Latest Research News on Cancer Risk: Dec 2020
Endogenous hormones and breast cancer risk.
There is substantial evidence that high estrogen levels in postmenopausal women are associated with an increase in breast cancer risk, but such a relation has not yet been established in premenopausal women, despite biologic evidence that breast epithelial cell division rates are high during the luteal phase of the menstrual cycle when estradiol and progesterone levels are high. The lack of total consistency among studies that have assessed estrogen differences, whether in breast cancer patients versus controls or in subgroups of the population characterized by different risk profiles for breast cancer, is not unexpected given the extraordinarily complex methodological issues that must be addressed in these studies. There has been a clear evolution over time in the level of sophistication of these types of studies, further decreasing the likelihood of finding consistent patterns in the literature. Other hormones may play an important role in breast cancer development as well. Experimental data are particularly compelling for a role of progesterone and prolactin, but hormonal studies in women are not entirely convincing regarding the role of these two hormones, nor is the literature nearly as extensive as it is for the estrogens. Studies of various androgens are even less consistent. Moreover, such studies suffer from a lack of precise hypotheses regarding how these hormones might directly alter risk. 
Systematic Population-Based Assessment of Cancer Risk in First-Degree Relatives of Cancer Probands
Cancer has long been recognized to have a familial component. Elevated risks for cancers at the same site for relatives of cancer probands have been reported for both common cancers and a number of the rarer cancer sites. For a particular cancer site, however, the estimated risks to relatives have varied considerably depending on criteria for selection of probands, how cancers were determined in relatives, and overall study design. Not surprisingly, the estimated risks of other cancers in relatives of probands with cancer at a given site have been subject to even more variation.
The aim of this study was to use the Utah Population Database resource to systematically study familial clustering of 28 distinct cancer site definitions among first-degree relatives (parents, siblings, and offspring) of cancer probands.
We estimated familial relative risks from the Utah Population Database by identifying all cases of cancer in these first-degree relatives. These observed values were compared with those expected based on cohort-specific internal rates calculated from 399 786 relatives of all individuals in the Utah Population Database known to have died in Utah.
All sites showed an excess of cancers of the same site among relatives, with thyroid and colon cancers and lymphocytic leukemia showing the highest familial risks. When the analyses were restricted to cases with early ages at diagnosis, increased familial components for most cancer sites became evident. A significant difference in familial relative risk (FRR) between male (FRR = 4.04; 95% confidence interval [CI] = 3.13−5.07) and female (FRR = 2.24; 95% CI = 1.54−3.08) probands was found for colon cancer. Highly significant familial associations (one-sided; p <0l) were found among breast, colon, and prostate cancers and between breast and thyroid cancers. Statistically significant (one-sided, P <.01) associations were also found between tobacco-associated sites (lung, larynx, lip, and cervix).
This study represents a unique comprehensive population-based study of familial cancer. The familial associations reported here will be useful in generating hypotheses about specific genetic and environmental factors that can be tested in genetic linkage and case-control studies. 
Dietary effects on breast-cancer risk in Singapore
It is suspected that diet influences the risk of getting breast cancer. A study of diet and breast cancer was done among 200 Singapore Chinese women with histologically confirmed disease and 420 matched controls. A quantitative food-frequency questionnaire was used to assess intakes of selected nutrients and foods 1 year before interview. Daily intakes were computed and risk analysed after adjustment for concomitant risk factors. In premenopausal women, high intakes of animal proteins and red meat were associated with increased risk. Decreased risk was associated with high intakes of polyunsaturated fatty acids (PUFA), beta-carotene, soya proteins, total soya products, a high PUFA to saturated fatty acid ratio, and a high proportion of soya to total protein. In multiple analysis, the variables which were significant after adjustment for each other were red meat (p < 0·001) as a predisposing factor, and PUFA (p=0·02), beta-carotene (p=0·003), and soya protein (p=0·02) as protective factors. The analysis of dietary variables in postmenopausal women gave uniformly non-significant results. Our finding that soya products may protect against breast cancer in younger women is of interest since these foods are rich in phyto-oestrogens 
Oxidative Stress and Antioxidant Status in Nigerian E-waste Workers: A Cancer Risk Predictive Study
Introduction: In Africa, Nigeria has been reported as the largest destination for unregulated volume of electronic waste (e-waste). Currently, e-waste management practices in Nigeria remain completely primitive, taking place essentially in the informal sector. Recent report indicates that the majority (88.8%) of Nigerian e-waste workers have exposure burden of ≥6 hours per day; ≥6 days per week, and reportedly worked without personal protective devices. These crude management practices enhance the workers’ exposure to electronic waste borne toxic and carcinogenic metals and chemicals through almost all body cavities.
Objective: Concisely, this study aimed at evaluating the status of enzymatic and non-enzymatic oxidative stress biomarkers as cancer risk indices in Nigerians occupationally exposed to e-waste.
Methods: Serum levels of malondialdehyde (MDA), uric acid (UA), albumin (ALB), total bilirubin (TBil) and conjugated bilirubin (Cbil.)] and activities of enzymatic antioxidants [glutathione reductase (Gr), catalase (Cat), superoxide dismutase (SOD) and glutathione peroxidase (GPx)] were determined in Nigerian e-waste workers (n=63) and in age-matched unexposed participants (n=41), using standard colorimetric methods.
Results: Significantly elevated lipid peroxidation and raised uric acid levels were indicated in e-waste workers. Further to this, CAT, SOD and GPx were significantly reduced in e-waste workers compared with the unexposed human population. Comparatively different observations were not registered in the activity of GR and levels of ALB, TBil. and CBil. between exposed and unexposed participants.
Conclusion: This study provides evidence that the oxidative stress observed in the studied population could be associated with occupational exposure to e-waste chemicals and may be a predictive mechanism for chemical carcinogenesis in Nigerians involved in primitive e-waste management. 
Human Health Risk Assessment of Heavy Metals in Snail (Archachatina marginata) from Four Contaminated Regions in Rivers State, Nigeria
This study assessed the health risks of heavy metals contamination in snail (Archachatina marginata) from crude oil producing regions in Rivers State, Nigeria. Cadmium, lead, chromium, nickel, zinc and manganese concentrations in snail muscle tissue taken from the various regions were detected. The potential non-carcinogenic health risks for consumers were investigated by assessing the Estimated Daily Intake and Target Hazard Quotients. Snail caught in the various sites were more contaminated by cadmium and lead (ranged from 0.50 – 0.65 and 2.60 – 5.00 kg/person/day respectively) than Nickel, Manganese, Zinc and Chromium which were below established reference dose. Target Hazard Quotient values indicate that there is no carcinogenic risk for humans except for lead. Carcinogenic Risk for Nickel (4.1 E-3 – 1.0 E-2) indicate that snail from the study sites may not be safe for human consumption and as such consumers of this have the probability of contracting cancer due to Nickel exposure over a lifetime of 70 years or more in future. 
 Bernstein, L. and Ross, R.K., 1993. Endogenous hormones and breast cancer risk. Epidemiologic reviews, 15(1), pp.48-65.
 Goldgar, D.E., Easton, D.F., Cannon-Albright, L.A. and Skolnick, M.H., 1994. Systematic population-based assessment of cancer risk in first-degree relatives of cancer probands. JNCI: Journal of the National Cancer Institute, 86(21), pp.1600-1608.
 Lee, H.P., Lee, J., Gourley, L., Duffy, S.W., Day, N.E. and Estève, J., 1991. Dietary effects on breast-cancer risk in Singapore. The lancet, 337(8751), pp.1197-1200.
 Igharo, G., Anetor, J. I., Osibanjo, O., Osadolor, H., David, M. and Agu, K. (2015) “Oxidative Stress and Antioxidant Status in Nigerian E-waste Workers: A Cancer Risk Predictive Study”, Journal of Advances in Medicine and Medical Research, 13(2), pp. 1-11. doi: 10.9734/BJMMR/2016/22770.
 C. Onuoha, S., C. Anelo, P. and W. Nkpaa, K. (2015) “Human Health Risk Assessment of Heavy Metals in Snail (Archachatina marginata) from Four Contaminated Regions in Rivers State, Nigeria”, Chemical Science International Journal, 11(2), pp. 1-8. doi: 10.9734/ACSJ/2016/22163.