Incidence of breast cancer in Chinese women exposed to the 1959-1961 great Chinese famine

Famine Exposure during Early Life and Risk of Cancer in Adulthood: A Systematic Review and Meta-Analysis

OBJECTIVES

Emerging evidences have explored the association between famine exposure during early life and cancer risk in adulthood, but the results remain controversial and inconsistent. This study aimed to provide a comprehensive evidence on the relation of famine exposure to later cancer risk.

DESIGN

Systematic review and meta-analysis.

METHODS

Relevant reports published up to March, 2022 were identified by searching PubMed, Embase, Web of sciences and Medline databases. Pooled relative ratios (RRs) with 95% confidence intervals (CIs) were used to evaluate the effect famine exposure on cancer risk.

RESULTS

Totally, 18 published articles with 6,061,147 subjects were included in this study. Compared with unexposed group, early life famine exposure dramatically increased the risk of cancer in adulthood (RR=1.13, 95% CI: 1.04-1.22). The pooled RRs were different in terms of sex, exposure severity, exposure period, famine type, study design type and cancer location. A remarkably elevated risk for cancer was discerned in women exposed to famine (RR=1.09, 95% CI: 1.00-1.18), severe exposure (RR=1.12, 95% CI: 1.02-1.22) and adolescence exposure (RR=1.76, 95% CI: 1.02-2.50), Chinese famine exposure (RR=1.55, 95% CI: 1.29-1.82) and cohort studies (RR=1.28, 95% CI: 1.13-1.42). Moreover, a significant association of early-life famine exposure with increased risk of breast (RR=1.16, 95% CI: 1.05-1.27) and stomach cancers (RR=1.89, 95% CI: 1.24-2.54) was observed.

CONCLUSION

This meta-analysis suggests that exposure to famine during early life may increase the risk of cancer in adulthood. The above-mentioned association is pronounced in women exposed to famine, severe exposure, adolescence exposure, Chinese famine, cohort studies, breast and stomach cancers. It is essential for decision-makers to take targeted measures for improving population awareness regarding the long-term effect of early life nutritional status.

In utero and childhood exposure to the Great Chinese Famine and risk of cancer in adulthood: the Kailuan Study

BACKGROUND

The risk of cancer in adulthood can be influenced by exposure to environmental factors (e.g., food shortage and stress) in early life.

OBJECTIVES

This study compared the risk of cancer morbidity and mortality between Chinese adults who were or were not exposed to the Great Chinese Famine (1959-1961) in utero or during early childhood.

METHODS

The Kailuan Study participants (n = 101,095) were classified into 5 famine exposure groups by birth year collected at study baseline (2006-2007): after 1961 (unexposed), 1959-1961 (in utero exposed), 1956-1958 (infancy and early childhood exposed, aged 0.1-2.9 y), 1953-1955 (childhood exposed, aged 3.0-5.9 y), and before 1953 (exposed, aged 6+ y). They were further classified by the severity of famine exposure. Cancer and cancer mortality cases from 2006 to 2016 were confirmed by reviewing medical records. Cox proportional hazard models were computed, adjusting for sex, socioeconomic status, and other time-varying cancer-related covariates.

RESULTS

During a median follow-up of 10.0 y, we identified 3560 incident cancer cases and 1749 cancer deaths. Famine exposure at all ages was positively associated with the risk of cancer morbidity and mortality (P < 0.001 for all, compared with unexposed). Severe exposure to famine in early childhood, but not other ages, had a higher risk of composite cancer events [adjusted HR = 2.04 (95% CI: 1.47, 2.84) for 0.1-2.9 y; and 1.61 (95% CI: 1.15, 2.25) for 3.0-5.9 y], relative to the less severely exposed groups of the same age range. When cancer morbidity and mortality were studied separately, similar patterns were observed.

CONCLUSIONS

In utero and early childhood exposures to famine, especially severe famine, were associated with a higher risk of cancer morbidity and mortality in adulthood. Awareness should be raised regarding the long-term effect of early life nutritional status.Trial registration number: ChiCTR-TNRC-11001489 (http://www.chictr.org.cn/showprojen.aspx?proj=8050).

The changing face of hunger: from fasting to the concept of atherogenesis

The history of hunger is a story about natural disasters and wars, but, on the other hand, also about the investigation of evolutionary defense mechanisms concerning quantitative food shortages. The article presents how fasting and the experimental starving oriented the development of physiology, and it is based on a comparative analysis of monographs and articles on starvation in the medical context from library collections and the PubMed database. Over the centuries, doctors have believed that fasting has a beneficial effect on health, and they recommended a restrictive diet during an illness. In the 19th century, the growth of modern physiology was determined by experimental fasting of human subjects and animals. Furthermore, undernourishment and chronic hunger in large populations were recognized as a threat to public health for the first time. During both world wars, depriving civilians of food became a strategy of combat and a method of genocide. The mass nature of war hunger motivated doctors to research the pathophysiology of starvation and refeeding of emaciated people, even in the ghetto or concentration camps. After the Second World War, the invention of the scanning electron microscope enabled systematic studies on the effects of starvation on the human body. As a result, the pathogenesis of atherosclerosis and the cellular metabolism of cholesterol at the submolecular level were clarified. At the turn of the 21st century, the research on the metabolic response to starvation shed new light on atherogenesis and the link between lipid and carbohydrate metabolism.

MicroRNA-4500 Inhibits Migration, Invasion, and Angiogenesis of Breast Cancer Cells via RRM2-Dependent MAPK Signaling Pathway

With the consideration of the dynamic role of microRNAs (miRNAs) in breast cancer, miRNAs may serve as therapeutic targets, helping to prevent development of therapy resistance, maintain stable disease, and prohibit metastatic spread. We identified the differentially expressed breast cancer-related gene ribonucleotide reductase subunit M2 (RRM2) as the study focus through microarray expression profiles. Next, the upstream regulatory microRNA (miR)-4500 of RRM2 was predicted using bioinformatics website analysis, and their binding was verified by a dual luciferase reporter gene assay. The regulatory effects of miR-4500 on breast cancer cell proliferation, apoptosis, migration, invasion, and capillary-like tube formation of endothelial cells were assessed by gain- and loss-of-function experiments. The experimental data revealed that miR-4500 was downregulated, whereas RRM2 was upregulated in breast cancer cells. Mechanistic analysis revealed that miR-4500 downregulated the RRM2 expression to inactivate the mitogen-activated protein kinase (MAPK) signaling pathway. Furthermore, miR-4500 exerted anti-tumor effects by targeting RRM2 through suppression of the MAPK signaling pathway in vitro, evidenced by attenuated cancer cell migration and invasion and capillary-like tube formation of endothelial cells. The in vivo experiments further corroborated in vitro results. Collectively, overexpressed miR-4500 could downregulate RRM2 and inhibit activation of the MAPK signaling pathway, thus attenuating breast cancer cell proliferation, invasion, migration, and angiogenesis and promoting breast cancer cell apoptosis.

Epigenetic Biomarkers for Environmental Exposures and Personalized Breast Cancer Prevention

Environmental and lifestyle factors are believed to account for >80% of breast cancers; however, it is not well understood how and when these factors affect risk and which exposed individuals will actually develop the disease. While alcohol consumption, obesity, and hormone therapy are some known risk factors for breast cancer, other exposures associated with breast cancer risk have not yet been identified or well characterized. In this paper, it is proposed that the identification of blood epigenetic markers for personal, in utero, and ancestral environmental exposures can help researchers better understand known and potential relationships between exposures and breast cancer risk and may enable personalized prevention strategies.

Cancer risk in Chinese diabetes patients: a retrospective cohort study based on management data

The excess risk of cancer observed in patients with type 2 diabetes (T2DM) may have been influenced by detection bias. The aim of this study was to examine the real association by evaluating time-varying site-specific cancer risks in newly diagnosed T2DM patients. A total of 51,324 registered cancer-free individuals newly diagnosed with T2DM between 2004 and 2014 were linked with the Shanghai Cancer Registry and the Vital Statistics through September 2015. A total of 2920 primary, invasive cancer cases were identified during 325,354 person-years period. Within 1 year following diabetes onset, participants with T2DM had higher risks of total, lung and rectal cancer in men and total, liver, pancreas, thyroid, breast and uteri cancer in women. Thereafter the incidence for overall cancer decreased and then increased along with follow-up time, with the upward trend varying by cancer, suggesting potential detection bias. After the initial 1-year period, standardized incidence ratios (SIR) and 95% CIs for overall cancer were 0.80 (95% CI 0.76-0.85) in men and 0.93 (95% CI 0.88-0.99) in women, but a higher risk of breast and thyroid cancers were observed in women, with SIR and 95% CI being 1.13 (1.01, 1.28) and 1.37 (1.11, 1.63), respectively. Our results suggest that T2DM patients are at higher risk of certain cancers; this risk particularly increases shortly after diabetes diagnosis, which is likely to be due to detection bias caused by increased ascertainment. Prevention of female breast and thyroid cancers should be paid attention in Chinese individuals with T2DM.