats were divided into four groups according to the intensity of physical activity they undertook. The number of developed tumors, tumor volume, and histopathological diagnoses were noted. Apoptosis and cell proliferation were studied by the number of TUNEL-positive and Ki-67-expressing cells. We demonstrated a statistically significant decrease in the tumor number between all trained groups and the control group. The results were most pronounced in the group with a moderate intensity of training. Moreover, we showed a decrease in tumor volume as training intensity increased, though the differences were not statistically significant. The mean number of TUNEL-positive cancer cells was significantly higher in the training groups than in the control group. These data suggest that physical training, especially of moderate intensity, may alleviate MNU-induced mammary carcinogenesis. The results could suggest that physical exercise-induced apoptosis may be a protective mechanism.

Physical activity and the risk of postmenopausal breast cancer - the Norwegian Women and Cancer Study

Background

The relationship between physical activity (PA) throughout life and the risk of postmenopausal breast cancer overall and by estrogen receptor (ER) and progesterone receptor (PR) status, has been reported, but without consistent results. The present study aimed to investigate PA from young age to adulthood in participants of the Norwegian Women and Cancer (NOWAC) Study, in order to determine whether changes in PA level affect the risk of postmenopausal breast cancer.

Methods

1767 invasive breast cancer cases were identified among 80,202 postmenopausal participants of the NOWAC Study during 8.2 years of median follow-up. PA levels at age 14 years, 30 years and at cohort enrollment were obtained via a self-administered questionnaire. Multivariate Cox proportional hazard regression models were used to estimate relative risks and 95% confidence intervals of the risk of postmenopausal breast cancer overall and by ER/PR status.

Results

Risk of postmenopausal breast cancer overall and by ER/PR status was not associated with physical activity level at enrollment. Women with a low PA level at age 30 had an increased risk of ER+/PR + breast tumors (P for trend = 0.04) compared to women with a moderate physical activity level at age 30. Women with a low physical activity level at all three periods of life had a 20% significantly reduced risk of postmenopausal breast cancer, as well as a reduced risk of ER+/PR + and ER+/PR- breast tumors, compared with women who maintained a moderate physical activity level. However, when analyses were corrected for multiple tests, the result was no longer statistically significant. The findings were consistent over strata of age, body mass index and use of hormone replacement therapy.

Conclusions

The study results from this large Norwegian cohort do not support an association between physical activity at different periods of life and the risk of postmenopausal breast cancer.

Solid tumor second primary neoplasms: who is at risk, what can we do?

Eighteen percent of incident malignancies in the United States are a second (or subsequent) cancer. Second primary neoplasms (SPNs), particularly solid tumors, are a major cause of mortality and serious morbidity among cancer survivors successfully cured of their first cancer. Multiple etiologies may lead to a cancer survivor subsequently being diagnosed with an SPN, including radiotherapy for the first cancer, unhealthy lifestyle behaviors, genetic factors, aging, or an interaction between any of these factors. In this article, we discuss these factors and synthesize this information for use in clinical practice, including preventive strategies and screening recommendations for SPNs.

Increased risk of breast cancer associated with long-term shift work in Canada

OBJECTIVES

Long-term night work has been suggested as a risk factor for breast cancer; however, additional studies with more comprehensive methods of exposure assessment to capture the diversity of shift patterns are needed. As well, few previous studies have considered the role of hormone receptor subtype.

METHODS

Relationships between night shift work and breast cancer were examined among 1134 breast cancer cases and 1179 controls, frequency-matched by age in Vancouver, British Columbia, and Kingston, Ontario. Self-reported lifetime occupational histories were assessed for night shift work, and hormone receptor status obtained from tumour pathology records.

RESULTS

With approximately one-third of cases and controls ever employed in night shift work, associations with duration demonstrated no relationship between either 0-14 or 15-29 years, while an association was apparent for ≥30 years (OR=2.21, 95% CI 1.14 to 4.31). This association with long-term night shift work is robust to alternative definitions of prolonged shift work, with similar results for both health and non-health care workers.

CONCLUSIONS

Long-term night shift work in a diverse mix of occupations is associated with increased breast cancer risk and not limited to nurses, as in most previous studies.

Association of pre-diagnosis physical activity with recurrence and mortality among women with breast cancer

Evidence is emerging that physical activity (PA) may improve overall survival after breast cancer diagnosis. However, the effect of PA on breast cancer recurrence and on cause-specific mortality is less investigated. We assessed the association of pre-diagnosis PA with recurrence, overall and cause-specific survival in a prospective cohort study in Germany including 3,393 non-metastatic breast cancer patients aged 50-74 years. Cox proportional hazards models were calculated adjusted for relevant prognostic factors. During a median follow-up of 5.6 years, 367 patients deceased. Overall mortality was significantly inversely associated with pre-diagnosis recreational PA. However, this effect was mainly attributed to deaths due to causes other than breast cancer. Multiple fractional polynomial analyses yielded a nonlinear association with markedly increased non-breast cancer mortality for women who did not engage in any sports or cycling in the years before the breast cancer diagnosis with a hazard ratio (HR, none vs. any) of 1.71, 95% confidence interval (1.16, 2.52). There were no further risk reductions with increasing activity levels. The association with breast cancer-specific mortality showed a similar dose-response but was far less pronounced with HR (none vs. any) = 1.22 (0.91, 1.64). In contrast, regarding cancer recurrence the dose-response was linear. However, this association was restricted to estrogen/progesterone receptor-negative (ER-/PR-) cases (p interaction = 0.033) with HR (highest vs. no recreational PA) = 0.53 (0.24, 1.16), p trend = 0.0045. Thus, breast cancer patients with a physically inactive lifestyle pre-diagnosis may decease prematurely irrespective of their cancer prognosis. Higher levels of exercise may reduce the risk of recurrence of ER-/PR- breast tumors.

Perioperative exercise for chronic liver injury patients with hepatocellular carcinoma undergoing hepatectomy

BACKGROUND

The aim of this study was to examine the outcomes of exercise therapy in patients with hepatocellular carcinoma who underwent hepatectomy.

METHODS

Fifty-one patients with hepatocellular carcinoma were randomized to diet therapy alone (n = 25) or to exercise in addition to diet therapy (n = 26). Exercise at the anaerobic threshold of each patient was started 1 month preoperatively, resumed from 1 week postoperatively, and continued for 6 months.

RESULTS

Whole body mass and fat mass in the exercise group compared with the diet group were significantly decreased at 6 months postoperatively. Fasting serum insulin and the homeostasis model assessment score were also significantly decreased. At 6 months, anaerobic threshold and peak oxygen consumption were significantly increased, while serum insulin and insulin resistance were significantly improved in a high-frequency exercise subgroup compared with a low-frequency group.

CONCLUSIONS

Perioperative exercise therapy for patients with hepatocellular carcinoma with liver dysfunction may improve insulin resistance associated with hepatic impairment and suggests a benefit to the early resumption of daily exercise after hepatectomy.

Therapeutic potential of stem cells expressing suicide genes that selectively target human breast cancer cells: evidence that they exert tumoricidal effects via tumor tropism (review)

Breast cancer is the most prevalent cancer in women worldwide and is classified into ductal and lobular carcinoma. Breast cancer as well as lobular carcinoma is associated with various risk factors such as gender, age, female hormone exposure, ethnicity, family history and genetic risk factor-associated genes. Genes associated with a high risk of developing breast cancer include BRCA1, BRCA2, p53, PTEN, CHEK2 and ATM. Surgery, chemotherapy, radiotherapy and hormone therapy are used to treat breast cancer but these therapies, except for surgery, have many side-effects such as alopecia, anesthesia, diarrhea and arthralgia. Gene-directed enzyme/prodrug therapy (GEPT) or suicide gene therapy, may improve the therapeutic efficacy of conventional cancer radiotherapy and chemotherapy without side-effects. GEPT most often involves the use of a viral vector to deliver a gene not found in mammalian cells and that produces enzymes which can convert a relatively non-toxic prodrug into a toxic agent. Examples of these systems include cytosine deaminase/5-fluorocytosine (CD/5-FC), carboxyl esterase/irinotecan (CE/CPT-11), and thymidine kinase/ganciclovir (TK/GCV). Recently, therapies based on genetically engineered stem cells (GESTECs) using a GEPT system have received a great deal of attention for their clinical and therapeutic potential to treat breast cancer. In this review, we discuss the potential of GESTECs via tumor tropism effects and therapeutic efficacy against several different types of cancer cells. GESTECs represent a useful tool for treating breast cancer without inducing injuries associated with conventional therapeutic modalities.

[Physical activity and tumor diseases]

Physical activity is an important health measure for many diseases but in the past its role in cancer control has been understudied and underappreciated. This chapter updates a review of physical activity and cancer risk. Overall, the research to date suggests that physical activity reduces the risk of developing some forms of cancer, helps cancer survivors cope with and recover from treatment, improves the long-term health of cancer survivors and possibly even reduces the risk of recurrence and extends survival in some cancer survivor groups. Much research remains to be done in this field but the compelling data produced so far suggests that physical activity has an important effect on the development of cancer and precursor stages.

Case-control study of lifetime total physical activity and endometrial cancer risk

A population-based case–control study of physical activity and endometrial cancer risk was conducted in Alberta between 2002 and 2006. Incident, histologically confirmed cases of endometrial cancer (n = 542) were frequency age-matched to controls (n = 1,032). The Lifetime Total Physical Activity Questionnaire was used to measure occupational, household, and recreational activity levels. Multivariable logistic regression analyses were conducted. Total lifetime physical activity reduced endometrial cancer risk (odds ratio [OR] for >129 vs. <82 MET-h/week/year = 0.86, 95% confidence interval [95% CI]: 0.63, 1.18). By type of activity, the risks were significantly decreased for greater recreational activity (OR = 0.64, 95% CI: 0.47, 0.87), but not for household activity (OR = 1.09, 95% CI: 0.75, 1.58) and/or occupational activity (OR = 0.90, 95% CI: 0.67, 1.20) when comparing the highest to lowest quartiles. For activity performed at different biologically defined life periods, some indication of reduced risks with activity done between menarche and full-term pregnancy and after menarche was observed. When examining the activity by intensity of activity (i.e., light <3, moderate 3–6, and vigorous >6 METs), light activity slightly decreased endometrial cancer risk (OR = 0.68, 95% CI: 0.48, 0.97) but no association with moderate or vigorous intensity activity was found. Endometrial cancer risk was increased with sedentary occupational activity by 28% (95 CI%: 0.89, 1.83) for >11.3 h/week/year versus ≤2.4 h/week/year or by 11% for every 5 h/week/year spent in sedentary behavior. This study provides evidence for a decreased risk between lifetime physical activity and endometrial cancer risk and a possible increased risk associated with sedentary behavior.

Weight, dietary behavior, and physical activity in childhood and adolescence: implications for adult cancer risk

Lifestyle factors related to energy balance, including weight, dietary behavior and physical activity, are associated with cancer risk. The period of childhood and growth into adolescence and early adulthood may re-present a 'cumulative risk' for later adult-onset cancers. We review a number of epidemiologic studies that have examined associations among childhood and adolescent body size, diet, and physical activity with adult cancer risk. These studies suggest that unhealthy behaviors that develop early in life and persist over time may increase the risk of some cancer types, such as premenopausal breast, ovarian, endometrial, colon and renal cancer, adversely affect cancer-related morbidities, and increase mortality. Continued research is needed to further determine and refine how timing and degree of such exposures in early childhood and adolescence relate to adult cancer risk. Presently, sufficient evidence suggests a continued need for stronger primary prevention in cancer and obesity research via modified lifestyle behaviors earlier in the developmental spectrum, i.e. during childhood and adolescence.

Physical activity and postmenopausal breast cancer: effect modification by breast cancer subtypes and effective periods in life

Physical activity (PA) has been inversely associated with postmenopausal breast cancer risk. However, it is unclear how and in which life periods PA may be effective to reduce breast cancer risk. Moreover, the evidence is still not judged as 'convincing' as there is some heterogeneity among study results. Most studies regarded breast cancer as a single disease, at best separated by menopausal status. Yet, breast cancers are heterogeneous and likely have different etiologies. Therefore, we analyzed the association of PA with different breast cancer subtypes in 3,414 postmenopausal cases and 6,569 controls from a case-control study on breast cancer conducted 2002-2005 in Germany (MARIE study). PA in the age periods 30-49 and 50+ years was assessed, including leisure-time PA (sports, cycling, walking) and non-recreational PA (occupational and household activities). There was a significant protective effect of leisure-time PA for ER+/PR+ carcinomas (adjusted odds ratio = 0.71, 95% confidence interval: 0.60, 0.85; trend P = 0.0001), but no effect for ER-/PR- carcinomas. Moreover, looking at physical activity pattern over time, the effect of PA after menopause on reducing breast cancer risk was more pronounced than the effect of PA before menopause. Overall, effects of PA were independent from adult weight gain, body mass index, and energy intake. These findings suggest that leisure-time PA after menopause may reduce postmenopausal breast cancer risk at least in part via hormonal pathways and not solely by changing body composition. Inactive postmenopausal women should be encouraged to become physically active even later in life.

Physical activity and premenopausal breast cancer: an examination of recall and selection bias

BACKGROUND

Compared with cohort studies, case-control investigations have tended to report clearer protective associations for the relationship between physical activity and premenopausal breast cancer risk.

METHODS

We conducted a case-control study within the Nurses' Health Study II cohort to examine whether recall or selection bias could explain the stronger protective associations. Self-reported total recreational physical activity during adulthood and over a woman's lifetime (ages 12 years to current) were assessed in 1997 before diagnosis and, again, from one to seven years after breast cancer diagnosis among the same women.

RESULTS

Eighty-seven percent of cases (417 of 479) and 82% of controls (390 of 474) responded. Selection bias was observed for activity during adulthood but not for activity over a woman's lifetime. Recall bias was not observed in the direction we expected: the odds ratios (ORs) for breast cancer comparing the highest versus lowest quintile of prospectively reported total activity were not significantly different than the corresponding estimates from retrospective reports (e.g., lifetime activity: prospective OR = 0.58, 95% CI: 0.37, 0.93 versus retrospective OR = 0.80; 95% CI: 0.50, 1.29).

CONCLUSION

Recall or selection bias may not have been accounted for protective associations among case-control investigations examining lifetime recreational physical activity and breast cancer. Selection bias related to recreational physical activity during adulthood and random error in the measurement of physical activity remain concerns.

Prepubertal physical activity up-regulates estrogen receptor beta, BRCA1 and p53 mRNA expression in the rat mammary gland

Findings in BRCA1 mutation carriers suggest that physical activity, particularly during childhood, may be linked to a reduced risk of developing breast cancer. We investigated whether physical activity at puberty alters the expression of BRCA1 and two other tumor suppressor genes--p53 and estrogen receptor (ER)-beta--in rats. In addition, the effects on ER-alpha expression, mammary proliferation and functional epithelial differentiation were investigated as markers of altered mammary cancer risk in rats exposed to regular physical activity at puberty. Female Sprague Dawley rat pups were randomized to voluntary exercise, sham-exercise control and non-manipulated control groups. Treadmill training (20-25 m/min, 15% grade, 30 min/day, 5 days/week) started on postnatal day 14 and continued through day 32. Third thoracic mammary glands (n = 5 per group and age) were obtained at days 32, 48 and 100 and assessed for changes in morphology through wholemounts, and at 100 days cell proliferation by using Ki67 staining, protein levels of ER-alpha and ER-beta by immunohistochemistry, and mRNA expression levels of BRCA1, p53, ER-alpha and ER-beta by real-time PCR. Mammary glands of rats exposed to exercise during puberty contained fewer terminal end buds (TEBs) and a higher number of differentiated alveolar buds and lobules than the sham controls. However, cell proliferation was not significantly altered among the groups. ER-alpha protein levels were significantly reduced, while ER-beta levels were increased in the mammary ducts and lobular epithelial structures of 100-day old rays which were voluntarily exercised at puberty, compared to sham controls. ER-beta, BRCA1 and p53 mRNA levels were significantly higher in the mammary glands of 100-day-old exercised versus sham control rats. Pubertal physical activity reduced mammary epithelial targets for neoplastic transformation through epithelial differentiation and it also up-regulated tumor suppressor genes BRCA1, p53 and ER-beta, and reduced ER-alpha/ER-beta ratio in the mammary gland. It remains to be determined whether the up-regulation of BRCA1, and perhaps p53, explains the protective effect of childhood physical activity against breast cancer in women who carry a germline mutation in one of the BRCA1 alleles.

The role of early life genistein exposures in modifying breast cancer risk

Review of the existing literature suggests that consumption of soy foods or an exposure to a soy isoflavone genistein during childhood and adolescence in women, and before puberty onset in animals, reduces later mammary cancer risk. In animal studies, an exposure that is limited to the fetal period or adult life does not appear to have the same protective effect. A meta-analysis of human studies indicates a modest reduction in pre- and postmenopausal risk when dietary intakes are assessed during adult life. These findings concur with emerging evidence indicating that timing may be vitally important in determining the effects of various dietary exposures on the susceptibility to develop breast cancer. In this review, we address the mechanisms that might mediate the effects of an early life exposure to genistein on the mammary gland. The focus is on changes in gene expression, such as those involving BRCA1 and PTEN. It will be debated whether mammary stem cells are the targets of genistein-induced alterations and also whether the alterations are epigenetic. We propose that the effects on mammary gland morphology and signalling pathways induced by pubertal exposure to genistein mimic those induced by the oestrogenic environment of early first pregnancy.

Role of physical activity in modulating breast cancer risk as defined by APC and RASSF1A promoter hypermethylation in nonmalignant breast tissue

Physical activity reduces breast cancer risk. Promoter hypermethylation of the tumor suppressor genes APC and RASSF1A, which is potentially reversible, is associated with breast cancer risk. We conducted a cross-sectional study in 45 women without breast cancer to determine the association of physical activity with promoter hypermethylation of APC and RASSF1A in breast tissue. We used quantitative methylation-specific PCR to test the methylation status of APC and RASSF1A, and questionnaires to assess study covariates and physical activity (measured in metabolic equivalent hours per week). In univariate analyses, the study covariate, benign breast biopsy number, was positively associated with promoter hypermethylation of APC (P = 0.01) but not RASSF1A. Mulitvariate logistic regression indicated that, although not significant, physical activities for a lifetime [odds ratio (OR), 0.57; 95% confidence interval (95% CI), 0.22-1.45; P = 0.24], previous 5 years (OR, 0.62; 95% CI, 0.34-1.12; P = 0.11), and previous year (OR, 0.72; 95% CI, 0.43-1.22; P = 0.22) were inversely related to promoter hypermethylation of APC but not RASSF1A for all physical activity measures. Univariate logistic regression indicated that physical activities for a lifetime, previous 5 years, and previous year were inversely associated with benign breast biopsy number, and these results were approaching significance for lifetime physical activity (OR, 0.41; 95% CI, 0.16-1.01; P = 0.05) and significant for physical activity in the previous 5 years (OR, 0.57; 95% CI, 0.34-0.94; P = 0.03). The study provides indirect evidence supporting the hypothesis that physical activity is inversely associated with promoter hypermethylation of tumor suppressor genes, such as APC, in nonmalignant breast tissue.

Lifetime recreational and occupational physical activity and risk of in situ and invasive breast cancer

Numerous studies have observed reduced breast cancer risk with increasing levels of physical activity, yet these findings have been inconsistent about optimal times of activity and effect modification by other factors. We investigated the association between recreational and occupational physical activity and breast cancer risk in a population-based case-control study in Massachusetts, New Hampshire, and Wisconsin. During structured telephone interviews, 7,630 controls, 1,689 in situ, and 6,391 invasive breast cancer cases, ages 20 to 69 years, reported lifetime history of recreational physical activity and occupation. Neither lifetime recreational nor strenuous occupational physical activity appeared to be associated with risk of breast carcinoma in situ. In contrast, recreational physical activity was associated with a reduced risk of invasive breast cancer. After adjustment for potentially confounding factors, women averaging >6 h per week of strenuous recreational activity over their lifetime had a 23% reduction in the odds ratio of invasive breast cancer when compared with women reporting no recreational activity (95% confidence interval, 0.65-0.92; P(trend) = 0.05). However, this reduction in risk was limited to women without a first-degree family history of breast cancer (P(interaction) = 0.02). Inverse associations were observed for physical activity early in life, in the postmenopausal years, and in the recent past, but these findings were confined to women without a family history of breast cancer. Lifetime strenuous occupational activity was not associated with invasive breast cancer risk. These results provide further evidence that, for most women, physical activity may reduce the risk of invasive breast cancer.

Lifetime physical activity and the risk of breast cancer: a case-control study

BACKGROUND

The association between breast cancer and lifetime histories of physical activity was studied to determine whether exercise may reduce development of this cancer.

METHODS

The case-control study was based on 250 women living in the Region of Western Pomerania with histological confirmed breast cancer operated during 1999-2003 in the Szczecin hospitals, and 301 controls, free of any cancer diagnosis, aged 35-75 years. Physical activity was assessed using a self-administered questionnaire with questions on type of activity, duration, frequency, and intensity for each type of activity. Data on physical activity from exercise/sports, household and outdoor chores, and occupational activity separately throughout a woman's lifetime were collected. Recreational physical activity was examined for the four age periods (14-20, 21-34, 35-50, and after the age of 50 years). Logistic regression was used to compute odds ratios (ORs) and 95% confidence intervals (CI) and a full assessment of confounding was included in analysis.

RESULTS

Lifetime total physical activity among all women was associated with a reduced breast cancer risk; after controlling for potential confounders the multivariate ORs associated with <110, 110-150, and >150 metabolic equivalent (MET)-hours/week/year were 1.00 (referent), 0.60 (95% CI: 0.60-1.06), and 0.43 (95% CI: 0.25-0.75), respectively (P(trend)=0.004). Analyses by type of lifetime activity for household and recreational activities revealed significant risk reductions: 1.00 (referent); 0.51, 95% CI: 0.29-0.87; 0.54, 95% CI: 0.31-0.94 (P(trend)=0.002), and 1.00 (referent); 0.54, 95% CI: 0.31-0.94; 0.40, 95% CI: 0.22-0.70 (P(trend)<0.001), respectively. For lifetime occupational activity a modest association could not be ruled out when measured the activity by average annual hours/week; the ORs were 0.51, 95% CI: 0.29-0.91, and 0.58, 95% CI: 0.33-1.00, the inverse trend in risk was not significant (P(trend)=0.51). Women who started recreational activity after age of 20 years had much more higher breast cancer risk than either those who were active between ages 14 and 20 years and were inactive after age 20 years or continued their activity throughout adult life.

CONCLUSIONS

These data are in concordance with the hypothesis that lifetime total physical activity is associated with decreased breast cancer risk. They also suggest that recreational physical activity at ages 14-20 years is the most beneficial. In addition, these findings confirm the majority of previous reports which implicated physical inactivity as important risk factor for breast cancer.

Physical Activity and Breast Cancer

BACKGROUND

Many epidemiologic studies have found an association between physical activity and breast cancer risk, although this has not been a consistent finding.

METHODS

Studies were identified through a systematic review of literature available on PubMed through February 2006. We included all cohort and case-control studies that assessed total or leisure time activities in relation to occurrence or mortality of breast cancer. The fully adjusted risk estimates and 95% confidence intervals for the highest versus lowest level of activity were documented for each study as well as evidence for a dose-response relationship. Methodologic quality was also assessed. Due to statistical and methodologic heterogeneity among studies, we did not carry out statistical pooling. To draw conclusions, we performed a best-evidence synthesis taking study quality into account.

RESULTS

Nineteen cohort studies and 29 case-control studies were evaluated. There was strong evidence for an inverse association between physical activity and postmenopausal breast cancer with risk reductions ranging from 20% to 80%. For premenopausal breast cancer, however, the evidence was much weaker. For pre- and postmenopausal breast cancer combined, physical activity was associated with a modest (15-20%) decreased risk. Evidence for a dose-response relationship was observed in approximately half of the higher-quality studies that reported a decreased risk. A trend analysis indicated a 6% (95% confidence interval = 3% to 8%) decrease in breast cancer risk for each additional hour of physical activity per week assuming that the level of activity would be sustained.

CONCLUSIONS

There is evidence for an inverse association between physical activity and breast cancer risk. The evidence is stronger for postmenopausal breast cancer than for premenopausal breast cancer.

Exposure-measurement error is frequently ignored when interpreting epidemiologic study results

INTRODUCTION

One important source of error in study results is error in measuring exposures. When interpreting study results, one should consider the impact that exposure-measurement error (EME) might have had on study results.

METHODS

To assess how often this consideration is made and the form it takes, journal articles were randomly sampled from original articles appearing in the American Journal of Epidemiology and Epidemiology in 2001, and the International Journal of Epidemiology between December 2000 and October 2001.

RESULTS

Twenty-two (39%) of the 57 articles surveyed mentioned nothing about EME. Of the 35 articles that mentioned something about EME, 16 articles described qualitatively the effect EME could have had on study results. Only one study quantified the impact of EME on study results; the investigators used a sensitivity analysis. Few authors discussed the measurement error in their study in any detail.

CONCLUSIONS

Overall, the potential impact of EME on error in epidemiologic study results appears to be ignored frequently in practice.

Physical Activity and Breast Cancer Risk: The European Prospective Investigation into Cancer and Nutrition

There is convincing evidence for a decreased risk of breast cancer with increased physical activity. Uncertainties remain, however, about the role of different types of physical activity on breast cancer risk and the potential effect modification for these associations. We used data from 218,169 premenopausal and postmenopausal women from nine European countries, ages 20 to 80 years at study entry into the European Prospective Investigation into Cancer and Nutrition. Hazard ratios (HR) from multivariate Cox regression models were calculated using metabolic equivalent value-based physical activity variables categorized in quartiles, adjusted for age, study center, education, body mass index, smoking, alcohol use, age at menarche, age at first pregnancy, parity, current oral contraceptive use, and hormone replacement therapy use. The physical activity assessment included recreational, household, and occupational activities. A total physical activity index was estimated based on cross-tabulation of these separate types of activity. During 6.4 years of follow-up, 3,423 incident invasive breast cancers were identified. Overall, increasing total physical activity was associated with a reduction in breast cancer risk among postmenopausal women (P(trend) = 0.06). Specifically, household activity was associated with a significantly reduced risk in postmenopausal (HR, 0.81; 95% confidence interval, 0.70-0.93, highest versus the lowest quartile; P(trend) = 0.001) and premenopausal (HR, 0.71; 95% confidence interval, 0.55-0.90, highest versus lowest quartile; P(trend) = 0.003) women. Occupational activity and recreational activity were not significantly related to breast cancer risk in both premenopausal and postmenopausal women. This study provides additional evidence for a protective effect of physical activity on breast cancer risk.

Physical activity and lung cancer risk in the European Prospective Investigation into Cancer and Nutrition Cohort

Research conducted predominantly in male populations on physical activity and lung cancer has yielded inconsistent results. We examined this relationship among 416,277 men and women from the European Prospective Investigation into Cancer and Nutrition (EPIC). Detailed information on recent recreational, household and occupational physical activity, smoking habits and diet was assessed at baseline between 1992 and 2000. Relative risks (RR) were estimated using Cox regression. During 6.3 years of follow-up we identified 607 men and 476 women with incident lung cancer. We did not observe an inverse association between recent occupational, recreational or household physical activity and lung cancer risk in either males or females. However, we found some reduction in lung cancer risk associated with sports in males (adjusted RR = 0.71; 95% confidence interval 0.50-0.98; highest tertile vs. inactive group), cycling (RR = 0.73; 0.54-0.99) in females and non-occupational vigorous physical activity. For occupational physical activity, lung cancer risk was increased for unemployed men (adjusted RR = 1.57; 1.20-2.05) and men with standing occupations (RR = 1.35; 1.02-1.79) compared with sitting professions. There was no evidence of heterogeneity of physical activity associations across countries, or across any of the considered cofactors. For some histologic subtypes suggestive sex-specific reductions, limited by subgroup sizes, were observed, especially with vigorous physical activity. In total, our study shows no consistent protective associations of physical activity with lung cancer risk. It can be assumed that the elevated risks found for occupational physical activity are not produced mechanistically by physical activity itself but rather reflect exposure to occupation-related lung cancer risk factors.

Reliability and validity of the Past Year Total Physical Activity Questionnaire

The authors determined the validity and reliability of their Past Year Total Physical Activity Questionnaire (PYTPAQ), which assesses the frequency, duration, and intensity of occupational, household, and recreational activities performed over the past year. The PYTPAQ was completed twice at baseline, 9 weeks apart (on average), by 154 healthy Canadian men and women aged 35-65 years for assessment of reliability. The PYTPAQ was completed again 1 year later as a self-administered questionnaire. Four times during the year, participants wore an accelerometer for 7 days and completed 7-day physical activity logs. The authors assessed validity by comparing PYTPAQ summary values with 1-year averages of the physical activity logs and accelerometer data and with physical fitness and anthropometric data measured at baseline and 1 year. Spearman correlations for reliability (metabolic equivalent-hours/week) were 0.64 for total activity, 0.70 for occupational activity, 0.73 for recreational activity, and 0.65 for household activity. For total activity, the intraclass correlation coefficient for correlation between the PYTPAQ and the 7-day physical activity logs was 0.42 (95% confidence interval: 0.28, 0.54), and for the accelerometer data it was 0.18 (95% confidence interval: 0.03, 0.32). Spearman correlations between PYTPAQ hours/week of vigorous activity and maximal oxygen uptake were 0.37 and 0.32 at baseline and follow-up, respectively. In general, the PYTPAQ has acceptable reliability and validity for measurement of past-year physical activity that is comparable to that of similar questionnaires.

Breast cancer and dietary factors in Taiwanese women

OBJECTIVES

To examine the effect of the consumption of dietary factors on the risk of breast cancer in a case-control study in Taiwan.

METHODS

Two-hundred-and-fifty cases and 219 age-matched controls between the ages of 25 and 74 were interviewed in person between 1996 and 1999. Usual consumption of dietary habits including 100 foods was assessed using a food frequency questionnaire and a nutrient database developed and validated in Taiwanese populations.

RESULTS

Cases consumed significantly more fat than controls. Cases also consumed statistically significant less supplements such as vitamins and mineral than controls. Food group analyses showed that highest quartile of beef and pork intake significantly increased risk in younger women (OR = 2.5, 95% CI = 1.0-6.0) and all women (OR = 2.5, 95% CI = 1.1-3.3). The age- education- and total calorie-adjusted odds ratio (OR) of breast cancer risk comparing the highest and second highest quartile of fat intake to the lowest quartile was 5.1, 95% confidence interval (CI): 2.1-13 and 3.5, 95% CI: 1.4-8.7 among those younger cases (< or =40). A multiple regression model indicates a protective effect of supplements (OR: 0.40, 95% CI: 0.3-07) and a harmful effect of dietary fat (OR: 2.6, 95% CI: 1.4-5.0) for the highest versus lowest quartile in all women.

CONCLUSIONS

Our results indicate a strong protective effect of dietary supplements and a harmful effect of dietary fats on the risk of breast cancer among women in Taiwan. These findings should be confirmed in future follow-up studies. Specific amount of dietary supplements and dietary fats should be quantified for a more accurate evaluation on the risk for breast cancer in this population.

Effects of a School-based Obesity-prevention Intervention on Menarche (United States)

OBJECTIVE

Early menarche is a risk factor for breast cancer. Since body composition influences age at menarche we decided to estimate the effects of a school-based intervention for the prevention of obesity on the initiation of menses in young girls.

METHODS

Ten schools were randomized to a modified curriculum or no curricular changes for 2 school-years. Data of 508 pre-menarcheal girls at baseline (age range: 10-13 years) were analyzed.

RESULTS

Girls attending an intervention school experienced menarche less frequently than girls attending control schools during the intervention period (intervention schools = 54%, control schools = 59%; RR = 0.76; 95% CI [0.66, 0.87]). Attending an intervention school was also associated with lower increase in BMI (-0.3 kg/m2; p = 0.003), lower gains in triceps skinfold thickness (-1.5 mm; p = 0.007), decreased television viewing (-0.6 h/day; p<0.0001) and increased physical activity (3.1 MET-h/week; p = 0.032). Including these changes as predictors of menarche incidence attenuated the intervention effect (RR = 0.94; 95% CI [0.80, 1.10]).

CONCLUSIONS

The intervention delayed menarche in this group of girls. The delay was produced by increased physical activity, reduced television viewing and changes in BMI and fat distribution. These findings may have implications for the primary prevention of breast cancer.

Physical activity and risk of endometrial cancer: a report from the Shanghai endometrial cancer study

We evaluated the type and amount of physical activity associated with risk of endometrial cancer. In this population-based case-control study, in-person interviews were completed among 832 incident endometrial cancer cases and 846 age-matched controls. Physical activity from exercise, household activities, and transportation was assessed in adolescence and adulthood, as was lifetime occupational activity. Logistic regression was used to estimate adjusted odds ratios (OR) and 95% confidence limits (95% CL). Women reporting exercise participation in both adolescence and adulthood were at nearly a 40% reduced risk (OR, 0.63; 95% CL, 0.42-0.95), compared with women reporting no exercise in either life period. Postmenopausal women who initiated exercise in adulthood were also at reduced risk (OR, 0.76; 95% CL, 0.56-1.02). Reductions in risk were also observed for common lifestyle activities, including household activity (both life periods) and walking for transportation (adulthood). Examination of the independent and combined effect of exercise and lifestyle activities revealed that women with less active lifestyles but who reported exercise were at 35% reduced risk (OR, 0.65; 95% CL, 0.41-1.02), whereas nonexercisers with more active lifestyles were at 40% to 45% reduced risk. These findings suggest that both lifestyle activities of lower intensity (e.g., walking and doing household chores) and intentional exercise can reduce endometrial cancer risk.

Influence of exercise activity on quality of life in long-term breast cancer survivors

BACKGROUND

Behavioral and lifestyle factors may influence quality of life (QOL) outcomes in breast cancer survivors.

METHODS

Information on QOL (Short Form-36, SF-36), lifestyle and survivorship was collected during telephone interviews with 374 breast cancer patients, diagnosed between 1983 and 1988 at ages 40 years or younger and interviewed, on average 13.2 years following diagnosis. These women previously participated in a case-control study soon after their diagnoses, providing information on breast cancer risk factors including exercise activity. We examined the impact of changes in exercise activity (comparing pre- to post-diagnosis levels) on the SF-36 mental and physical health summary scales using regression analyses.

RESULTS

A positive change in exercise activity was associated with a higher score on the SF-36 physical health summary scale at follow-up (p = 0.005). Change in exercise activity was not associated with the SF-36 mental health summary scale score. Patients who increased their activity levels did not differ from those who did not in terms of medical or demographic characteristics.

CONCLUSION

This study provides one of the longest follow-up periods of breast cancer survivors to date among studies that focus on QOL and is unique in its focus on women diagnosed at a young age. Our results confirm high levels of functioning and well-being among long-term survivors and indicate that women whose exercise activity increased following diagnosis score higher on the SF-36 physical health summary scale. These findings suggest a potential role for exercise activity in maintaining well-being after a cancer diagnosis.

Facteurs de risque du cancer du sein

Because of its increasing incidence, breast cancer is a significant burden for women worldwide. In industrialized countries, breast cancer is the second-leading cause of cancer-related deaths among women, and it is estimated that 1 in every 8 women will develop the disease during her lifetime. Sufficient evidence indicates that a number of genetic, environmental and lifestyle risk exposures during life may play important roles in the etiology of this disease. The purpose of this paper is to review some etiologic factors and underlying mechanisms in relation to breast cancer risk. Based on the published literature, there is sufficient evidence that some established factors are associated with breast cancer risk. Age, early age at menarche, late menopause, height, post-menopausal obesity, family history of breast cancer, ionizing radiation, oral contraceptives, hormonal replacement therapy, mammographic density, some gene mutations and clinical conditions, such as benign breast disease, are associated with an increased risk of breast cancer. The risk decreases with early childbearing, high parity and physical activity, and breastfeeding. Alcohol increases the risk, while caloric restriction may confer protection from breast cancer. Epidemiological evidence for other nutritional factors is insufficient. These results suggest that breast cancer is a multifactorial disease where genetic susceptibility, environment, nutrition and other lifestyle risk factors interact. Better identification of modifiable risk factors and risk reduction of breast cancer may allow implementation of useful strategies for prevention.