Hormone replacement therapy, reproductive history, and colon cancer: a multicenter, case-control study in the United States

The impact of biological clock and sex hormones on the risk of disease

Molecular clocks are responsible for defining 24-h cycles of behaviour and physiology that are called circadian rhythms. Several structures and tissues are responsible for generating these circadian rhythms and are named circadian clocks. The suprachiasmatic nucleus of the hypothalamus is believed to be the master circadian clock receiving light input via the optic nerve and aligning internal rhythms with environmental cues. Studies using both in vivo and in vitro methodologies have reported the relationship between the molecular clock and sex hormones. The circadian system is directly responsible for controlling the synthesis of sex hormones and this synthesis varies according to the time of day and phase of the estrous cycle. Sex hormones also directly interact with the circadian system to regulate circadian gene expression, adjust biological processes, and even adjust their own synthesis. Several diseases have been linked with alterations in either the sex hormone background or the molecular clock. So, in this chapter we aim to summarize the current understanding of the relationship between the circadian system and sex hormones and their combined role in the onset of several related diseases.

Estrogen receptor beta expression in colitis-associated carcinoma in comparison with sporadic colonic tumor: An immunohistochemical study

Background and Aim

The rate of ulcerative colitis (UC)-related colorectal cancer (colitis-associated carcinoma) is increasing. Estrogen receptor (ER) beta expression has been studied separately in patients with sporadic colorectal cancer and those with colitis-associated carcinoma. However, no study has compared the expression in both of these cancer types. The present study aimed to evaluate the relationship between colitis-associated carcinoma and ERs and assess whether the expression of ER beta influences cell proliferation.

Methods

This study included 45 surgically operated colitis-associated carcinomas, 43 high-grade dysplasias, 34 low-grade dysplasias, 36 sporadic colorectal cancers, 44 high-grade adenomas, and 34 low-grade adenomas. ER beta expression was evaluated with immunohistochemistry.

Results

Colitis-associated carcinoma showed significantly lower ER beta immunoexpression than sporadic colorectal lesions and high- and low-grade dysplasia. In seven colitis-associated carcinoma harboring both intensity score 3 (strong immunoexpression) and score 1 (weak immunoexpression) areas, the correlation among ER beta intensity, Ki-67, and p21 labeling index was assessed; an area with an ER beta intensity score of 3 showed a higher Ki-67 labeling index than that with score 1. In four out of the seven lesions, p21 labeling index was higher in the area of ER beta score 1 than in that of ER beta score 3.

Conclusions

The data suggest that ER beta expression is an accelerating factor in colorectal tumors. This association may be lower in colitis-associated carcinoma than in sporadic colorectal cancer.

Oral contraceptives and colorectal cancer risk - A meta-analysis and systematic review

There is limited understanding of the potential relationship between the risk of colorectal cancer and oral contraceptive use among women of different ages. Further investigation on the issue helps develop an informed choice of contraception. Data for this meta-analysis were derived from case-control and cohort studies of colorectal cancer and oral contraceptive use conducted between June 2000 and May 2022. The studies had a very high heterogeneity, as shown by an I² of 99%, and a confidence interval of 95% was considered significant. Other results from the meta-analysis were as follows; Heterogeneity: Chi² = 585.13, df = 6 (P < 0.00001). A test of the overall effect of ever use versus never use of oral contraceptives was Z = 21.85 (P < 0.00001). All the studies had a pooled risk ratio (RR) of 0.53. The use of oral contraceptives is associated with reduced risk of developing colorectal cancer. There is a need for further research into the biological mechanisms underlying these relationships, which may lead to insights into potential preventive interventions for colorectal carcinogenesis in women. The keywords used to locate studies included in this meta-analysis include Keywords targeting oral contraceptives included oral contraceptive pills, and birth control pills. Search keywords targeting colorectal carcinogenesis included neoplasms, tumors, or colon and rectal cancer.

•

Oral contraceptive use in woman does affect the risk of developing colorectal cancer.

•

Colorectal cancer has many identifiable and nonidentifiable risk factors.

•

OCP usage in women of various age groups shown a lower risk of colorectal cancer development than those who never used OCPs.

•

Regarding the population at risk for colorectal cancer due to a variety of reasons, many studies have deemed OCP usage safe.

Overweight and Obesity Determine the Risk for Gastrointestinal Cancer in a Sex-Dependent Manner: A Retrospective Cohort Study of 287,357 Outpatients in Germany

Cancer represents the second leading cause of death worldwide, implementing a major health care and socioeconomic burden. Overweight and obesity, both of which are dramatically on the rise in both highly and less developed regions worldwide, have been established as modifiable risk factors for the development of various tumor entities including gastrointestinal (GI) cancers such as colorectal or gastric cancer. However, systematic data on an association between excessive body fat and GI cancer development from Germany are missing. Methods: A total of 287,357 adult outpatients with an available BMI value between 2010 and 2019 were identified from the Disease Analyzer database (IQVIA). The main outcome was the association between pre-obesity (BMI 25–30 kg/m2) and obesity (BMI ≥ 30 kg/m2) compared to normal weight (BMI 18.5–25 kg/m2) and the incident of a GI cancer diagnoses (including colon, rectum, stomach, pancreas, and liver cancer). Results: Within the observation period, the proportion of colon cancer patients increased stepwise from 0.5% and 0.64% in normal weight to 0.71% and 0.91% in obese female and male patients, respectively, which was confirmed in multivariable regression models (ORfemale obesity: 1.23; 95% CI: 1.03–1.48; ORmale obesity: 1.43, 95% CI: 1.17–1.74). In contrast, multivariable regression models revealed that obesity was significantly associated with rectal cancer (OR: 1.36, 95% CI: 1.01–1.84) as well as liver cancer (OR: 1.79, 95% CI: 1.17–2.73) in men only. Conclusions: Our data suggest that obesity represents a decisive risk factor for the development of colon, rectal, and liver cancer, partly in a sex-dependent manner. Since overweight and obesity are modifiable risk factors, the current results may help to establish appropriate prevention and lifestyle programs to reduce both the incidence as well as the high morbidity and mortality of GI tumors in the future.

Predictors of CRC Stage at Diagnosis among Male and Female Adults Participating in a Prospective Cohort Study: Findings from Alberta's Tomorrow Project

Colorectal cancer (CRC) is a leading cause of morbidity and mortality in Canada. CRC screening and other factors associated with early-stage disease can improve CRC treatment efficacy and survival. This study examined factors associated with CRC stage at diagnosis among male and female adults using data from a large prospective cohort study in Alberta, Canada. Baseline data were obtained from healthy adults aged 35–69 years participating in Alberta’s Tomorrow Project. Factors associated with CRC stage at diagnosis were evaluated using Partial Proportional Odds models. Analyses were stratified to examine sex-specific associations. A total of 267 participants (128 males and 139 females) developed CRC over the study period. Among participants, 43.0% of males and 43.2% of females were diagnosed with late-stage CRC. Social support, having children, and caffeine intake were predictors of CRC stage at diagnosis among males, while family history of CRC, pregnancy, hysterectomy, menopausal hormone therapy, lifetime number of Pap tests, and household physical activity were predictive of CRC stage at diagnosis among females. These findings highlight the importance of sex differences in susceptibility to advanced CRC diagnosis and can help inform targets for cancer prevention programs to effectively reduce advanced CRC and thus improve survival.

A sex-specific propensity-adjusted analysis of colonic adenoma detection rates in a screening cohort

The prevalence of colorectal adenoma and advanced adenoma (AA) differs between sexes. Also, the optimal age for the first screening colonoscopy is under debate. We, therefore, performed a sex-specific and age-adjusted comparison of adenoma, AA and advanced neoplasia (AN) rates in a real-world screening cohort. In total, 2824 asymptomatic participants between 45- and 60-years undergoing screening colonoscopy at a single-centre in Austria were evaluated. 46% were females and mean age was 53 ± 4 years. A propensity score for being female was calculated, and adenoma, AA and AN detection rates evaluated using uni- and multivariable logistic regression. Sensitivity analyses for three age groups (group 1: 45 to 49 years, n = 521, 41% females, mean age 47 ± 1 years; group 2: 50 to 54 years, n = 1164, 47% females, mean age 52 ± 1 years; group 3: 55 to 60 years, n = 1139, 46% females, mean age 57 ± 2 years) were performed. The prevalence of any adenoma was lower in females (17% vs. 30%; OR 0.46, 95% CI 0.38–0.55; p < 0.001) and remained so after propensity score adjustment for baseline characteristics and lifestyle factors (aOR 0.52, 95% CI 0.41–0.66; p < 0.001). The same trend was seen for AA with a significantly lower prevalence in females (3% vs. 7%; OR 0.38, 95% CI 0.26–0.55; p < 0.001) that persisted after propensity score adjustment (aOR 0.54, 95% CI 0.34–0.86; p = 0.01). Also, all age-group sensitivity analyses showed lower adenoma, AA and AN rates in females. Similar numbers needed to screen to detect an adenoma, an AA or AN were found in female age group 3 and male age group 1. Colorectal adenoma, AA and AN were consistently lower in females even after propensity score adjustment and in all age-adjusted sensitivity analyses. Our study may add to the discussion of the optimal age for initial screening colonoscopy which may differ between the sexes.

Impact of menopausal hormone therapy on colorectal cancer risk-A systematic review

Colorectal cancer (CRC) is the second most frequently diagnosed cancer in females worldwide. Menopausal hormone therapy (MHT) has been proposed as a potential protective factor for the development of CRC. Yet, the available evidence is controversial. Thus, we aimed at summarizing the current evidence on the effect of MHT on CRC through a systematic review. A systematic literature search identified 1001 potentially relevant articles, out of which 57 original studies and nine meta-analyses were deemed eligible for the final synthesis. The evidence synthesis showed the following: (1) MHT showed a heterogeneity in findings for CRC risk with a slight tendency to a neutral or protective effect; (2) MHT effect was either neutral or protective on colorectal adenoma; (3) MHT had no impact on tumour grade, subsite and histologic types; (4) MHT was not associated with CRC mortality; and (5) MHT showed heterogeneous effects on CRC stage and invasiveness, respectively. In summary, despite some evidence pointing towards a protective effect of MHT on CRC, MHT is currently not recommended for primary CRC prevention by international guidelines due to several important, potentially harmful effects.

Sexual Dimorphism in Colon Cancer

A higher incidence of colorectal cancer (CRC) is found in males compared to females. Young women (18-44 years) with CRC have a better survival outcome compared to men of the same age or compared to older women (over 50 years), indicating a global incidence of sexual dimorphism in CRC rates and survival. This suggests a protective role for the sex steroid hormone estrogen in CRC development. Key proliferative pathways in CRC tumorigenesis exhibit sexual dimorphism, which confer better survival in females through estrogen regulated genes and cell signaling. Estrogen regulates the activity of a class of Kv channels (KCNQ1:KCNE3), which control fundamental ion transport functions of the colon and epithelial mesenchymal transition through bi-directional interactions with the Wnt/β-catenin signalling pathway. Estrogen also modulates CRC proliferative responses in hypoxia via the novel membrane estrogen receptor GPER and HIF1A and VEGF signaling. Here we critically review recent clinical and molecular insights into sexual dimorphism of CRC biology modulated by the tumor microenvironment, estrogen, Wnt/β-catenin signalling, ion channels, and X-linked genes.

Hormonal and reproductive factors and reduction in the risk of colorectal cancer

Females differ from males in incidence and clinical characteristics of colorectal cancer. Understanding the differences can lead to development of preventive approaches. To identify reproductive factors currently associated with the risk of colorectal cancer. Consecutively diagnosed female colorectal cancer cases and randomly chosen colorectal cancer-free controls matched on age/ethnicity/primary care clinic within the molecular epidemiology of colorectal cancer study, a population-based case-control study in Northern Israel, were included. A total of 2867 female cases and 2333 controls participated in this analysis. Participants were interviewed on reproductive history: ages at menarche, menopause, first birth, terminations of pregnancies, miscarriages, births, use of oral contraceptives. Among 5200 women, spontaneous miscarriages (odds ratio = 0.71, 0.61-0.83 for ever/never in Jews; odds ratio = 0.76, 0.53-1.08 in Arabs) and number of miscarriages, but not termination of pregnancies, as well as use, and duration of use, of oral contraceptives (Jews: odds ratio = 0.49, 0.39-0.62 for ever/never; Arabs: odds ratio = 0.14, 0.04-0.47) were strongly inversely associated with colorectal cancer risk. Up to 5 pregnancies were associated with increased risk while ages at menarche, at menopause and at first birth were not associated with colorectal cancer risk. Miscarriages but not terminations of pregnancy or full-term pregnancies, and use of oral contraceptives, were strongly associated with reduced odds of developing colorectal cancer suggesting unique hormonal influences on colorectal cancer.

Menopausal hormone therapy and colorectal cancer: a linkage between nationwide registries in Norway

OBJECTIVES

With the present study, we aimed to investigate the association between menopausal hormone therapy (HT) and risk of colorectal cancer (CRC).

SETTING

Cohort study based on the linkage of Norwegian population-based registries.

PARTICIPANTS

We selected 466822 Norwegian women, aged 55-79, alive and residing in Norway as of 1 January 2004, and we followed them from 2004 to 2008. Each woman contributed person-years at risk as non-user, current user and/or past HT user.

OUTCOME MEASURES

The outcome of interest was adenocarcinoma of the colorectal tract, overall, by anatomic site and stage at diagnosis. Incidence rate ratios (RRs) with 95% CIs were estimated by Poisson regression and were used to evaluate the association between HT and CRC incidence.

RESULTS

During the median follow-up of 4.8 years, 138 655 (30%) women received HT and 3799 (0.8%) incident CRCs occurred. Current, but not past, use of HT was associated with a lower risk of CRC (RR 0.88; 95% CI 0.80 to 0.98). RRs for localised, regionally advanced and metastatic CRC were 1.13 (95% CI 0.91 to 1.41), 0.81 (95% CI 0.70 to 0.94) and 0.79 (95% CI 0.62 to 1.00), respectively. RRs for current use of oestrogen therapy (ET) were 0.91 (95% CI 0.80 to 1.04) while RR for current use of combined oestrogen-progestin therapy (EPT) was 0.85 (95% CI 0.70 to 1.03), as compared with no use of HT. The same figures for ET and EPT in oral formulations were 0.83 (95% CI 0.68 to 1.03) and 0.86 (95% CI 0.71 to 1.05), respectively.

CONCLUSIONS

In our nationwide cohort study, HT use lowered the risk of CRC, specifically the most advanced CRC.

Is there a sex effect in colon cancer? Disease characteristics, management, and outcomes in routine clinical practice

INTRODUCTION

The incidence of colon cancer varies by sex. Whether women and men show differences in extent of disease, treatment, and outcomes is not well described. We used a large population-based cohort to evaluate sex differences in colon cancer.

METHODS

Using the Ontario Cancer Registry, all cases of colon cancer treated with surgery in Ontario during 2002-2008 were identified. Electronic records of treatment identified use of surgery and adjuvant chemotherapy. Pathology reports for a random 25% sample of all cases were obtained, and disease characteristics, treatment, and outcomes in women and men were compared. A Cox proportional hazards model was used to identify factors associated with overall (os) and cancer-specific survival (css).

RESULTS

The study population included 7249 patients who underwent resection of colon cancer; 49% (n = 3556) were women. Stage of disease and histologic grade did not vary by sex. Compared with men, women were more likely to have right-sided disease (55% vs. 44%, p ≤ 0.001). Surgical procedure and lymph node yield did not differ by sex. Adjuvant chemotherapy was delivered to 18% of patients with stage ii and 64% of patients with stage iii disease; when adjusted for patient- and disease-related factors, use of adjuvant chemotherapy was similar for women and men [relative risk: 0.99; 95% confidence interval (ci): 0.94 to 1.03]. Adjusted analyses demonstrated that os [hazard ratio (hr): 0.80; 95% ci: 0.75 to 0.86] and css (hr: 0.82; 95% ci: 0.76 to 0.90) were superior for women compared with men.

CONCLUSIONS

Long-term survival after colon cancer is significantly better for women than for men, which is not explained by any substantial differences in extent of disease or treatment delivered.

A prospective study of oral contraceptive use and colorectal adenomas

PURPOSE

The influence of reproductive factors on colorectal cancer, including oral contraceptive (OC) use, has been examined, but less research is available on OC use and adenomas.

METHODS

Participants of the Nurses' Health Study who had a lower bowel endoscopy between 1986 (when endoscopies were first assessed) and 2008 were included in this study. Multivariable logistic regression models for clustered data were used to estimate odds ratios and 95 % confidence intervals [OR (95 % CIs)].

RESULTS

Among 73,058 participants, 51 % (n = 37,382) reported ever using OCs. Ever OC use was associated with a slight increase in non-advanced adenomas [OR 1.11, 95 % CI (1.02, 1.21)] but not with any other endpoints. Duration of OC use was not associated with adenomas, but longer times since last OC use were associated with increased odds of adenomas [e.g., compared to never use, 15+ years since last use: OR 1.17 (1.07, 1.27)]. Shorter times since last OC use were inversely associated [e.g., ≤4 years since last use: OR 0.74 (0.65, 0.84)].

CONCLUSIONS

We observed a modest borderline increase in risk of colorectal adenomas with any prior OC use. Additionally, more recent OC use may decrease risk, while exposure in the distant past may modestly increase risk of adenomas.

Oral contraceptive use and colorectal cancer in the Nurses' Health Study I and II

BACKGROUND

It remains unclear if oral contraceptive (OC) use is associated with the incidence of colorectal cancer. Few studies have examined this association by duration of OC use, time since last OC use, and different cancer subsites.

METHODS

Among 88,691 participants of the Nurses' Health Study I (NHSI) and 93,080 participants of the Nurses' Health Study II (NHSII), we assessed OC use every 2 years between 1976 and 2010 and categorized it as ever use, duration of use, and time since last use. We included incident colorectal cancer cases through 2010 (NHSI: age at diagnosis = 36-88, N = 1,764; NHSII: age at diagnosis = 33-64, N = 206). Multivariable hazard ratios and 95% confidence intervals were estimated using Cox proportional hazards regression models.

RESULTS

Ever OC use was not associated with colorectal cancer in NHSI [1.01 (0.91, 1.12)] nor NHSII [1.03 (0.69, 1.53)]. In NHSII, when compared with never-users, longer durations (5+ years) of OC use were inversely associated with the risk of colon cancers (Ptrend = 0.02) but the number of endpoints was limited. No other colorectal cancer subsites were associated with OC durations or times since last OC use in either cohort.

CONCLUSIONS

In two large prospective cohorts, we found little evidence that OC use may be protective for colorectal cancer, except potentially with longer durations of use among younger women.

IMPACT

Our results do not support the previous initial studies that reported an inverse association of recent OC use with colorectal cancer but instead support newer, larger studies demonstrating no such association.

Improved survival among colon cancer patients with increased differentially expressed pathways

BACKGROUND

Studies of colorectal cancer (CRC) have shown that hundreds to thousands of genes are differentially expressed in tumors when compared to normal tissue samples. In this study, we evaluate how genes that are differentially expressed in colon versus normal tissue influence survival.

METHODS

We performed RNA-seq on tumor/normal paired samples from 175 colon cancer patients. We implemented a cross validation strategy to determine genes that were significantly differentially expressed between tumor and normal samples. Differentially expressed genes were evaluated with Ingenuity Pathway Analysis to identify key pathways that were de-regulated. A summary differential pathway expression score (DPES) was developed to summarize hazard of dying while adjusting for age, American Joint Committee on Cancer (AJCC) stage, sex, and tumor molecular phenotype, i.e., MSI, TP53, KRAS, and CIMP.

RESULTS

A total of 1,138 genes were up-regulated and 695 were down-regulated. These de-regulated genes were enriched for 19 Ingenuity Canonical Pathways, with the most significant pathways involving cell signaling and growth. Of the enriched pathways, 16 were significantly associated with CRC-specific mortality, including 1 metabolic pathway and 15 signaling pathways. In all instances, having a higher DPES (i.e., more de-regulated genes) was associated with better survival. Further assessment showed that individuals diagnosed at AJCC Stage 1 had more de-regulated genes than individuals diagnosed at AJCC Stage 4.

CONCLUSIONS

Our data suggest that having more de-regulated pathways is associated with a good prognosis and may be a reaction to key events that are disabling to tumor progression. Please see related article: http://dx.doi.org/10.1186/s12916-015-0307-6 .

Nonlinear reduction in risk for colorectal cancer by oral contraceptive use: a meta-analysis of epidemiological studies

PURPOSE

Although the relationship between oral contraceptive (OC) use and colorectal cancer (CRC) risk has been studied extensively, the results of epidemiological studies are controversial. Therefore, we carried out a meta-analysis of epidemiological studies to summarize the available evidence and to quantify the potential dose-response relation.

METHODS

We searched PubMed database for studies of OC use and CRC risk that were published until the end of March 2014. Random- and fixed-effects models were applied to estimate summary relative risks (RRs) and 95 % confidence intervals (CIs).

RESULTS

Twelve cohorts and seventeen case-control studies with a total of 15,790 CRC cases were included in the final analysis. The summary RR for the ever versus never category of OC use was 0.82 (95 % CI 0.76-0.88). Similar result was observed when we compared the longest duration of OC use with the shortest duration (RR = 0.86, 95 % CI 0.76-0.96). Furthermore, the results of stratified analysis were comparable to those of overall meta-analysis. In dose-response analysis, significant inverse associations emerged in nonlinear models for the duration of OC use and CRC (P nonlinearity = 0.001). The greatest risk reduction was observed when the duration of OC use was approximately 42 months. There was moderate heterogeneity in the analysis, and no evidence of small-study bias was observed.

CONCLUSIONS

Based on the findings of this meta-analysis, ever use of OC is associated with lower risk of CRC. Additionally, there is a statistically significant nonlinear inverse association between the duration of OC use and CRC risk.

Reproductive history and risk of colorectal adenocarcinoma

BACKGROUND

Sex hormones may be associated with colorectal adenocarcinoma, although the association of pregnancy history and risk of colorectal cancer is not consistent.

METHODS

We conducted a population-based nested case-control study of persons born between 1932 and 2008 who are in the Swedish Multi-Generation Register. In total, 12,915 women and 15,519 men with colorectal adenocarcinoma were identified during follow-up in the Swedish Cancer Register; 10 age- and sex-matched controls were selected for each case. Number of children and age at first and last birth were analyzed in relation to the risk of colorectal adenocarcinoma, using conditional logistic regression, to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Compared with women without children, women with 1 or 2 children had an OR of 1.02 (95% CI = 0.93-1.13) of developing adenocarcinoma in the proximal colon; those with 3 or 4 children, 1.18 (1.06-1.32); and those with ≥5 children, 1.30 (1.05-1.61) (test for trend P < 0.01). The corresponding associations in men were 0.92 (0.84-1.00), 1.02 (0.92-1.13), and 0.97 (0.78-1.20), respectively (test for trend P = 0.13).

CONCLUSIONS

Higher parity in women was associated with the risk of adenocarcinoma of the proximal colon, although not the distal colon or rectum. A similar risk with family size was not seen for fathers. Still, the influence of lifestyle factors cannot be ruled out.

COX-1 (PTGS1) and COX-2 (PTGS2) polymorphisms, NSAID interactions, and risk of colon and rectal cancers in two independent populations

PURPOSE

Nonsteroidal anti-inflammatory drugs (NSAIDs) target the prostaglandin H synthase enzymes, cyclooxygenase (COX)-1 and COX-2, and reduce colorectal cancer risk. Genetic variation in the genes encoding these enzymes may be associated with changes in colon and rectal cancer risk and in NSAID efficacy.

METHODS

We genotyped candidate polymorphisms and tag SNPs in PTGS1 (COX-1) and PTGS2 (COX-2) in a population-based case–control study (Diet, Activity and Lifestyle Study, DALS) of colon cancer (n = 1,470 cases/1,837 controls) and rectal cancer (n = 583/775), and independently among cases and controls from the Colon Cancer Family Registry (CCFR; colon n = 959/1,535, rectal n = 505/839).

RESULTS

In PTGS2, a functional polymorphism (-765G[C; rs20417) was associated with a twofold increased rectal cancer risk (p = 0.05) in the DALS. This association replicated with a significant nearly fivefold increased risk of rectal cancer in the CCFR study (ORCC vs. GG = 4.88; 95 % CI 1.54–15.45; ORGC vs. GG = 1.36; 95 %CI 0.95–1.94). Genotype–NSAID interactions were observed in the DALS for PTGS1 and rectal cancer risk and for PTGS2 and colon cancer risk, but were no longer significant after correcting for multiple comparisons and did not replicate in the CCFR. No significant associations between PTGS1 polymorphisms and colon or rectal cancer risk were observed.

The p53-estrogen receptor loop in cancer

Tumor suppressor p53 maintains genome stability by regulating diverse cellular functions including cell cycle arrest, apoptosis, senescence and metabolic homeostasis. Mutations in the p53 gene occur in almost all human cancers with a frequency of up to 80%. However, it is only 20% in breast cancers, 18% in endometrial cancers and 1.5% in cervical cancers. Estrogen receptor alpha (ERα) plays a pivotal role in hormone-dependent cancer development and the status of ERα is used for designing treatment strategy and for prognosis. A closer look at the cross-talk between p53 and ERα has revealed that their activities are mutually regulated. This review will summarize the current body of knowledge on p53, ERα and ERβ in cancer. Clinical correlations between estrogen receptors and p53 status have also been reported. Thus, this review will discuss the relationship between p53 and ERs at both the molecular and clinical levels.

Inverse association of colorectal cancer prevalence to serum levels of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in a large Appalachian population

BACKGROUND

Perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) are persistent environmental contaminants that affect metabolic regulation, inflammation, and other factors implicated in the development and progression of colorectal cancer (CRC). However, the link between these compounds and CRC remains unknown. In this cross-sectional study, we investigated the association of CRC diagnosis to PFOA and PFOS blood levels in a large Appalachian population.

METHODS

Participants were 47,359 adults ≥ 21 years of age and residing in six PFOA-contaminated water districts in the mid-Ohio Valley (N = 47,151 cancer-free adults, 208 cases of primary CRC). All participants completed a comprehensive health survey between 2005 and 2006; serum levels of PFOA, PFOS, and a range of other blood markers were also measured. Medical history was assessed via self report and cancer diagnosis confirmed via chart review.

RESULTS

CRC showed a strong inverse, dose-response association with PFOS serum levels (odds ratio (OR) adjusted for potential confounders = 0.2, 95% confidence interval (CI) 0.2,0.3) for highest vs. lowest quartile of PFOS, P-trend < 0.00001) and a significant, but more modest inverse association with PFOA (adjusted OR = 0.6 (CI 0.4, 0.9) for highest vs. lowest quartile, P-trend = 0.001). These inverse associations were stronger in those diagnosed within the previous 6 years and resident in the same water district for a minimum of 10-15 years preceding assessment. The relationship between PFOA and CRC was also more pronounced in men and leaner adults, and showed a stronger linear trend at lower exposure levels.

CONCLUSIONS

In this large cross-sectional study, we found a strong, inverse association between PFOS and likelihood of CRC diagnosis and a significant, although more modest inverse association between PFOA and CRC. If confirmed in prospective investigations, these findings may aid in identifying new strategies for CRC prevention and treatment and inform future studies regarding mechanisms underlying CRC pathogenesis.

Age at menarche and risk of colorectal cancer: a meta-analysis

Background

Various observational studies have focused on the relationship between menarcheal age and the risk of colorectal cancer (CRC). However, the association is still controversial because of inconsistent results. Therefore, we performed a meta-analysis to assess this issue from epidemiological studies.

Methods

After a literature search in MEDLINE, EMBASE, and Web of Science for studies of menarcheal age and CRC risk published through the end of January 2013, we pooled the relative risks (RRs) from included studies using a fixed- or random-effects model and performed heterogeneity and publication bias analyses. All statistical tests were two-sided.

Results

Eleven case-control and 11 cohort studies were eligible for inclusion in our analysis. The random-effects pooled RR for oldest versus youngest menarcheal age was 0.95 [95% confidence intervals (CIs) = 0.85–1.06], with significant heterogeneity (Q = 61.03, P<0.001, I² = 65.6%). When separately analyzed, case-control (RR = 0.95, 95% CI = 0.75–1.21) and cohort studies (RR = 0.97, 95% CI = 0.90–1.04) yielded similar results. Moreover, similar results were also observed among the subgroup analyses by study quality, population, exposure assessment, anatomic cancer site, subsite of colon cancer, and several potential important confounders and risk factors. There was no evidence of publication bias and significant heterogeneity between subgroups detected by meta-regression analyses.

Conclusions

Findings from this meta-analysis demonstrated that menarcheal age was not associated with the risk of CRC in humans. Further studies are warranted to stratify results by the subsite of colon cancer and menopause status in the future.

Menopausal hormone therapy and risk of gastrointestinal cancer: nested case-control study within a prospective cohort, and meta-analysis

Use of menopausal hormone therapy (HT) has been associated with reduced risk of colorectal cancer; evidence for its effect on other gastrointestinal cancers is limited. We conducted a nested case-control study within a UK cohort, and meta-analyses combining our results with those from published studies. Our study included women aged 50+ in the UK General Practice Research Database (GPRD): 1,054 with oesophageal, 750 with gastric and 4,708 with colorectal cancer, and 5 age- and practice-matched controls per case. Relative risks (RRs) and 95% confidence intervals (CIs) for cancer in relation to prospectively-recorded HT prescriptions were estimated by conditional logistic regression. Women prescribed HT had a reduced risk of oesophageal cancer (adjusted RR for 1+ vs. no HT prescriptions, 0.68, 95% CI 0.53-0.88; p = 0.004), gastric cancer (0.75, 0.54-1.05; p = 0.1) and colorectal cancer (0.81, 0.73-0.90; p < 0.001). There were no significant differences in cancer risk by HT type, estimated duration of HT use or between past and current users. In meta-analyses, risks for ever vs. never use of HT were significantly reduced for all three cancers (summary RR for oesophageal cancer, 0.68, 0.55-0.84, p < 0.001; for gastric cancer, 0.78, 0.65-0.94, p = 0.008; for colorectal cancer, 0.84, 0.81-0.88, p < 0.001). In high-income countries, estimated incidence over 5 years of these three cancers combined in women aged 50-64 was 2.9/1,000 in HT users and 3.6/1,000 in never users. The absolute reduction in risk of these cancers in HT users is small compared to the HT-associated increased risk of breast cancer.

The Effects of Twins, Parity and Age at First Birth on Cancer Risk in Swedish Women

The effect of reproductive history on the risk of cervical, colorectal and thyroid cancers and melanoma has been explored but the results to date are inconsistent. We aimed to examine in a record- linkage cohort study the risk of developing these cancers, as well as breast, ovarian and endometrial cancers, among mothers who had given birth to twins compared with those who had only singleton pregnancies. Women who delivered a baby in Sweden between 1961 and 1996 and who were 15 years or younger in 1961 were selected from the Swedish civil birth register and linked with the Swedish cancer registry. We used Poisson regression to assess associations between reproductive factors and cancer. Twinning was associated with reduced risks of breast, colorectal, ovarian and uterine cancers, although no relative risks were statistically significant. The delivery of twins did not increase the risk of any cancers studied. Increasing numbers of maternities were associated with significantly reduced risks of all tumors except thyroid cancer. We found positive associations between a later age at first birth and breast cancer and melanoma, while there were inverse associations with cervix, ovarian, uterine and colorectal cancers. These findings lend weight to the hypothesis that hormonal factors influence the etiology of colorectal cancer in women, but argue against any strong effect of hormones on the development of melanoma or tumors of the thyroid.

Risk of colorectal cancer in self-reported inflammatory bowel disease and modification of risk by statin and NSAID use

BACKGROUND

Statins and nonsteroidal anti-inflammatory drugs (NSAIDs) are associated with reduced risk of colorectal cancer (CRC) in some studies. The objective of this study was to quantify the relative risk of inflammatory bowel disease (IBD) as a risk factor for CRC and to estimate whether this risk may be modified by long-term use of NSAIDs or statins.

METHODS

The Molecular Epidemiology of Colorectal Cancer study is a population-based, case-control study of incident colorectal cancer in northern Israel and controls matched by age, sex, clinic, and ethnicity. Personal histories of IBD and medication use were measured by structured, in-person interview. The relative risk of IBD and effect modification by statins and NSAIDs were quantified by conditional and unconditional logistic regression.

RESULTS

Among 1921 matched pairs of CRC cases and controls, a self-reported history of IBD was associated with a 1.9-fold increased risk of CRC (95% confidence interval [CI], 1.12-3.26). Long-term statin use was associated with a reduced risk of both IBD-associated CRC (odds ratio [OR] = 0.07; 95% CI, 0.01-0.78) and non-IBD CRC (OR = 0.49; 95% CI, 0.39-0.62). Stratified analysis suggested that statins may be more protective among those with IBD (ratio of OR = 0.14; 95% CI, 0.01-1.31; P = .51), although not statistically significant. NSAID use in patients with a history of IBD was suggestive of reduced risk of CRC but did not reach statistical significance (OR = 0.47; 95% CI, 0.12-1.86).

CONCLUSIONS

The risk of CRC was elevated 1.9-fold in patients with IBD. Long-term statin use was associated with reduced risk of CRC in patients with IBD.

Oral contraceptives, reproductive history and risk of colorectal cancer in the European Prospective Investigation into Cancer and Nutrition

BACKGROUND

Oral contraceptive use and reproductive factors may initiate long-term changes to the hormonal milieu and thereby, possibly influence colorectal cancer risk.

METHODS

We examined the association of hormonal and reproductive factors with risk of colorectal cancer among 337,802 women in the European Prospective Investigation into Cancer and Nutrition, of whom 1878 developed colorectal cancer.

RESULTS

After stratification for center and age, and adjustment for body mass index, smoking, diabetes mellitus, physical activity and alcohol consumption, ever use of oral contraceptives was marginally inversely associated with colorectal cancer risk (hazard ratio (HR), 0.92; 95% confidence interval (CI), 0.83-1.02), although this association was stronger among post-menopausal women (HR, 0.84; 95% CI: 0.74-0.95). Duration of oral contraceptive use and reproductive factors, including age at menarche, age at menopause, type of menopause, ever having an abortion, parity, age at first full-term pregnancy and breastfeeding, were not associated with colorectal cancer risk.

CONCLUSION

Our findings provide limited support for a potential inverse association between oral contraceptives and colorectal cancer risk.

The association between a functional CYP1A1 polymorphism and colorectal neoplasia risk in post menopausal women

BACKGROUND

The impact of estrogen on risk of colorectal neoplasia is uncertain. Carriers of the AA and CA genotype allele of the C4887A polymorphism of the CYP1A1 gene have enhanced estrogen metabolism relative to carriers of the CC genotype.

AIMS

This study examined whether this genetic marker of enhanced estrogen catabolism segregated with colorectal neoplasia (CRN) in postmenopausal women.

METHODS

We enrolled hormone negative postmenopausal women having screening or surveillance colonoscopy. Demographic and medical data were gathered. Blood was collected and analyzed for CYP1A1 polymorphisms of the C4887A allele by PCR-RFLP. Colonoscopy and pathology data were gathered from hospital databases.

RESULTS

One hundred sixty-eight women were enrolled in the study. Twenty-one subjects (12.5%) carried at least one A allele, and 147 subjects (87.5%) carried the CC alleles for the C4887A polymorphism of the CYP1A1 gene. Seventy subjects (41.7%) had CRN and 98 subjects (58.3%) did not have CRN. Of the subjects who carried the A allele, 57% had CRN as compared to 39% of those who carried the CC allele; the association was not statistically significant (P = 0.16). In a multivariate logistic regression analysis, age, BMI, current tobacco use, and first degree relative with CRN were independent risk factors for CRN but the C4887A polymorphisms remained not statistically significant (P = 0.35).

CONCLUSIONS

Carriers of the A allele of the C4887A polymorphism have enhanced estrogen catabolism and lower free estradiol. Our results suggest, however, that inherent estrogen metabolism as determined by C4887A polymorphisms is not associated with CRN risk.

Genetic variation in a metabolic signaling pathway and colon and rectal cancer risk: mTOR, PTEN, STK11, RPKAA1, PRKAG2, TSC1, TSC2, PI3K and Akt1

Serine/threonine protein kinase 11 (STK11) and phosphatase tensin homolog deleted on chromosome 10 (PTEN) link insulin sensitivity and metabolic signaling to inflammation and other hormonal factors and colorectal cancer. We evaluate genetic variation in nine genes in a candidate pathway as follows: STK11 (3 tagSNPs), PTEN (9 tagSNPs), FRAP1 (mTOR) (4 tagSNPs), TSC1 (14 tagSNPs), TSC2 (8 tagSNPs), Akt1 (2 tagSNPs), PIK3CA (7 tagSNPs), PRKAA1 (13 tagSNPs) and PRKAG2 (68 tagSNPs) in two population-based case-control studies of colon (n = 1574 cases, 1940 controls) and rectal (n = 91 cases, 999 controls) cancer. FRAP1, PRKAA1, PRKAG2 and TSC2 genes were significantly associated with colon cancer; risk estimates ranged from 1.21 [95% confidence interval (CI) 1.05-1.38] for FRAP1rs1057079 for the AG/GG genotype to 1.51 (95% CI 1.09-2.09) for PRKAG2rs9648723 CC genotype. PIK3CA, PRKAG2, PTEN, STK11 and TSC1 were significantly associated with rectal cancer overall. The strongest association was observed for PIK3CA rs7651265 GG genotype (odds ratio 2.32 95% CI 1.02-5.30). FRAP1 was associated with microsatellite instability (MSI)+ colon tumors; PRKAA1, CpG island methylator phenotype (CIMP)+ and MSI+ colon tumors; PRKAG2 and KRAS2 colon tumors; TSC1 and CIMP+ and MSI+ colon tumors; TSC2 with MSI+ colon tumors; PIK3CA with KRAS2-mutated rectal tumors; PRKAG2 (rs6964824) with KRAS2- and TP53-mutated rectal tumors and with PRKAG2 (rs412396 and rs4725431) with CIMP+ rectal tumors. These data suggest that genetic variation in a predefined candidate pathway for colorectal cancer contributes to both colon and rectal cancer risk. Associations appear to be strongest for CIMP+ and MSI+ tumors.

Primary prevention of colorectal cancer

Colorectal cancer has been strongly associated with a Western lifestyle. In the past several decades, much has been learned about the dietary, lifestyle, and medication risk factors for this malignancy. Although there is controversy about the role of specific nutritional factors, consideration of dietary pattern as a whole appears useful for formulating recommendations. For example, several studies have shown that high intake of red and processed meats, highly refined grains and starches, and sugars is related to increased risk of colorectal cancer. Replacing these factors with poultry, fish, and plant sources as the primary source of protein; unsaturated fats as the primary source of fat; and unrefined grains, legumes and fruits as the primary source of carbohydrates is likely to lower risk of colorectal cancer. Although a role for supplements, including vitamin D, folate, and vitamin B6, remains uncertain, calcium supplementation is likely to be at least modestly beneficial. With respect to lifestyle, compelling evidence indicates that avoidance of smoking and heavy alcohol use, prevention of weight gain, and maintenance of a reasonable level of physical activity are associated with markedly lower risks of colorectal cancer. Medications such as aspirin and nonsteroidal anti-inflammatory drugs and postmenopausal hormones for women are associated with substantial reductions in colorectal cancer risk, though their utility is affected by associated risks. Taken together, modifications in diet and lifestyle should substantially reduce the risk of colorectal cancer and could complement screening in reducing colorectal cancer incidence.

A case-control study of levothyroxine and the risk of colorectal cancer

Levothyroxine is a synthetic T(4) hormone commonly used to treat thyroid disease. Increased incidence of mostly autoimmune thyroid disease has been associated with breast and other malignancies, and thyroid hormone levels might also be associated with risk of colorectal cancer (CRC). In this population-based matched case-control study (2566 pairs) of CRC in northern Israel, use of levothyroxine for at least 5 years was assessed using structured interviews and validated by prescription records. The analysis included use of statins, aspirin, and hormone replacement therapy; CRC family history; physical activity; vegetable consumption; ethnicity; age; and sex. All statistical tests were two-sided. The use of levothyroxine was associated with a statistically significantly reduced relative risk of CRC (odds ratio = 0.59, 95% confidence interval = 0.43 to 0.82, P = .001). This association remained statistically significant after adjustment for age, sex, use of aspirin and statins, sports activity, family history of CRC, ethnic group, and level of vegetable consumption (odds ratio = 0.60, 95% confidence interval = 0.44 to 0.81, P = .001). No statistically significant interactions were seen between use of levothyroxine and aspirin, statins, or hormone replacement therapy.

Colorectal cancer incidence and postmenopausal hormone use by type, recency, and duration in cancer prevention study II

The Women's Health Initiative randomized trials showed a reduction in colorectal cancer risk with the use of estrogen plus progesterone (E + P), but not with estrogen alone (E-only), after intervention periods <7 years. Using data from the Cancer Prevention Study II Nutrition Cohort, we examined associations of colorectal cancer risk with E-only and E + P, including analyses by recency and duration of hormone use. During 13.2 years of follow-up, 776 cases of invasive colorectal cancer occurred among 67,412 postmenopausal women participants. Cox proportional hazards models were used to estimate multivariate-adjusted relative risks (RR) and 95% confidence intervals (95% CI) of colorectal cancer for current and former hormone users according to hormone type and duration of use. Relative to women who never used postmenopausal hormones, current, but not former, use of E-only was associated with a reduced risk of colorectal cancer (RR 0.76; 95% CI, 0.59-0.97). Among current E-only users, duration of use was inversely and linearly associated with risk (P(trend) = 0.01). Use of E-only for <5 years was not associated with reduced risk, whereas use for >or=20 years was associated with a 45% reduction in risk (RR, 0.55; 95% CI, 0.36-0.86). There were no statistically significant associations between E + P and colorectal cancer risk. Our results suggest a strong inverse association of long-term use of E-only with colorectal cancer risk, underscoring the importance of collecting data on duration of hormone use in epidemiologic studies of postmenopausal hormones and risk of disease.

Use of hormone replacement therapy and the risk of colorectal cancer

PURPOSE

Estrogen/progestin replacement therapy is prescribed to women in menopause for purposes of postmenopausal symptom control or prevention of hormone deficiency-related diseases such as osteoporosis. Such treatments have formerly been shown to be associated with lower colorectal cancer risk in an as yet unknown mechanism.

PATIENTS AND METHODS

The Molecular Epidemiology of Colorectal Cancer study was a population-based case-control study in northern Israel of patients with colorectal cancer who were diagnosed between 1998 and 2006, and age-, sex-, clinic-, and ethnicity-matched population controls. Use of hormone replacement therapy (HRT) was assessed using a structured interview and validated by studying prescription records in a subset of patients for whom they were available.

RESULTS

Two thousand four hundred sixty peri/postmenopausal women were studied from among 2,648 patients with colorectal cancer and 2,566 controls. The self-reported use of HRT was associated with a significantly reduced relative risk of colorectal cancer (odds ratio [OR], 0.67; 95% CI, 0.51 to 0.89). This association remained significant after adjustment for age, sex, use of aspirin and statins, sports activity, family history of colorectal cancer, ethnic group, and level of vegetable consumption (OR, 0.37; 95% CI, 0.22 to 0.62). Statistically significant interactions were seen between use of HRT and use of aspirin and involvement in sports activity. Using pharmacy data, only users of combined oral preparations demonstrated a significant negative association with colorectal cancer.

CONCLUSION

The use of oral HRT was associated with a 63% relative reduction in the risk of colorectal cancer in postmenopausal women after adjustment for other known risk factors. This effect was not found in aspirin users and women with intensive sports participation.

The relationship between gravidity and parity and colorectal cancer risk

OBJECTIVES

The influence of hormonal changes caused by pregnancy has been well studied in relation to colorectal cancer risk, but the association remains undefined. The purpose of this investigation was to examine in a case-control study the relationship between differences in gravidity and parity and colorectal cancer risk and if the association varied by microsatellite instability (MSI), a feature more common in women.

METHODS

The study population included incident colorectal cancer patients (n = 1014), aged 50-74 years, diagnosed in 1998-2002 in Washington state and controls (n = 1064) randomly selected from population lists. All study subjects completed telephone interviews to ascertain prior pregnancies, live births, and other covariates. Case tissue samples were obtained for MSI analyses. Multivariable logistic regression models estimated odds ratios (OR) and 95% confidence intervals (CI), adjusting for age, family history of colorectal cancer, body mass index (BMI), education, endoscopy screening, oral contraceptive use, hormone therapy use, smoking, and alcohol consumption.

RESULTS

There was an approximate 30%-50% reduction in risk of colon cancer associated with gravidity, which was attenuated in the analysis with parity. Increasing gravidity and parity were associated with a suggestion of a decreasing trend in risk for rectal cancer (p for trend = 0.07). Compared with women who had equal numbers of pregnancies and live births, women who were nulligravid and nulliparous had a 40%-60% increased risk of colon cancer. There was a suggestion of a reduced risk of both colon and rectal cancer associated with one more pregnancy than live birth. There was a suggestion of an increased risk of MSI-high tumors with nulligravidity and nulliparity.

CONCLUSIONS

These results confirm the importance of pregnancy events in the etiology of colon and rectal cancer.

Menopausal hormone therapy and risk of colorectal cancer

We evaluated colorectal cancer risk associated with the duration and recency of specific menopausal hormone therapy formulations (i.e., unopposed estrogen versus estrogen plus progestin) and regimens (i.e., sequential versus continuous estrogen plus progestin use) among 56,733 postmenopausal women participating in the Breast Cancer Detection Demonstration Project follow-up study. Hormone therapy use and other risk factors were ascertained through telephone interviews and mailed questionnaires from 1979 to 1998. The final cancer group included 960 women who were identified from self-report, medical records, state registry data, and the National Death Index. Poisson regression was used to generate multivariable rate ratios (RR) and 95% confidence intervals (95% CI). We observed a decreased risk of colorectal cancer among ever users of unopposed estrogen therapy (RR, 0.83; 95% CI, 0.70-0.99). Among estrogen users, the largest reduced risk was observed for current users (RR, 0.75; 95% CI, 0.54-1.05) and users of >or=ten years duration (RR, 0.74; 95% CI, 0.56-0.96). We found a reduced risk among users of estrogen plus progestin therapy (RR, 0.78; 95% CI, 0.60-1.02), with sequential regimen users (progestin <15 days per cycle) having the largest risk reduction (RR, 0.64; 95% CI, 0.43-0.95). Past users of >or=5 years ago (RR, 0.55; 95% CI, 0.32-0.98) had the largest risk reduction. In this study, estrogen plus progestin use, especially sequential regimen use, was associated with the largest overall reduction of colorectal cancer risk.

Estrogens, phytoestrogens and colorectal neoproliferative lesions

Epidemiological and experimental studies suggest a protective role of estrogens against colorectal cancer. This effect seems to be mediated by their binding to estrogen receptor beta (ER-beta), one of the two estrogen receptors with high affinity for these hormones. Very recently, the demonstration of an involvement of ER-beta in the development of adenomatous polyps of the colon has also been documented, suggesting the use of selective ER-beta agonists in primary colorectal cancer prevention. Phytoestrogens are plant-derived compounds that structurally and functionally act as estrogen-agonists in mammals. They are characterized by a higher binding affinity to ER-beta as compared to estrogen receptor alpha (ER-alpha), the other estrogen receptor subtype. These biological characteristics explain why the administration of phytoestrogens does not produce the classical side effects associated to estrogen administration (cerebro- and cardio-vascular accidents, higher incidence of endometrial and breast cancer) and makes these substances ideal candidates for the prevention of colorectal cancer.

Oral contraceptive use, hormone replacement therapy, reproductive history and risk of colorectal cancer in women

Evidence from epidemiologic studies suggests a possible role of exogenous and endogenous hormones in colorectal carcinogenesis in women. However, with respect to exogenous hormones, in contrast to hormone replacement therapy, few cohort studies have examined oral contraceptive use in relation to colorectal cancer risk. We used data from a large cohort study of Canadian women enrolled in a randomized controlled trial of breast cancer screening to assess the association of oral contraceptive use, hormone replacement therapy and reproductive factors with risk of colorectal cancer, overall and by subsite within the colorectum. Cancer incidence and mortality were ascertained by linkage to national databases. Among 89,835 women aged 40-59 at enrollment and followed for an average of 16.4 years, we identified 1,142 incident colorectal cancer cases. Proportional hazards models were used to estimate the associations between the exposures of interest and risk of colorectal cancer. Ever use of oral contraceptives at baseline was associated with a modest reduction in the risk of colorectal cancer (hazard ratio 0.83, 95% confidence interval 0.73-0.94), with similar effects for different subsites within the colorectum. No trend was seen in the hazard ratios with increasing duration of oral contraceptive use. No associations were seen with use of hormone replacement therapy (ever use or duration of use) or reproductive factors. Our results are suggestive of an inverse association between oral contraceptive use and colorectal carcinogenesis. However, given the lack of a dose-response relationship and the potential for confounding, studies with more complete assessment of exogenous hormone use throughout the life course are needed to clarify this association.

Molecular markers and targets for colorectal cancer prevention

Colorectal cancer is the third most prevalent cancer in the world. If detected at an early stage, treatment often might lead to cure. As prevention is better than cure, epidemiological studies reveal that having a healthy diet often protects from promoting/ developing cancer. An important consideration in evaluating new drugs and devices is determining whether a product can effectively treat a targeted disease. There are quite a number of biomarkers making their way into clinical trials and few are awaiting the preclinical efficacy and safety results to enter into clinical trials. Researchers are facing challenges in modifying trial design and defining the right control population, validating biomarker assays from the biological and analytical perspective and using biomarker data as a guideline for decision making. In spite of following all guidelines, the results are disappointing from many of the large clinical trials. To avoid these disappointments, selection of biomarkers and its target drug needs to be evaluated in appropriate animal models for its toxicities and efficacies. The focus of this review is on the few of the potential molecular targets and their biomarkers in colorectal cancers. Strengths and limitations of biomarkers/surrogate endpoints are also discussed. Various pathways involved in tumor cells and the specific agents to target the altered molecular biomarker in biomolecular pathway are elucidated. Importance of emerging new platforms siRNAs and miRNAs technology for colorectal cancer therapeutics is reviewed.

Pregnancy does not influence colonic polyp multiplicity but may modulate upper gastrointestinal disease in patients with FAP

BACKGROUND

Reproductive factors have been shown by epidemiology studies to alter colorectal cancer risk in women. Familial adenomatous polyposis (FAP) patients carry a germline adenomatous polyposis coli (APC) mutation predisposing to multiple adenoma formation in the intestine. The Min mouse provides a good model of FAP, and we recently reported a significant increase in intestinal tumour multiplicity in a recombinant line of mice following pregnancy.

AIM

We considered whether reproduction modulates intestinal tract disease in a large cohort of female patients with FAP (n = 180).

RESULTS

Multiple regression analysis showed that the number of colonic polyps observed was not related to the person's pregnancy status nor the position of their APC germline mutation. The proportion of women attaining a high Spigelman stage (3 or 4) was unrelated to having a pregnancy prior to attaining the maximum Spigelman stage (p = 0.6). On the other hand, having a pregnancy significantly increased the proportion of women that attained the highest Spigelman stage when their APC germline mutation occurred within the mutation cluster region or at or after codon 1020 (50%, 6/12, p = 0.005 and 42%, 13/31, p = 0.006, respectively; multivariable logistic regression).

CONCLUSION

Our data suggest that reproduction may influence disease severity in the upper gastrointestinal tract in patients with FAP.

Exogenous hormones and colorectal cancer risk in Canada: associations stratified by clinically defined familial risk of cancer

OBJECTIVE

This work assessed associations between colorectal cancer risk and postmenopausal/contraceptive hormones; subgroup analyses included women with a clinically defined family history of cancer.

METHODS

A population based case-control study of incident colorectal cancer was conducted among women aged 20-74 years in Ontario and Newfoundland & Labrador, Canada. Incident cases (n = 1,404) were selected from provincial cancer registries and controls (n = 1,203) were identified through property records, and other means, between January 1997 and April 2006. Family history of cancer, exogenous hormone-use, and other risk factors were collected via self-administered questionnaires. Multivariate unconditional logistic regression analyses were used to estimate odds ratios (ORs) and corresponding 95% confidence intervals (CIs).

RESULTS

Decreased risks of colorectal cancer were observed with ever-users of: hormonal contraceptives (OR: 0.77; CI: 0.65-0.91), estrogen-only postmenopausal hormones (OR: 0.60; CI: 0.47-0.75), and estrogen-progestin postmenopausal hormones (OR: 0.70; CI: 0.52-0.95). Risk estimates were similar between women with and without a strong familial history of cancer. Age at initiation of hormonal contraceptives was associated with colorectal cancer risk; women who initiated use at younger ages (age <22 years: OR: 0.60; CI: 0.47-0.77) experienced a greater reduced risk of disease than women who initiated use at later ages (age 30+: OR: 0.92; CI: 0.68-1.24; p (trend): 0.0026).

CONCLUSIONS

These results indicate that exogenous hormone-use is linked with reduced risk of colorectal cancer among women with a strong familial risk of cancer, consistent with observations on population samples of sporadic colorectal cancer cases. A potential age-effect for use of hormonal contraceptives warrants further attention.

Physical activity and colon cancer risk among women in the California Teachers Study

BACKGROUND

Existing data suggest that physical activity reduces colon cancer risk, but the association is not consistently observed in women. One potential explanation for this inconsistency is that hormone therapy, which is associated with lower colon cancer risk, acts as a modifier of the physical activity/colon cancer relationship.

METHODS

Participants in the California Teachers Study (N = 120,147), a prospective cohort of female teachers and administrators residing in California, ages 22 to 84 years at baseline and with no prior history of colon cancer were eligible for study. Between 1996 and 2002, 395 patients were diagnosed with invasive colon cancer. The relative risks (RR) associated with lifetime (high school through age 54 years or current age) and recent (past 3 years) strenuous and moderate recreational physical activity were estimated using Cox proportional hazards regression models.

RESULTS

Combined lifetime moderate and strenuous recreational physical activity was only modestly associated with colon cancer risk in the cohort [>or=4 versus <or=0.5 h/wk/y: RR, 0.75; 95% confidence interval, 0.57-1.00; P(trend) = 0.23]. Lifetime physical activity reduced colon cancer risk among postmenopausal women who had never taken hormone therapy (>or=4 versus <or=0.5 h/wk/y: RR, 0.51; 95% confidence interval, 0.31-0.85; P(trend) = 0.02). Postmenopausal women with histories of hormone therapy use had lower colon cancer risk, but their risk was not associated with physical activity. The likelihood ratio test for interaction between hormone use and lifetime moderate plus strenuous physical activity was of borderline statistical significance (P = 0.05). We observed no effect modification by age, body mass index, smoking status, menopausal status, or folate intake.

CONCLUSIONS

Lifetime recreational physical activity may protect against colon cancer among postmenopausal women who have never used hormone therapy. Among hormone therapy users, who have lower risk of colon cancer, recreational physical activity does not seem to provide any additional benefit. With declining rates of hormone therapy use, physical activity offers one possible means for reducing women's colon cancer risk.

The interaction of age and hormone replacement therapy on colon adenoma risk

BACKGROUND

Several studies have identified a possible interaction between age and hormone replacement therapy on colon neoplasm risk. We re-evaluated this interaction and determined if this interaction may be explained by the longer duration of estrogen use in older, rather than younger, women.

METHODS

Included in the case-control study were 755 women (169 cases and 586 controls.) who were recruited from patients with no prior history of colorectal neoplasm and undergoing an elective colonoscopy examination.

RESULTS

There was a significant interaction between age and hormone replacement therapy use (P=0.03) with current estrogen users who were over 56 years of age having a reduced odds of colon adenoma (OR, 0.40; 95% CI, 0.16-0.98) when compared to never users. Both older women who had used hormone replacement therapy for 3 or less years (OR, 0.07; 95% CI, 0.006-0.81) and those reporting greater than 10 years of use (OR, 0.27; 95% CI, 0.09-0.80) had a reduced adjusted odds for adenomas when compared to non-users. No apparent association with estrogen replacement therapy was found among younger women (<56 years).

CONCLUSIONS

Duration of use is not likely to explain the stronger association of hormone replacement therapy use with colon neoplasm in older women. Additional work is needed to better characterize the underlying mechanisms associated with this interaction.