Calcium intake and colorectal adenoma in a US colorectal cancer early detection program

Spatial and temporal patterns of colorectal cancer in Asia, 1990-2019

BACKGROUND

Asia accounts for the largest burden of colorectal cancer (CRC) worldwide. This study examines the temporal patterns of CRC in Asia in the last three decades.

METHODS

The data pertaining to CRC burden measured by incidence, mortality, and disability-adjusted-life-years (DALYs) and its risk factors for 49 countries in the Asian continent were drawn from the Global Burden of Disease 2019 study between 1990 and 2019. Mortality-to-incidence ratio (MIR) was employed as a proxy indicator of 5-year survival rates.

RESULTS

In Asia, incident cases more than tripled from 270,851 to 1.1 million, deaths tripled from 183,252 to 560,426, and DALYs more than doubled from 5 million to 13.4 million between 1990 and 2019. The age-standardized incidence rate (ASIR) increased from 14.0/100,000 to 23.9/100,000, age-standardized mortality rate (ASMR) increased from 10.1/100,000 to 12.5/100,000, and MIR decreased from 0.68 to 0.50 between 1990 and 2019. ASIR varied 10-folds across countries from 5.6/100,000 in Bangladesh to 62.0/100,000 in Taiwan in 2019 and ASMR from 4.9/1000 in Bangladesh to 30.3/100,000 in Brunei. In 2019, diet low in milk (18.7%) and whole grains (15.2%) and calcium (16.6%) were the major contributory risk factors in CRC DALYs in 2019.

CONCLUSION

CRC is a fast-rising neoplasm in Asia and its burden can be curtailed by focusing on primary prevention (e.g., diet and physical activity) and secondary prevention through screening. The policy focus and resources must be directed towards capacity building, including cancer infrastructure and quality data availability from cancer registries.

Calcium and dairy products in the chemoprevention of colorectal adenomas: a systematic review and meta-analysis

The risk of transition to colorectal cancer (CRC) in advanced colorectal adenomas (ACAs) is about 2.5 times higher than the non-advanced ones. This systematic review and meta-analysis was performed to determine the effect of calcium and dairy products on the incidence of CAs and ACAs. Six databases were systematically searched and 37 relevant clinical trials and observational studies involving over 10,964 cases were selected for inclusion. The results showed that calcium consumption reduced the risk of CAs incidence by 8% (RR: 0.92; 95% CI: 0.89-0.96), and calcium intake as a food and dairy product reduced it about 21% (RR: 0.79; 95% CI: 0.72-0.86), and 12% (RR: 0.88; 95% CI: 0.78-0.98), respectively. However, calcium supplementation did not show a significant effect on CAs incidence (RR: 0.97; 95% CI: 0.89-1.05). Results also revealed that total calcium intake markedly reduced the risk of ACAs (RR: 0.79; 95% CI: 0.73-0.85) and the risk of recurrence of adenomas about 12% (RR: 0.88; 95% CI: 0.84-0.93). Our results suggest that natural sources of calcium such as dairy products and foods may have more effective role than supplementary calcium in terms of reducing the risk of incidence and recurrence of colorectal adenomas and advanced adenomas.

The relationship between the index of nutritional quality and the risk of colorectal cancer and adenoma : a case-control study

OBJECTIVE

Colorectal cancer is one of the most common cancers in the world, whereas dietary factors are its most modifiable risk factors. The index of nutritional quality is considered as a general overview of the nutrient content of diet. The aim of this study is to determine the relationship between the index of nutritional quality and the risk of colorectal cancer and adenomas.

METHODS

Overall, 129 colorectal cancer and 130 colorectal adenoma cases and 240 healthy controls were studied in three major general hospitals in Tehran province, Iran. Index of nutritional quality scores were calculated based on information on the usual diet that was assessed by a valid and reliable Food Frequency Questionnaire. Multivariate logistic regression was used to estimate the relationship between the index of nutritional quality scores and the risk of colorectal cancer and adenoma.

RESULTS

After controlling for several confounding factors, the index of nutritional quality of calcium, vitamin C, riboflavin, folate and fiber were associated with decreased risk of colorectal cancer [ORcalcium: 0.21 (0.08-0.52), ORvitC: 0.16 (0.09-0.28), ORvitB2: 0.35 (0.18-0.65), ORfolate: 0.33 (0.16-0.65), ORfiber: 0.35 (0.21-0.58)]. Also, the inverse association were observed between risk of CRA and the index of nutritional quality of calcium, vitamin C, riboflavin, folate and fiber [OR calcium: 0.32 (0.14-0.74), ORvitC: 0.51 (0.34-0.73), ORvitB2: 0.48 (0.28-0.82), OR folate: 0.44 (0.23-0.81), OR fiber: 0.62 (0.42-0.92)].

CONCLUSION

This study showed that individuals who have a healthier diet, high in calcium, vitamin C, riboflavin, folate and fiber and food groups like fruits, vegetables and whole-grain and less in sweets and red or process meats are at a lower risk of colorectal cancer and CRA than those with unhealthy and poor diet.

Additively protective effects of vitamin D and calcium against colorectal adenoma incidence, malignant transformation and progression: A systematic review and meta-analysis

BACKGROUND

Colorectal cancer (CRC) exhibits a linear progression from normal colonic epithelium, adenoma initiation, carcinoma transformation and even to metastasis. Diet changes might influence carcinogenesis and prognosis. We aimed to determine the effects of vitamin D and calcium on colorectal adenoma incidence, malignancy development and prognosis.

METHODS

Systematic literature searches (PubMed, Embase, and Cochrane Library databases) and hand searches were performed by September 30, 2019. A random-effects model was adopted to pool relative ratios (RRs) for colorectal tumour incidence or hazard ratios (HRs) for CRC mortality. Stratified analyses were performed by gender, tumour location, calcium intake level and ethnic group.

RESULTS

Total 854,195 cases from 166 studies were included. The colorectal adenoma incidence was inversely correlated with the circulating 25-hydroxyvitamin D [25(OH)D] level (RR: 0.80, 95% CI: 0.71-0.89), vitamin D intake (RR: 0.87, 95% CI: 0.82-0.92) and calcium intake (RR: 0.86, 95% CI: 0.81-0.91). The CRC incidence was decreased by circulating 25(OH)D (RR: 0.67, 95% CI: 0.59-0.77), vitamin D intake (RR: 0.85, 95% CI: 0.78-0.93) and calcium intake (RR: 0.75, 95% CI: 0.70-0.79). High-level circulating 25(OH)D triggered better overall survival (HR: 0.67, 95% CI: 0.57-0.79) and CRC-specific survival (HR: 0.63, 95% CI: 0.53-0.74). Stratified analyses showed that vitamin D and calcium significantly suppressed colorectal tumour incidence among women. Left-sided CRC risk was reversely related to circulating 25(OH)D (RR: 0.60, 95% CI: 0.41-0.88) and vitamin D intake (RR: 0.73, 95% CI: 0.57-0.93). Circulating 25(OH)D decreased colorectal adenoma (RR: 0.63, 95% CI: 0.48-0.82) and CRC (RR: 0.69, 95% CI: 0.56-0.86) risk in populations with higher calcium intake. European and American populations benefited more from vitamin D intake against colorectal tumour. A significant dose-response relationship was observed between intake of vitamin D or calcium and colorectal tumour incidence.

CONCLUSIONS

Vitamin D and calcium play additively chemopreventive roles in colorectal adenoma incidence, malignant transformation and progression, especially for women and left-sided CRC patients.

Body mass index, calcium supplementation and risk of colorectal adenomas

Calcium supplementation (1,200 mg/day) did not significantly reduce colorectal adenomas in our recent randomized, controlled trial (Vitamin D/Calcium Polyp Prevention Study, VCPPS, 2004-2013) in contrast to our previous trial (Calcium Polyp Prevention Study, CPPS, 1988-1996). To reconcile these findings, we identified participant characteristics that differed between the study populations and modified the effect of calcium supplementation on adenomas or high-risk findings (advanced or multiple adenomas). Compared to the CPPS, more participants in the VCPPS were obese (body mass index (BMI) ≥30 kg/m² ; 37.5% vs. 24.4%) and fewer had normal BMI (BMI <25 kg/m² ; 18.5% vs. 31%). BMI appeared to modify the effect of calcium supplementation on adenomas and especially on high risk-findings: in the VCPPS, there was a 44% reduction in high-risk findings among individuals whose BMI was normal (RR = 0.56, 95% CI = 0.26-1.23), but not among overweight (RR = 1.09, 95% CI = 0.62-1.91) or obese (RR = 1.54, 95% CI = 0.92-2.57) individuals (p_interaction = 0.03). Similarly, in the CPPS, there was a 56% reduction in high-risk findings among individuals whose BMI was normal (RR = 0.44, 95% CI = 0.26-0.74), but not among overweight (RR = 0.87, 95% CI = 0.55-1.39) or obese (RR = 1.02, 95% CI = 0.57-1.82) individuals (p_interaction = 0.02). Standardization of each trial's findings to the BMI distribution in the other attenuated calcium's protective effect on adenomas in the CPPS but enhanced it in the VCPPS. In conclusion, 1,200 mg/day calcium supplementation may reduce risk of colorectal adenomas among those with normal BMI but not in overweight or obese individuals; and differences in BMI distribution partially account for the apparent difference in calcium efficacy between the two trials.

Vitamins, Are They Safe?

The consumption of a daily multivitamin among people all over the world is dramatically increasing in recent years. Most of the people believe that if vitamins are not effective, at least they are safe. However, the long term health consequences of vitamins consumption are unknown. This study aimed to assess the side effects and possible harmful and detrimental properties of vitamins and to discuss whether vitamins can be used as safe health products or dietary supplements. We performed a MEDLINE/PubMed, EMBASE, Scopus and Google Scholar search and assessed reference lists of the included studies which were published from 1993 through 2015. The studies, with an emphasis on RCTs (randomized controlled clinical trials), were reviewed. As some vitamins such as fat-soluble vitamins (vitamin A, vitamin D, vitamin E), and also some of the water-soluble vitamins like folic acid may cause adverse events and some like vitamin C is widely taken assuming that it has so many benefits and no harm, we included relevant studies with negative or undesired results regarding the effect of these vitamins on health. Our recommendation is that taking high-dose supplements of vitamins A, E, D, C, and folic acid is not always effective for prevention of disease, and it can even be harmful to the health.

Nutrients, foods, and colorectal cancer prevention

Diet has an important role in the development of colorectal cancer. In the past few decades, findings from extensive epidemiologic and experimental investigations have linked consumption of several foods and nutrients to the risk of colorectal neoplasia. Calcium, fiber, milk, and whole grains have been associated with a lower risk of colorectal cancer, and red meat and processed meat have been associated with an increased risk. There is substantial evidence for the potential chemopreventive effects of vitamin D, folate, fruits, and vegetables. Nutrients and foods also may interact, as a dietary pattern, to influence colorectal cancer risk. Diet likely influences colorectal carcinogenesis through several interacting mechanisms. These include the direct effects on immune responsiveness and inflammation, and the indirect effects of overnutrition and obesity-risk factors for colorectal cancer. Emerging evidence also implicates the gut microbiota as an important effector in the relationship between diet and cancer. Dietary modification therefore has the promise of reducing colorectal cancer incidence.

Calcium intake and colorectal adenoma risk: dose-response meta-analysis of prospective observational studies

Evidence from randomized controlled trials suggests that calcium may protect against recurrence of colorectal adenomas, which could lead to the subsequent prevention of cancer. Yet the trials used only a large single dose and were of small sizes, and thus, knowledge of the dose-response relationship and influence on high-risk adenomas is limited. To address these issues, we conducted linear and nonlinear dose-response meta-analyses primarily based on prospective observational studies published up to July 2014 identified from PubMed and Embase. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated for total and supplemental calcium intake, respectively, using a random-effects model. For total calcium intake, summary RR for each 300 mg/day increase was 0.95 (95% CI = 0.92-0.98; I(2)  = 45%; eight studies with 11,005 cases; range of intake = 333-2,229 mg/day). Evidence of nonlinearity was indicated: approximately, compared to 550 mg/day of total calcium intake, the summary RR was 0.92 (95% CI = 0.89-0.94) at 1,000 mg/day and 0.87 (95% CI = 0.84-0.90) at 1,450 mg/day (pnonlinearity  < 0.01). Associations were stronger for high-risk adenomas (≥1 cm in diameter, (tubulo)villous histology, dysplasia, or multiplicity): approximately, compared to 550 mg/day of total calcium intake, the summary RR was 0.77 (95% CI = 0.74-0.81) at 1,000 mg/day and reduced to 0.69 (95% CI = 0.66-0.73) at 1,450 mg/da (pnonlinearity  < 0.01). For supplemental calcium intake, summary RR of total adenoma risk for each 300 mg/day increase was 0.96 (95% CI = 0.93-0.99; I(2)  = 0%; three studies with 4,548 cases; range of supplementation = 0-1,366 mg/day). In conclusion, calcium intake may continue to decrease the risk of adenomas, particularly high-risk adenomas, over a wide range of calcium intake.

Total calcium intake and colorectal adenoma in young women

BACKGROUND

Total calcium intake appears to reduce occurrence of colorectal adenoma; however, the dose necessary for prevention in young women is unclear. We examined fine categories of calcium intake in relation to occurrence of first colorectal adenoma in a cohort of mostly premenopausal (88 %) women aged 26-60 at time of endoscopy.

DESIGN

We conducted an analysis among 41,403 participants in the Nurses' Health Study II and assessed intakes of calcium prior to endoscopy through participants' responses to biannual questionnaires.

RESULTS

Between 1991 and 2007, we documented 2,273 colorectal adenoma cases. There was a significant trend across categories of calcium intakes with lowest intakes suggestive of higher occurrence of adenoma (p = 0.03) and those in the distal colon (p = 0.03) and rectum (p = 0.04). Compared with 1,001-1,250 mg/day of calcium intake, ≤ 500 mg/day was suggestive of a modest increase in occurrence of adenoma (multivariable RR = 1.21, 95 % CI 0.90-1.61); there were also suggestions of an increased risk with >500 to ≤ 700 mg/day of calcium. The association between ≤ 500 mg/day of calcium intake and adenoma was stronger for multiple (RR = 2.27, 95 % CI 1.38, 3.72), large (≥ 1 cm) (RR = 2.01, 95 % CI 1.27, 3.21), and high-risk adenoma (≥ 1 cm or mention of villous histology/high-grade dysplasia) (RR = 1.76, 95 % CI 1.13, 2.72). No differences in associations were noted between jointly categorized calcium and phosphorus or magnesium intakes.

CONCLUSIONS

Our findings suggest that low intakes of calcium, <500 and possibly 500-700 mg/day, in younger women are associated with an increased risk of multiple and advanced colorectal adenoma.

Calcium, dairy and colon cancer - the latest

There is very strong in vitro and observational data showing a protective association between dairy and calcium intake and colorectal cancer. Vitamin D status and possibly genetics also seem to influence this link.

A few RCTs suggest calcium + vit. D supplements help prevent intestinal polyp recurrence. We lack RCT evidence that this in turn stops colon cancer, and if so it is more likely to work in at-risk rather than general populations.

The role of number of meals, coffee intake, salt and type of cookware on colorectal cancer development in the context of the Mediterranean diet

OBJECTIVE

To investigate the association between dietary behaviours and colorectal cancer (CRC) in the context of the Mediterranean diet.

DESIGN

Case-control study.

SETTING

All patients (cases) were recruited from Saint Savvas Cancer Hospital and Alexandra General Hospital in Athens, Greece. Controls were voluntarily selected from the general population and matched to cases by age group (±10 years) and sex.

SUBJECTS

Two hundred and fifty cases with newly diagnosed CRC (mean age 63 (sd 12) years, 59·6 % males) and 250 controls matched on age and sex were studied. A standardized questionnaire assessing sociodemographic, clinical, lifestyle, dietary characteristics and nutritional behaviours was applied. Multiple logistic regression analysis was used to evaluate the aforementioned factors in addition to the MedDietScore (an index that evaluates adherence to the Mediterranean diet) on CRC development.

RESULTS

The higher the daily number of meals, the lower the likelihood of having CRC (OR = 0·74, 95 % CI 0·61, 0·89); coffee drinking was associated with higher likelihood of having CRC (OR = 3·27, 95 % CI 1·09, 9·8); the use of non-stick cookware was positively associated with CRC (OR = 1·57, 95 % CI 1·02, 2·4). However, these associations slightly lost their significance when adherence to the Mediterranean diet was taken into account. Moreover, a 1/75 increase in the modified-MedDietScore plus the aforementioned nutritional behaviours was associated with 13 % lower odds (95 % CI 0·83, 0·91, P < 0·001) of having CRC.

CONCLUSIONS

Nutritional behaviours in addition to dietary habits should be taken into account in detecting individuals prone to the development of CRC.

Colorectal Chemoprevention Pilot Study (SWOG-9041), randomized and placebo controlled: the importance of multiple luminal lesions

BACKGROUND

Colorectal cancer is common worldwide and chemoprevention has the potential of reducing the number of individuals who may suffer and perish from this disease.

METHODS

A randomized placebo controlled pilot study in colorectal cancer patients was performed using calcium carbonate as the test agent in a multi-institutional oncology study group.

RESULTS

Two hundred twenty volunteers were randomized in the study. The primary goals of compliance, accrual, and toxicity monitoring are presented. Presence of multiple adenomas at study entry and subsequent development of metachronous adenomas were recorded and found to be associated with synchronous adenomas. The secondary endpoint of recurrent adenomas indicated lower rates of new adenoma in the volunteers randomized to the calcium group.

CONCLUSION

This pilot study indicates the feasibility of enrolling survivors of colorectal cancer as study volunteers in a colorectal neoplasm chemoprevention clinical trial and oral calcium continues to be a potentially effective drug in reducing colorectal adenomas.

Elemental fingerprinting of tumorous and adjacent non-tumorous tissues from patients with colorectal cancer using ICP-MS, ICP-OES and chemometric analysis

Tumorous and adjacent non-tumorous paired biopsies from 38 patients with colorectal cancer were analyzed by inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectrometry after low-volume microwave digestion. 18 elements were investigated: Ag, Al, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Ni, P, Pb, S, Se and Zn. Different chemometric tools were used for data evaluation: Wilcoxon signed rank test, Hieratical clustering analysis, principal component analysis (PCA) and linear discriminant analysis (LDA). With the exception of Al, tumours were observed to have significantly more elevated concentrations of essential elements as compared to non-tumours. On the contrary, elements considered potentially carcinogenic such as Cr, Ni, Mo or Co do not display significant differences. When PCA was applied, different components were obtained for tumorous and non-tumorous tissues. When LDA was applied for the elements studied (including essential and non-essential elements) about 90% of cases were correctly classified.

The effect of calcium plus vitamin D on risk for invasive cancer: results of the Women's Health Initiative (WHI) calcium plus vitamin D randomized clinical trial

In the Women's Health Initiative (WHI) trial of calcium plus vitamin D (CaD), we examined the treatment effect on incidence and mortality for all invasive cancers. Postmenopausal women (N = 36,282) were randomized to 1,000 mg of elemental calcium with 400 IU vitamin D3 or placebo. Cox models estimated risk of cancer incidence and mortality. After 7.0 yr, 1,306 invasive cancers were diagnosed in the supplement and 1,333 in the placebo group [hazard ratio (HR) = 0.98; CI = 0.90, 1.05, unweighted P = 0.54]. Mortality did not differ between supplement (315, annualized% = .26) and placebo [(347, 0.28%; P = 0.17; HR = 0.90 (0.77, 1.05)]. Significant treatment interactions on incident cancer were found for family history of cancer, personal total intake of vitamin D, smoking, and WHI dietary trial randomized group. Calcium/vitamin D supplementation did not reduce invasive cancer incidence or mortality. Supplementation lowered cancer risk in the WHI healthy diet trial arm and in women without a first-degree relative with cancer. The interactions are only suggestive given multiple testing considerations. The low vitamin D dose provided, limited adherence, and lack of serum 25(OH)D values should be considered when interpreting these findings.

Effects of supplemental vitamin D and calcium on biomarkers of inflammation in colorectal adenoma patients: a randomized, controlled clinical trial

Vitamin D and calcium affect several pathways involved in inflammation, tumor growth, and immune surveillance relevant to carcinogenesis. Also, epidemiologic evidence indicates that calcium and vitamin D may reduce risk for developing colorectal adenomas and cancer. To investigate the effects of calcium and vitamin D on biomarkers of inflammation in colorectal adenoma patients, we conducted a pilot, randomized, double-blind, placebo-controlled, 2 × 2 factorial clinical trial (n = 92) of 2 g/d calcium and/or 800 IU/d vitamin D(3) supplementation versus placebo over 6 months. Plasma concentrations of proinflammatory markers [C-reactive protein (CRP), TNF-α, interleukin (IL)-6, IL-1β, and IL-8] and an anti-inflammatory marker (IL-10) were measured using ELISAs. After 6 months of treatment, in the vitamin D(3) supplementation group, CRP decreased 32% overall (P = 0.11), 37% in men (P = 0.05), and 41% among non-nonsteroidal anti-inflammatory drug (NSAID) users (P = 0.05) relative to placebo. In the vitamin D(3) supplementation group, TNF-α decreased 13%, IL-6 32%, IL-1β 50%, and IL-8 15%; in the calcium supplementation group, IL-6 decreased 37%, IL-8 11%, and IL-1β 27%. Although these changes were not statistically significant, a combined inflammatory markers z-score decreased 77% (P = 0.003) in the vitamin D(3) treatment group overall, 83% (P = 0.01) among men, and 48% among non-NSAID users (P = 0.01). There was no evidence of synergy between vitamin D(3) and calcium or effects on IL-10. These preliminary results are consistent with a pattern of reduction in tumor-promoting inflammation biomarkers with vitamin D(3) or calcium supplementation alone and support further investigation of vitamin D(3) as a chemopreventive agent against inflammation and colorectal neoplasms.

School milk and risk of colorectal cancer: a national case-control study

To determine whether school milk consumption in childhood decreased the risk of adult colorectal cancer, the authors conducted a national population-based, case-control study of 562 cases and 571 controls. The authors identified new cases of colorectal cancer in 2007 among people aged 30-69 years from the New Zealand Cancer Registry. Controls were randomly selected from the electoral rolls and frequency matched to cases in 5-year age groups. Participation in school milk programs was associated with a reduced odds ratio for colorectal cancer (odds ratio (OR) = 0.70, 95% confidence interval (CI): 0.51, 0.96). Odds ratios decreased with increasing numbers of bottles of milk drunk compared with no school milk (for 1-799 bottles, OR = 1.04, 95% CI: 0.66, 1.67; for 800-1,199 bottles, OR = 0.81, 95% CI: 0.51, 1.29; for 1,200-1,599 bottles, OR = 0.62, 95% CI: 0.41, 0.93; for 1,600-1,799 bottles, OR = 0.57, 95% CI: 0.37, 0.90; and for 1,800 or more bottles, OR = 0.62, 95% CI: 0.41, 0.96). Participation in school milk programs in New Zealand was associated with a 2.1% reduction (95% CI: 0.7, 3.5) in the odds ratio for colorectal cancer for every 100 half-pint bottles drunk (1 half-pint bottle = 284 mL).

Epidemiological and clinical studies of nutrition

In this review, we briefly summarize some of the key developments in nutritional epidemiology and cancer over the past two decades with a focus on the strengths and limitations of study designs and dietary assessment methods. We present the evidence on dietary fat, meat, fiber, antioxidant nutrients, and calcium in relation to carcinogenesis from large cohort studies and randomized clinical trials (RCTs) and refer to the conclusions of the 2007 World Cancer Research Fund/American Institute for Cancer Research summary report. One prominent theme that emerged is the lack of concordance of results from RCTs and observational studies. There are multiple potential reasons for these discrepancies, including differences in study population, dose and timing of the exposure, adherence to an intervention, length of follow-up, and the primary endpoint. Therefore, null findings of RCTs do not necessarily indicate a lack of effect for the tested dietary factors on cancer risk, as some of these nutrients may have chemopreventive effects if given at the right time and in the right dose. It is likely that potential benefits from diet are due to a combination of food constituents rather than single components acting in isolation. Future efforts need to recognize the integrative nature of dietary exposures and attempt to study nutrients in the larger context of the foods and diets in which they are consumed.

Effects of supplemental vitamin D and calcium on oxidative DNA damage marker in normal colorectal mucosa: a randomized clinical trial

The exact antineoplastic effects of calcium and vitamin D(3) in the human colon are unclear. Animal and in vitro studies show that these two agents reduce oxidative stress; however, these findings have never been investigated in humans. To address this, we conducted a pilot, randomized, double-blind, placebo-controlled, 2 x 2 factorial clinical trial to test the effects of calcium and vitamin D(3) on a marker of oxidative DNA damage, 8-hydroxy-2'-deoxyguanosine (8-OH-dG), in the normal colorectal mucosa. Patients (N = 92) with at least one pathology-confirmed colorectal adenoma were treated with 2 g/d calcium and/or 800 IU/d vitamin D(3) versus placebo over 6 months. Overall labeling and colorectal crypt distribution of 8-OH-dG in biopsies of normal-appearing rectal mucosa were detected by standardized automated immunohistochemistry and quantified by image analysis. After 6 months of treatment, 8-OH-dG labeling along the full lengths of colorectal crypts decreased by 22% (P = 0.15) and 25% (P = 0.10) in the calcium and vitamin D(3) groups, respectively, but not in the calcium plus vitamin D(3) group. The estimated treatment effects were strongest among participants with higher baseline colon crypt vitamin D receptor expression (P = 0.05). Overall, these preliminary results indicate that calcium and vitamin D(3) may decrease oxidative DNA damage in the normal human colorectal mucosa, support the hypothesis that 8-OH-dG labeling in colorectal crypts is a treatable oxidative DNA damage biomarker of risk for colorectal neoplasms, and provide support for further investigation of calcium and vitamin D(3) as chemopreventive agents against colorectal neoplasms.

Intake of dairy products and risk of colorectal neoplasia

Prospective cohort studies suggest that higher intakes of dairy products, in particular milk, are associated with a decreased risk of colorectal cancer (CRC). In Western populations, dairy products are major contributors to dietary Ca, which may have chemopreventive effects in the colon. The pooling of data from prospective studies suggests a significant protective effect of Ca on CRC risk. Randomised controlled trials with Ca supplements have been conducted with both colorectal adenoma and CRC as endpoints. Results suggest that Ca supplementation at a level of 1000-2000 mg/d reduces adenoma recurrence in individuals with a previous adenoma but has no effect on CRC incidence. There is evidence that the risk reduction from dairy foods may not be solely due to their high Ca content. Dairy products contain other potential chemopreventive components such as vitamin D, butyric acid, conjugated linoleic acid, sphingolipids, and probiotic bacteria in fermented products such as yoghurt. The present review will focus on the epidemiological evidence (and in particular prospective cohort studies) investigating the relationship between dairy product consumption and risk of CRC. An outline of the proposed mechanisms responsible for the protective effect of both Ca and other potential chemopreventive components in dairy products will also be presented.

Effects of vitamin D and calcium supplementation on markers of apoptosis in normal colon mucosa: a randomized, double-blind, placebo-controlled clinical trial

To further clarify and/or develop calcium and vitamin D as chemopreventive agents against colorectal cancer in humans, understand the mechanisms by which these agents reduce risk for the disease, and develop "treatable" biomarkers of risk for colorectal cancer, we conducted a pilot, randomized, double-blind, placebo-controlled, 2 x 2 factorial clinical trial to test the effects of calcium and vitamin D3, alone and in combination on markers of apoptosis, in the normal colorectal mucosa. Ninety-two men and women with at least one pathology-confirmed colorectal adenoma were treated with 2.0 g/d calcium or 800 IU/d vitamin D3, alone or in combination, versus placebo over 6 months. Overall expression and colorectal crypt distributions of Bcl-2 (an apoptosis inhibitor) and Bax (an apoptosis promoter) in biopsies of normal-appearing rectal mucosa were detected by automated immunohistochemistry and quantified by image analysis. After 6 months of treatment, Bax expression along the full lengths of crypts increased 56% (P = 0.02) in the vitamin D group and 33% in both the calcium (P = 0.31) and calcium plus vitamin D (P = 0.36) groups relative to the placebo group. The vitamin D treatment effect was more pronounced in the upper 40%, or differentiation zone, of crypts (80%; P = 0.01). There were no statistically significant treatment effects on Bcl-2 expression. Overall, these preliminary results suggest that calcium and vitamin D, individually or together, may enhance apoptosis in the normal human colorectal epithelium, and the strongest treatment effects may be vitamin D related and in the upper sections of the colorectal crypts.

Effects of combination of calcium and aspirin on azoxymethane-induced aberrant crypt foci formation in the colons of mice and rats

Human intervention studies have suggested an exciting synergistic action between calcium supplementation and aspirin intake in reducing the risk of colorectal cancer. The aim of this study was to determine whether such a synergy can be demonstrated on azoxymethane (AOM)-induced colon aberrant crypt foci (ACF) formation in mice and rats. Female CF-1 mice and male F344 rats were injected subcutaneously with AOM and then received diet treatments for 8 wk. The basal control diet contained high fat (20% mixed lipids by weight) and low calcium (1.4 mg/g diet) to mimic the average Western diet. The treatment diets contained enriched calcium (5.2 mg calcium/g diet), aspirin (0.2 mg aspirin/g diet), or calcium plus aspirin (5.2 mg calcium plus 0.2 mg aspirin/g diet). Treatment with calcium, aspirin, or their combination significantly decreased the number of total ACF and aberrant crypt per mouse (by 43-59%) or rat (by 23-38%), but statistically significant differences among the 3 groups were not observed. A hint of additivity between calcium and aspirin was observed in mice but not in rats. These results indicate that the combination of calcium and aspirin did not produce a synergistic effect on the ACF formation in AOM-treated mice and rats.

Diet and cancer prevention: the roles of observation and experimentation

Observational epidemiology and experimentation by randomized controlled trials (RCTs) have been used to evaluate dietary factors in cancer prevention; however, consistency in findings has been elusive. In several circles, RCTs are viewed as more credible than observational studies. As the testing of dietary epidemiological findings in RCTs has been more common for colorectal cancer than for other cancers, we use experience with this malignancy to critically appraise the reasons for discrepancies between results of observational and experimental studies.

Calcium, calcium-sensing receptor and colon cancer

There is much evidence that dietary Ca(2+) loading reduces colon cell proliferation and carcinogenesis in humans and rodents, but during carcinogenesis it becomes ineffective or even tumor-promoting. We are beginning to see how Ca(2+) balances the continuous massive cell production in colon crypts by driving the terminal differentiation and eventually the apoptosis of the cells mainly on the mucosal surface, and how this Ca(2+) control is lost during colon carcinogenesis. The rapid proliferation of the transit-amplifying (TA) progeny of the colon stem cells is driven by the so-called "Wnt" signaling mechanism, which involves the stimulation of proliferogenic genes such as those for c-Myc and cyclin D1 and the silencing of the gene for the cell cycle-stopping p21(Cip1/WAF1) protein by nuclear beta-catenin*Tcf-4 complexes. TA cells avoid mitotic damage and premature apoptosis by expressing the protein survivin. It appears that TA cell cycling stops and terminal differentiation starts when the cells reach a higher level in the crypt where there is enough lumenal Ca(2+) to stimulate the expression and activation of CaSRs (Ca(2+)-sensing receptors), the signals from which stimulate the expression of E-cadherin. Along with this, the APC (adenomatous polyposis coli) protein appears and some of it enters the nucleus. There it makes the TA cells susceptible to the eventual apoptotic balancing by stopping survivin expression and the beta-catenin*Tcf-4 complex from driving further cell cycling by releasing beta-catenin from the nucleus, and delivering it to cytoplasmic APC*axin*GSK-3beta complexes for ultimate proteasomal destruction. Cytoplasmic beta-catenin is then prevented from returning to the nucleus by either being intercepted and destroyed by APC*axin*GSK-3beta complexes or locked by the emerging E-cadherin into membrane adherens junctions which tie the cell into the sheet of proliferatively shut-down cells with APC-dependent cytoskeletons moving to the mouth of the crypt and onto the flat mucosal surface. A common first step in sporadic colon carcinogenesis is the loss of functional APC which disorients upwardly directed migration and causes the retention of nuclear beta-catenin and proliferogenic beta-catenin*Tcf-4 complexes as well as genomic instability. Eventually the balance between cell proliferation and terminal differentiation and death is radically tipped in favour of proliferation by the appearance of apoptosis-resistant, survivin-expressing clones of Ca(2+)-insensitive cells which are locked into the proliferative, mutation-prone mode because of CaSR-disabling gene mutations which prevent the stimulation of E-cadherin expression and terminal differentiation.

Dietary carbohydrate, glycemic index, and glycemic load and the risk of colorectal cancer in the BCDDP cohort

BACKGROUND

There is considerable support for associations between insulin and IGF-I levels and colorectal cancer. Diet may relate to colorectal cancer through this mechanism, for example, diets high in glycemic index, glycemic load and/or carbohydrate are hypothesized to increase insulin load and the risk of insulin resistance, hyperinsulinemia. Case-control studies support this hypothesis, but prospective cohorts have had mixed results.

METHODS

In the Breast Cancer Detection Demonstration Project (BCDDP) follow-up cohort of 45,561 women, we used Cox proportional hazards regression to assess the distribution of 490 incident cases of colorectal cancer ascertained during 8.5 years of follow-up across quintiles of carbohydrate intake, glycemic index, and glycemic load. We also stratified by combined BMI and physical activity levels.

RESULTS

We found reductions in colorectal cancer risk for diets high in carbohydrate (RR for Q5 vs. Q1 = 0.70, 95% CI: 0.50-0.97) and glycemic index (0.75, 95% CI: 0.56-1.00), and no significant association for glycemic load (0.91, 95% CI: 0.70-1.20). Inverse associations were weakest in normal weight active persons. The inverse association for glycemic index was strongest for the portion from dairy food.

CONCLUSIONS

These results do not support an association between diets high in carbohydrate, glycemic index or glycemic load and colorectal cancer.

Calcium, dietary, and lifestyle factors in the prevention of colorectal adenomas

BACKGROUND

Many studies have suggested a role for calcium in reducing the risk of colorectal adenomas and cancer but its effectiveness may be dependent on interactions with other dietary and/or lifestyle factors. We examined the association between calcium and prevalence of adenomas and assessed whether the association was stronger in biologically plausible subgroups.

METHODS

Cross-sectional data from 222 cases and 479 adenoma-free controls who underwent colonoscopies and completed food frequency and lifestyle questionnaires were used in the analyses. Multivariable logistic regression was used to estimate the association between calcium and prevalence of adenomas. Stratified analyses and the likelihood ratio test were used to examine effect modification by various demographic, lifestyle, and behavioral factors.

RESULTS

Overall, little association was observed comparing total calcium intake of > or = 900 mg/day to < 500 mg/day (adjusted odds ratio [OR] = 0.85, 95% confidence interval [CI]: 0.53-1.37). However, stronger associations were observed in patients with lower fat intake and in those who regularly (> or = 15 times/month) took nonsteroidal antiinflammatory drugs (NSAIDs). Specifically, total calcium intake of > or = 900 mg/day was associated with a lower prevalence of adenomas among patients with lower fat intake (OR = 0.47, 95% CI: 0.25-0.91) but not among those with higher fat intake (OR = 1.20, 95% CI: 0.61-2.35; P-value for interaction = .01). For NSAIDs, the associations were OR = 0.37 (95% CI: 0.16-0.86) for regular NSAID users and OR = 1.27 (95% CI: 0.73-2.22) with infrequent or nonuse of NSAIDs, respectively (P = .06).

CONCLUSIONS

The data suggest that a lower-fat diet and regular NSAID use may enhance calcium's effectiveness as a colorectal cancer preventive agent.

Milk, dairy products and cancer risk (Italy)

BACKGROUND

Inconclusive information is available on the potential role of milk and dairy products on the risk of cancer at several sites.

METHODS

We analyzed data from a large and integrated network of hospital-based case-control studies in Italy on cancers of the oral cavity and pharynx (598 cases, 1491 controls), oesophagus (304 cases, 743 controls), colorectum (1953 cases, 4154 controls), larynx (460 cases, 1088 controls), breast (2569 cases, 2588 controls), ovary (1031 cases, 2411 controls) and prostate (1294 cases, 1451 controls).

RESULTS

Multivariate odds ratio (OR) for the highest consumption level of any type of milk was 0.94 (95% confidence interval, CI: 0.61-1.33) for cancers of the oral cavity and pharynx, 1.20 (95% CI: 0.76-1.90) for oesophageal, 0.77 (95% CI: 0.62-0.96) for colon, 0.80 (95% CI: 0.60-1.05) for rectal, 0.83 (95% CI: 0.56-1.21) for laryngeal, 0.91 (95% CI: 0.76-1.10) for breast, 0.89 (95% CI: 0.68-1.15) for ovarian and 1.08 (95% CI: 0.84-1.37) for prostate cancer. A significant trend in risk was found for colon cancer only. Inverse associations were observed between consumption of skim milk and cancers of colon (OR=0.84; 95% CI: 0.73-0.97), rectum (OR=0.76; 95% CI: 0.64-0.91), breast (OR=0.87; 95% CI: 0.77-0.98) and ovary (OR=0.77; 95% CI: 0.66-0.91). Conversely, whole milk consumption was directly associated with cancer of the rectum (OR=1.22; 95% CI: 1.03-1.44) and ovary (OR=1.25; 95% CI: 1.07-1.46). High consumption of cheese was inversely related to colon cancer risk (OR=0.80; 95% CI: 0.67-0.95).

CONCLUSIONS

There was a modest direct association between milk and dairy products and prostate cancer, and a moderate inverse one for colorectal cancer. However, our findings indicate that milk and dairy products are not strong risk indicators for any of the cancers considered.

Dairy foods, dietary calcium and obesity: a short review of the evidence

The possible association between dairy products consumption and body weight regulation has been the subject of several recent publications. The interest in this issue arose after biologically plausible mechanisms for this association were identified: most of these suggested a key role for calcium intake from dairy products, although calcium-independent mechanisms have also been proposed. Data from cross-sectional epidemiological studies support the hypothesis that a dairy food-rich diet is associated with lower fat accumulation in adults and children; however, prospective studies and randomised controlled intervention trials have yielded inconsistent results. Different reasons could explain these findings that regard the evaluation of either the "exposure" (i.e. the methodological problems in the assessment of dietary intake of nutrients over a long time) and the "outcome" (i.e. multiple factors involved in the regulation of body weight). Moreover, it could also be hypothesised that high consumption of dairy foods would be a marker of healthier lifestyles, or that nutritional differences exist within dairy products. Available data do not unequivocally support the hypothesis that a causal relationship exists between high dairy food intake--and/or high dietary calcium intake--and lower fat mass deposition. However, research in this field should aim to define the health impact of dairy foods even beyond obesity.

Calcium plus vitamin D supplementation and the risk of colorectal cancer

BACKGROUND

Higher intake of calcium and vitamin D has been associated with a reduced risk of colorectal cancer in epidemiologic studies and polyp recurrence in polyp-prevention trials. However, randomized-trial evidence that calcium with vitamin D supplementation is beneficial in the primary prevention of colorectal cancer is lacking.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial involving 36,282 postmenopausal women from 40 Women's Health Initiative centers: 18,176 women received 500 mg of elemental calcium as calcium carbonate with 200 IU of vitamin D3 [corrected] twice daily (1000 mg of elemental calcium and 400 IU of vitamin D3) and 18,106 received a matching placebo for an average of 7.0 years. The incidence of pathologically confirmed colorectal cancer was the designated secondary outcome. Baseline levels of serum 25-hydroxyvitamin D were assessed in a nested case-control study.

RESULTS

The incidence of invasive colorectal cancer did not differ significantly between women assigned to calcium plus vitamin D supplementation and those assigned to placebo (168 and 154 cases; hazard ratio, 1.08; 95 percent confidence interval, 0.86 to 1.34; P=0.51), and the tumor characteristics were similar in the two groups. The frequency of colorectal-cancer screening and abdominal symptoms was similar in the two groups. There were no significant treatment interactions with baseline characteristics.

CONCLUSIONS

Daily supplementation of calcium with vitamin D for seven years had no effect on the incidence of colorectal cancer among postmenopausal women. The long latency associated with the development of colorectal cancer, along with the seven-year duration of the trial, may have contributed to this null finding. Ongoing follow-up will assess the longer-term effect of this intervention. (ClinicalTrials.gov number, NCT00000611.).

Association of Genetic Variants in the Calcium-Sensing Receptor with Risk of Colorectal Adenoma

Objective: Evidence suggests that calcium prevents colorectal cancer, possibly mediated through the calcium-sensing receptor (CASR). We assessed the associations between CASR gene variants and risk for colorectal adenoma, a cancer precursor. We further investigated gene-diet interactions between the CASR variants and calcium intake on adenoma risk.

Methods: Individuals with advanced distal adenomas (n = 716) and controls with a negative sigmoidoscopy exam (n = 729) were randomly selected from participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Three nonsynonymous variants in the intracellular signaling region of CASR (A986S, R990G, Q1011E) were analyzed by Taqman.

Results: Compared with the most common diplotype (haplotype pair), the odds ratios for advanced adenoma were 0.80 [95% confidence interval (CI), 0.60-1.06], 0.79 (95% CI, 0.55-1.13), and 0.56 (95% CI, 0.36-0.88) for the other three common diplotypes (&gt;5% frequency). Although calcium intake was inversely associated with adenoma risk, CASR diplotypes did not modify this association. However, the power to investigate interactions was limited.

Conclusion: Variants in the CASR intracellular signaling region were significantly associated with the risk of advanced adenoma.