Mendelian randomization does not support serum calcium in prostate cancer risk

Micronutrients and risks of three main urologic cancers: A mendelian randomization study

Background

The effect of micronutrients on urologic cancers has been explored in observational studies. We conducted the two-sample mendelian randomization (TSMR) study to investigate whether micronutrients could causally influence the risk of urologic cancers.

Methods

Summary statistics for four micronutrients and three main urologic cancers outcomes were obtained from genome-wide association studies (GWAS). MR analyses were applied to explore the potential causal association between them. Sensitivity analyses using multiple methods were also conducted.

Results

Genetically predicted one SD increase in serum copper and iron concentrations was causally associated with increased risks of renal cell carcinoma (RCC) (OR = 3.021, 95%CI = 2.204-4.687, P < 0.001, male; OR = 2.231, 95%CI = 1.524-3.953, P < 0.001, female; OR = 1.595, 95%CI = 1.310-1.758, P = 0.0238, male; OR = 1.484, 95%CI = 1.197-2.337, P = 0.0210, female, respectively) and per SD increase in serum zinc levels was related to decreased risks of RCC (OR = 0.131, 95%CI = 0.0159-0.208, P < 0.001, male; OR = 0.124, 95%CI = 0.0434-0.356, P < 0.001, female). No significant results were observed between micronutrients and the risk of bladder cancer after Bonferroni correction. Additionally, per SD increase in serum zinc level was associated with a 5.8% higher risk of prostate cancer (PCa) [OR = 1.058, 95%CI = 1.002-1.116, P = 0.0403, inverse-variance weight (IVW)].

Conclusions

Micronutrients play a vital role in the development of urological tumors. Future studies are required to replicate the findings, explore the underlying mechanisms, and examine the preventive or therapeutic role of micronutrients in clinical settings.

[Essential trace elements, vitamins, and selected electrolytes in complementary medicine for cancer patients]

OBJECTIVE

Are there any evidence-based medicine (EBM)-supported treatment approaches of complementary and alternative medicine (CAM) methods for urological oncologists?

METHODS

We reviewed the actual German S3 guidelines "Supportive Care" and "Complementary Medicine" as well as the online-tool Onkopedia for recommendations about essential trace elements (Zn, Se, Mn, Fe), vitamins (A, B, C, D, E), and electrolytes (Mg, Ca). Furthermore, we added results of randomized trials to present potential future developments.

RESULTS

Each therapy with micronutrients should be based on laboratory observation of a deficit. There are selected guideline recommendations for selenium, iron and vitamin D. Potential indications were registered for manganese, vitamin A derivates, and vitamin C. No benefit was observed for vitamin B, zinc, and vitamin E.

CONCLUSION

Micronutrients should be substituted in the case of deficit. General supplementation of daily nutrition is not recommended for cancer patients.

Systematic review of Mendelian randomization studies on risk of cancer

BACKGROUND

We aimed to map and describe the current state of Mendelian randomization (MR) literature on cancer risk and to identify associations supported by robust evidence.

METHODS

We searched PubMed and Scopus up to 06/10/2020 for MR studies investigating the association of any genetically predicted risk factor with cancer risk. We categorized the reported associations based on a priori designed levels of evidence supporting a causal association into four categories, namely robust, probable, suggestive, and insufficient, based on the significance and concordance of the main MR analysis results and at least one of the MR-Egger, weighed median, MRPRESSO, and multivariable MR analyses. Associations not presenting any of the aforementioned sensitivity analyses were not graded.

RESULTS

We included 190 publications reporting on 4667 MR analyses. Most analyses (3200; 68.6%) were not accompanied by any of the assessed sensitivity analyses. Of the 1467 evaluable analyses, 87 (5.9%) were supported by robust, 275 (18.7%) by probable, and 89 (6.1%) by suggestive evidence. The most prominent robust associations were observed for anthropometric indices with risk of breast, kidney, and endometrial cancers; circulating telomere length with risk of kidney, lung, osteosarcoma, skin, thyroid, and hematological cancers; sex steroid hormones and risk of breast and endometrial cancer; and lipids with risk of breast, endometrial, and ovarian cancer.

CONCLUSIONS

Despite the large amount of research on genetically predicted risk factors for cancer risk, limited associations are supported by robust evidence for causality. Most associations did not present a MR sensitivity analysis and were thus non-evaluable. Future research should focus on more thorough assessment of sensitivity MR analyses and on more transparent reporting.

Health Effects of Calcium: Evidence From Mendelian Randomization Studies

Calcium is widely used in conjunction with vitamin D to prevent osteoporosis. The use of calcium supplementation is also promoted for its potential benefits in lowering the risk for metabolic syndromes and cancers. However, the causal link between calcium and various health outcomes remains unclear. This review focuses on the evidence from 24 Mendelian randomization (MR) studies that were designed to minimize bias from confounding and reverse causation. These MR studies evaluated the effect of lifelong genetically higher serum calcium levels on various health outcomes. Overall, available MR studies found no conclusive effects of serum calcium levels on bone mineral density and fracture, ischemic stroke and heart failure, cancers, type 2 diabetes, Parkinson disease, or offspring birth weight. However, a higher serum calcium concentration was reported to have estimated causal effects on increased risks for coronary artery disease (especially myocardial infarction), migraine, renal colic, allergy/adverse effect of penicillin, and reduced risks for osteoarthrosis and osteoarthritis. In conclusion, supplementation of calcium in individuals from the general population is not predicted to influence the risk of most investigated diseases to date. Moreover, long-term high serum calcium concentrations may result in adverse health outcomes. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Title Changes in the Mineral Composition of Rat Femoral Bones Induced by Implantation of LNCaP Prostate Cancer Cells and Dietary Supplementation

Prostate cancer (PCa) is the second most frequent cancer in men and the fifth most common cause of death worldwide, with an estimated 378,553 deaths in 2020. Prostate cancer shows a strong tendency to form metastatic foci in the bones. A number of interactions between cancer cells attacking bones and cells of the bone matrix lead to destruction of the bone and growth of the tumour. The last few decades have seen increased interest in the precise role of minerals in human health and disease. Tumour cells accumulate various minerals that promote their intensive growth. Bone, as a storehouse of elements, can be a valuable source of them for the growing tumour. There are also reports suggesting that the presence of some tumours, e.g., of the breast, can adversely affect bone structure even in the absence of metastasis to this organ. This paper presents the effect of chronic dietary intake of calcium, iron and zinc, administered in doses corresponding maximally to twice their level in a standard diet, on homeostasis of selected elements (Ca, K, Zn, Fe, Cu, Sr, Ni, Co, Mn and Mo) in the femoral bones of healthy rats and rats with implanted cancer cells of the LNCaP line. The experiment was conducted over 90 days. After the adaptation period, the animals were randomly divided into four dietary groups: standard diet and supplementation with Zn, Fe and Ca. Every dietary group was divided into experimental group (with implanted cancer cells) and control group (without implanted cancer cells). The cancer cells (LnCaP) were implanted intraperitoneally in the amount 1 × 106 to the rats at day 90 of their lifetime. Bone tissue was dried and treated with microwave-assisted mineral digestation. Total elemental content was quantified by ICP-MS. Student's t-test and Anova or Kruskal-Wallis tests were applied in order to compare treatment and dietary groups. In the case of most of the diets, especially the standard diet, the femoral bones of rats with implanted LNCaP cells showed a clear downward trend in the content of the elements tested, which may be indicative of slow osteolysis taking place in the bone tissue. In the group of rats receiving the standard diet, there were significant reductions in the content of Mo (by 83%), Ca (25%), Co (22%), Mn (13%), K (13%) and Sr (9%) in the bone tissue of rats with implanted LNCaP cells in comparison with the control group receiving the same diet but without LNCaP implantation. Supplementation of the rat diet with calcium, zinc and iron decreased the frequency of these changes relative to the standard diet, which may indicate that the diet had an inhibitory effect on bone resorption in conditions of LNCaP implantation. The principal component analysis (PCA) score plot confirms the pronounced effect of implanted LNCaP cells and the standard diet on bone composition. At the same time, supplementation with calcium, zinc and iron seems to improve bone composition. The microelements that most often underwent quantitative changes in the experimental conditions were cobalt, manganese and molybdenum.

Examination of potential novel biochemical factors in relation to prostate cancer incidence and mortality in UK Biobank

BACKGROUND

Although prostate cancer is a leading cause of cancer death, its aetiology is not well understood. We aimed to identify novel biochemical factors for prostate cancer incidence and mortality in UK Biobank.

METHODS

A range of cardiovascular, bone, joint, diabetes, renal and liver-related biomarkers were measured in baseline blood samples collected from up to 211,754 men at recruitment and in a subsample 5 years later. Participants were followed-up via linkage to health administrative datasets to identify prostate cancer cases. Hazard ratios (HRs) and 95% confidence intervals were calculated using multivariable-adjusted Cox regression corrected for regression dilution bias. Multiple testing was accounted for by using a false discovery rate controlling procedure.

RESULTS

After an average follow-up of 6.9 years, 5763 prostate cancer cases and 331 prostate cancer deaths were ascertained. Prostate cancer incidence was positively associated with circulating vitamin D, urea and phosphate concentrations and inversely associated with glucose, total protein and aspartate aminotransferase. Phosphate and cystatin-C were the only biomarkers positively and inversely, respectively, associated with risk in analyses excluding the first 4 years of follow-up. There was little evidence of associations with prostate cancer death.

CONCLUSION

We found novel associations of several biomarkers with prostate cancer incidence. Future research will examine associations by tumour characteristics.