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

Risk of colorectal cancer after use of fertility drugs-results from a large Danish population-based cohort of women with infertility

OBJECTIVE

To study the association between use of fertility drugs and colorectal cancer among women with infertility.

DESIGN

Population-based cohort study.

SETTING

Not applicable.

PATIENT(S)

The study cohort was obtained from the Danish Infertility Cohort and consisted of all women with infertility aged 20-45 years living in Denmark during 1995-2017.

INTERVENTION(S)

Information on the use of specific types of fertility drugs, colorectal cancer diagnoses, covariates, and vital status were obtained from the Danish Infertility Cohort and Danish national registers.

MAIN OUTCOME MEASURE(S)

Cox proportional hazard models adjusted for potential confounders were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for colorectal cancer overall and rectal and colon cancer separately.

RESULTS(S)

Among 148,036 women in the final study cohort, 205 women were diagnosed with colorectal cancer. Ever use of clomiphene citrate (CC) was associated with a lower rate of colorectal cancer (unadjusted HR, 0.67; 95% CI, 0.51-0.89; adjusted HR, 0.68; 95% CI, 0.50-0.93). However, the lower rate was only seen among women who first used CC >8 years ago (unadjusted HR, 0.56; 95% CI, 0.41-0.76; adjusted HR, 0.52; 95% CI, 0.36-0.75). No marked associations were found between the use of any of other types of fertility drugs and colorectal cancer. The results for colon and rectal cancer analyzed separately were similar, except for a suggestion of a decreased risk of rectal cancer associated with the use of gonadotropins (adjusted HR, 0.46; 95% CI, 0.20-1.08).

CONCLUSION(S)

Among women with infertility, the use of most types of fertility drugs was not associated with colorectal cancer. However, CC may decrease the risk of colorectal cancer and gonadotropins might decrease the risk of rectal cancer, but we cannot rule out that these findings may be more related to the underlying conditions in these women or are chance findings. Consequently, the results from this study should be investigated further in large epidemiological studies.

Therapeutic Strategies and Potential Actions of Female Sex Steroid Hormones and Their Receptors in Colon Cancer Based on Preclinical Studies

Several epidemiological studies have reported that the use of female sex steroid hormones could reduce the risk of colon cancer (CRC). This review summarizes the available data related to estradiol (E2) and progesterone (P4) single and dual treatments in CRC male and female in vitro and in vivo models, mainly from preclinical studies, alongside their potential molecular mechanisms. Most of the studies showed that E2 exogenous treatment and/or reactivation of its beta receptor (ERβ) significantly inhibited cell proliferation, induced cell cycle arrest, and promoted apoptosis by modulating several molecular pathways. Likewise, the inhibition of ERα receptors produced similar antitumorigenic actions, both in vivo and in vitro, suggesting that E2 could have dual opposing roles in CRC that are dependent on the expression profile of its nuclear receptors. The available studies on P4 are scarce, and the results revealed that in vitro and in vivo treatments with natural and synthetic progesterone were also associated with promising tumoricidal actions. Nevertheless, the combination of E2 with P4 showed enhanced anticancer activities compared with their monotherapy protocols in male–female cell lines and animals. Collectively, the studies suggested that the female sex steroid hormones could provide a novel and effective therapeutic strategy against CRC.

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.

Body Weight, Physical Activity, and Risk of Cancer in Lynch Syndrome

Lynch syndrome (LS) increases cancer risk. There is considerable individual variation in LS cancer occurrence, which may be moderated by lifestyle factors, such as body weight and physical activity (PA). The potential associations of lifestyle and cancer risk in LS are understudied. We conducted a retrospective study with cancer register data to investigate associations between body weight, PA, and cancer risk among Finnish LS carriers. The participants (n = 465, 54% women) self-reported their adulthood body weight and PA at 10-year intervals. Overall cancer risk and colorectal cancer (CRC) risk was analyzed separately for men and women with respect to longitudinal and near-term changes in body weight and PA using extended Cox regression models. The longitudinal weight change was associated with an increased risk of all cancers (HR 1.02, 95% CI 1.00-1.04) and CRC (HR 1.03, 1.01-1.05) in men. The near-term weight change was associated with a lower CRC risk in women (HR 0.96, 0.92-0.99). Furthermore, 77.6% of the participants retained their PA category over time. Men in the high-activity group had a reduced longitudinal cancer risk of 63% (HR 0.37, 0.15-0.98) compared to men in the low-activity group. PA in adulthood was not associated with cancer risk among women. These results emphasize the role of weight maintenance and high-intensity PA throughout the lifespan in cancer prevention, particularly in men with LS.

Postmenopausal Hormone Therapy and Colorectal Cancer Risk by Molecularly Defined Subtypes and Tumor Location

BACKGROUND

Postmenopausal hormone therapy (HT) is associated with a decreased colorectal cancer (CRC) risk. As CRC is a heterogeneous disease, we evaluated whether the association of HT and CRC differs across etiologically relevant, molecularly defined tumor subtypes and tumor location.

METHODS

We pooled data on tumor subtypes (microsatellite instability status, CpG island methylator phenotype status, BRAF and KRAS mutations, pathway: adenoma-carcinoma, alternate, serrated), tumor location (proximal colon, distal colon, rectum), and HT use among 8220 postmenopausal women (3898 CRC cases and 4322 controls) from 8 observational studies. We used multinomial logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CIs) for the association of ever vs never HT use with each tumor subtype compared with controls. Models were adjusted for study, age, body mass index, smoking status, and CRC family history. All statistical tests were 2-sided.

RESULTS

Among postmenopausal women, ever HT use was associated with a 38% reduction in overall CRC risk (OR =0.62, 95% CI = 0.56 to 0.69). This association was similar according to microsatellite instability, CpG island methylator phenotype and BRAF or KRAS status. However, the association was attenuated for tumors arising through the serrated pathway (OR = 0.81, 95% CI = 0.66 to 1.01) compared with the adenoma-carcinoma pathway (OR = 0.63, 95% CI = 0.55 to 0.73; P het =.04) and alternate pathway (OR = 0.61, 95% CI = 0.51 to 0.72). Additionally, proximal colon tumors had a weaker association (OR = 0.71, 95% CI = 0.62 to 0.80) compared with rectal (OR = 0.54, 95% CI = 0.46 to 0.63) and distal colon (OR = 0.57, 95% CI = 0.49 to 0.66; P het =.01) tumors.

CONCLUSIONS

We observed a strong inverse association between HT use and overall CRC risk, which may predominantly reflect a benefit of HT use for tumors arising through the adenoma-carcinoma and alternate pathways as well as distal colon and rectal tumors.

Association of Combined Estrogen-Progestogen and Progestogen-Only Contraceptives with the Development of Cancer

Combined estrogen-progestogen contraceptives (oral contraceptives or OCs) and progestogen-only contraceptives (POCs) are synthetic steroids that bind to steroid hormone receptors, which are widespread throughout the body. They have a profound effect on cellular physiology. Combined OCs have been classified by the International Agency for Research on Cancer (IARC) as Group 1 carcinogens, but their findings have not been updated recently. In order to update the information and better understand the impact that OCs and POCs have on the risk of development of cancers, a comprehensive literature search was undertaken, focusing on more recently published papers. In agreement with the IARC, the recent literature confirms an increased risk of breast cancer and cervical cancer with the use of OCs. The recent literature also confirms the IARC conclusion that OCs decrease the risk of ovarian and endometrial cancers. However, there is little support from recent studies for the IARC conclusion that OCs decrease the risk of colorectal cancer or increase the risk of liver cancer. For liver cancer, this may be due to the recent studies having been performed in areas where hepatitis is endemic. In one large observational study, POCs also appear to increase the overall risk of developing cancer. OCs and POCs appear to increase the overall risk of cancer when carefully performed studies with the least intrinsic bias are considered.

Summary

OCs have been classified as cancer-causing agents, especially leading to increases in breast cancer and cervical cancer. A review of the recent scientific literature was performed to see whether this still appears to be the case. The recent literature supports the cancer-causing role of OCs especially for breast cancer and cervical cancer. Studies also indicate that progesterone-only contraceptives (such as implants and vaginal rings) also can cause cancer. This is especially true for breast cancer and cervical cancer.

Do the Fertility Drugs Increase the Risk of Cancer? A Review Study

Aim: All over the world, many couples cannot conceive a child and have problems with pregnancy. Ovulation-inducing drugs are among the most important drugs used for the treatment of infertility. In recent years, there have been many debates about the relationship between fertility medication and cancer. Due to the lack of comprehensive study of this matter, and as understanding the relationship between the use of fertility drugs and cancer is of importance, the present study was conducted to investigate the relationship between infertility drugs and cancer in women. Materials and Methods: To determine the relationship between infertility treatment and cancer, a comprehensive search was carried out in databases such as; Medline, Web of Science Core Collection, and Scopus using keywords words; "infertility," "ovulation induction," "cancer," "infertility treatment," "ART," "tumor," "controlled ovarian stimulation," "fertility agents," and "neoplasms." Full-text, English language, and original articles were included in this study. Results: In total, 81 articles were entered into the study. The relationship between fertility medications and breast, ovary, endometrial, uterus, colon, thyroid, skin, cervical, and non-Hodgkin's lymphoma cancers were studied. Although the relationship between fertility medications and cancer is theoretically justifiable, most studies have shown that risk of cancer will not increase after fertility treatment. Conclusion: The results of this study did not show that fertility medications increase the risk of cancer among users. In summary, the relationship between infertility treatment and cancer incidence remains an open question.

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.

CYP24A1 variant modifies the association between use of oestrogen plus progestogen therapy and colorectal cancer risk

BACKGROUND

Menopausal hormone therapy (MHT) use has been consistently associated with a decreased risk of colorectal cancer (CRC) in women. Our aim was to use a genome-wide gene-environment interaction analysis to identify genetic modifiers of CRC risk associated with use of MHT.

METHODS

We included 10 835 postmenopausal women (5419 cases and 5416 controls) from 10 studies. We evaluated use of any MHT, oestrogen-only (E-only) and combined oestrogen-progestogen (E+P) hormone preparations. To test for multiplicative interactions, we applied the empirical Bayes (EB) test as well as the Wald test in conventional case-control logistic regression as primary tests. The Cocktail test was used as secondary test.

RESULTS

The EB test identified a significant interaction between rs964293 at 20q13.2/CYP24A1 and E+P (interaction OR (95% CIs)=0.61 (0.52-0.72), P=4.8 × 10(-9)). The secondary analysis also identified this interaction (Cocktail test OR=0.64 (0.52-0.78), P=1.2 × 10(-5) (alpha threshold=3.1 × 10(-4)). The ORs for association between E+P and CRC risk by rs964293 genotype were as follows: C/C, 0.96 (0.61-1.50); A/C, 0.61 (0.39-0.95) and A/A, 0.40 (0.22-0.73), respectively.

CONCLUSIONS

Our results indicate that rs964293 modifies the association between E+P and CRC risk. The variant is located near CYP24A1, which encodes an enzyme involved in vitamin D metabolism. This novel finding offers additional insight into downstream pathways of CRC etiopathogenesis.

Effects of fertility drugs on cancers other than breast and gynecologic malignancies

OBJECTIVE

To examine the relationship of ovulation-stimulating drugs to risk of cancers other than breast and gynecologic malignancies.

DESIGN

Retrospective cohort study, with additional follow-up since initial report.

SETTING

Reproductive endocrinology practices.

PATIENT(S)

Among a cohort of 12,193 women evaluated for infertility between 1965 and 1988, a total of 9,892 women (81.1% of the eligible population) were followed through 2010, via passive and active (questionnaire) approaches.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Hazard ratios (HRs) and 95% confidence intervals (CIs) for various fertility treatment parameters for select cancers.

RESULT(S)

During 30.0 median years of follow-up (285,332 person-years), 91 colorectal cancers, 84 lung cancers, 55 thyroid cancers, and 70 melanomas were diagnosed among study subjects. Clomiphene citrate (CC), used by 38.1% of patients, was not associated with colorectal or lung cancer risks, but was related significantly to melanoma (HR = 1.95; 95% CI: 1.18-3.22), and non-significantly to thyroid cancer risks (HR = 1.57; 95% CI: 0.89-2.75). The highest melanoma risks were seen among those with the lowest drug exposure levels, but thyroid cancer risk was greatest among the heavily exposed patients (HR = 1.96; 95% CI: 0.92-4.17 for those receiving >2,250 mg). Clomiphene citrate-associated risks for thyroid cancer were somewhat higher among nulligravid, compared with gravid, women, but did not differ according to distinct causes of infertility. Gonadotropins, used by only 9.7% of subjects, were not related to risk of any of the assessed cancers.

CONCLUSION(S)

Our results provide support for continued monitoring of both melanoma and thyroid cancer risk among patients receiving fertility drugs.

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.

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.

Associations of hormone replacement therapy and oral contraceptives with risk of colorectal cancer defined by clinicopathological factors, beta-catenin alterations, expression of cyclin D1, p53, and microsatellite-instability

Background

Postmenopausal hormone therapy (HRT) and oral contraceptive (OC) use have in several studies been reported to be associated with a decreased colorectal cancer (CRC) risk. However, data on the association between HRT and OC and risk of different clinicopathological and molecular subsets of CRC are lacking. The aim of this molecular pathological epidemiology study was therefore to evaluate the associations between HRT and OC use and risk of specific CRC subgroups, overall and by tumour site.

Method

In the population-based prospective cohort study Mamö Diet and Cancer, including 17035 women, 304 cases of CRC were diagnosed up until 31 December 2008. Immunohistochemical expression of beta-catenin, cyclin D1, p53 and MSI-screening status had previously been assessed in tissue microarrays with tumours from 280 cases. HRT was assessed as current use of combined HRT (CHRT) or unopposed oestrogen (ERT), and analysed among 12583 peri-and postmenopausal women. OC use was assessed as ever vs never use among all women in the cohort. A multivariate Cox regression model was applied to determine hazard ratios for risk of CRC, overall and according to molecular subgroups, in relation to HRT and OC use.

Results

There was no significantly reduced risk of CRC by CHRT or ERT use, however a reduced risk of T-stage 1–2 tumours was seen among CHRT users (HR: 0.24; 95% CI: 0.09-0.77).

Analysis stratified by tumour location revealed a reduced overall risk of rectal, but not colon, cancer among CHRT and ERT users, including T stage 1–2, lymph node negative, distant metastasis-free, cyclin D1 - and p53 negative tumours.

In unadjusted analysis, OC use was significantly associated with a reduced overall risk of CRC (HR: 0.56; 95% CI: 0.44-0.71), but this significance was not retained in adjusted analysis (HR: 1.05: 95% CI: 0.80-1.37). A similar risk reduction was seen for the majority of clinicopathological and molecular subgroups.

Conclusion

Our findings provide information on the relationship between use of HRT and OC and risk of clinicopathological and molecular subsets of CRC.

Oral contraceptive use and risk of breast, cervical, colorectal, and endometrial cancers: a systematic review

Oral contraceptives may influence the risk of certain cancers. As part of the AHRQ Evidence Report, Oral Contraceptive Use for the Primary Prevention of Ovarian Cancer, we conducted a systematic review to estimate associations between oral contraceptive use and breast, cervical, colorectal, and endometrial cancer incidence. We searched PubMed, Embase, and Cochrane Database of Systematic Reviews. Study inclusion criteria were women taking oral contraceptives for contraception or ovarian cancer prevention; includes comparison group with no oral contraceptive use; study reports quantitative associations between oral contraceptive exposure and relevant cancers; controlled study or pooled patient-level meta-analyses; sample size for nonrandomized studies ≥100; peer-reviewed, English-language; published from January 1, 2000 forward. Random-effects meta-analyses were conducted by estimating pooled ORs with 95% confidence intervals (CIs). We included 44 breast, 12 cervical, 11 colorectal, and 9 endometrial cancers studies. Breast cancer incidence was slightly but significantly increased in users (OR, 1.08; CI, 1.00-1.17); results show a higher risk associated with more recent use of oral contraceptives. Risk of cervical cancer was increased with duration of oral contraceptive use in women with human papillomavirus infection; heterogeneity prevented meta-analysis. Colorectal cancer (OR, 0.86; CI, 0.79-0.95) and endometrial cancer incidences (OR, 0.57; CI, 0.43-0.77) were significantly reduced by oral contraceptive use. Compared with never use, ever use of oral contraceptives is significantly associated with decreases in colorectal and endometrial cancers and increases in breast cancers. Although elevated breast cancer risk was small, relatively high incidence of breast cancers means that oral contraceptives may contribute to a substantial number of cases.

Cancer incidence and mortality trends in Australian adolescents and young adults, 1982-2007

Background

Increasing incidence and lack of survival improvement in adolescents and young adults (AYAs) with cancer have led to increased awareness of the cancer burden in this population. The objective of this study was to describe overall and type-specific cancer incidence and mortality trends among AYAs in Western Australia from 1982–2007.

Methods

Age–adjusted incidence and mortality rates were calculated for all malignancies combined and for each of the most common diagnostic groups, using five-year age–specific rates. Joinpoint regression analysis was used to derive annual percentage changes (APC) for incidence and mortality rates.

Results

The annual incidence rate for all cancers combined increased in males from 1982 until 2000 (APC = 1.5%, 95%CI: 0.9%; 2.1%) and then plateaued, whilst rates for females remained stable across the study period (APC = −0.1%; 95%CI: −0.2%; 0.4%) across the study period. For males, significant incidence rate increases were observed for germ cell tumors, lymphoblastic leukemia and thyroid cancer. In females, the incidence of Hodgkin’s lymphoma, colorectal and breast cancers increased. Significant incidence rate reductions were noted for cervical, central nervous system and lung cancers. Mortality rates for all cancers combined decreased from 1982 to 2005 for both males (APC = −2.6%, 95%CI:−3.3%;−2.0%) and females (APC = −4.6%, 95%CI:−5.1%;−4.1%). With the exception of bone sarcoma and lung cancer in females, mortality rates for specific cancer types decreased significantly for both sexes during the study period.

Conclusions

Incidence of certain AYA cancers increased, whilst it decreased for others. Mortality rates decreased for most cancers, with the largest improvement observed for breast carcinomas. Further research is needed to identify the reasons for the increasing incidence of certain cancers.

Postmenopausal hormone therapy is associated with a reduced risk of colorectal cancer lacking CDKN1A expression

Experimental studies have shown that estrogen- or progesterone-activated signaling leads to growth inhibition effects on colon cancer cells through the upregulation of several cell-cycle regulators. However, epidemiologic studies evaluating hormone therapy use and colorectal cancer risk by the status of cell-cycle regulators are lacking. In this study, we used data from the prospective Nurses' Health Study to evaluate whether the association between hormone therapy use and colorectal cancer risk differs by the molecular pathologic status of microsatellite instability (MSI) and expression of cell-cycle-related tumor biomarkers, including CDKN1A (p21, CIP1), CDKN1B (p27, KIP1), and TP53 (p53) by immunohistochemistry. Duplication Cox regression analysis was used to determine an association between hormone therapy use, cancer risk, and specific tumor biomarkers in 581 incident colon and rectal cancer cases that occurred during 26 years of follow-up among 105,520 postmenopausal women. We found a difference between hormone therapy use and colorectal cancer risk according to CDKN1A expression (P(heterogeneity) = 0.01). Current hormone therapy use was associated with a reduced risk for CDKN1A-nonexpressed [multivariate relative risk (RR), 0.61; 95% confidence interval (CI), 0.46-0.82] but not for CDKN1A-expressed (RR, 1.32; 95% CI, 0.76-2.31) tumors. The lower risk for CDKN1A-nonexpressed but not for CDKN1A-expressed cancers was also present among current users of estrogen-alone therapy. We found no significant difference in the relations between hormone therapy use and cancer risk according to MSI, CDKN1B, or TP53 status. Together, our molecular pathological epidemiology findings suggest a preventive effect of hormone therapy against colorectal carcinogenesis that depends, in part, on loss of cyclin-dependent kinase inhibitor CDKN1A.

Risk prediction models for colorectal cancer: a review

Risk prediction models are important to identify individuals at high risk of developing the disease who can then be offered individually tailored clinical management, targeted screening and interventions to reduce the burden of disease. They are also useful for research purposes when attempting to identify new risk factors for the disease. In this article, we review the risk prediction models that have been developed for colorectal cancer and appraise their applicability, strengths, and weaknesses. We also discuss the factors to be considered for future development and improvement of models for colorectal cancer risk prediction. We conclude that there is no model that sufficiently covers the known risk factors for colorectal cancer that is suitable for assessment of people from across the full range of risk and that a new comprehensive model is needed.

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 effect of estrogen vs. combined estrogen-progestogen therapy on the risk of colorectal cancer

Studies suggest that estrogen therapy (ET) and combined estrogen-progestogen therapy (EPT) may have different associations with colorectal cancer (CRC) risk, but data are conflicting. Prior meta-analyses did not distinguish between ET and EPT. We conducted a meta-analysis to summarize the relative risks (RR) of CRC due to ET versus EPT among peri- or postmenopausal women. From a total of 2,661 articles, four randomized controlled trials, eight cohort and eight case-control studies were included. Variables assessed included study characteristics, duration and recency of menopausal hormone therapy (HT) use, method of assessment of HT use, outcome definition and its ascertainment method. RRs were synthesized by random-effects models. We found that EPT ever use was associated with a decreased risk of CRC (RR 0.74, 95% CI 0.68-0.81), and so was ET ever use (RR 0.79, 95% CI 0.69-0.91). While current use of ET was associated with a significantly reduced risk of CRC (RR 0.70, 95% CI 0.57-0.85), former use was not (RR 0.86, 95%CI 0.67-1.11). Recency did not significantly modify the association between EPT and CRC risk. EPT former use was associated with a lower RR of CRC compared to ET former use (p = 0.008) but no such difference was observed between EPT and ET current use (p = 0.12). Overall, we found consistent evidence supporting the association between EPT and CRC risk reduction, regardless of recency. While literature for the association between ET and CRC risk is heterogeneous, our analyses suggest only current use of ET is associated with a decreased CRC risk.

Menopausal hormone therapy and risk of colorectal cancer in the European Prospective Investigation into Cancer and Nutrition

Menopausal hormone therapy (HT) may influence colorectal cancer risk. A total of 136,275 postmenopausal women from the European Prospective Investigation into Cancer and Nutrition were followed for an average of 9 years, during which time 1,186 colorectal cancers were diagnosed. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards models stratified by center and age, and adjusted for body mass index, smoking, diabetes, physical activity and alcohol consumption. Compared to never use of HT at study enrollment, current use of estrogen-only (HR, 1.02; 95% CI, 0.79-1.31) or estrogen plus progestin (HR, 0.94; 95% CI, 0.77-1.14) was not significantly associated with the risk of colorectal cancer, and these associations did not vary by recency, duration, route of administration, regimen or specific constituent of HT. Our results show no significant association of estrogen-only or estrogen plus progestin therapy with colorectal cancer risk.

Tobacco smoking and colorectal cancer: a population-based case-control study in Newfoundland and Labrador

OBJECTIVE

Newfoundland and Labrador (NL) has the highest incidence rate of both colorectal cancer (CRC) and smoking prevalence in Canada. The objective of this study was to examine if CRC is associated with smoking in this population.

METHODS

Newly diagnosed cases identified between 1999 and 2003 were frequency-matched by 5-year age group and sex with controls selected from the residents of NL through random digit dialing. A total of 702 cases and 717 controls consented to participate in the study and completed a set of self-administered questionnaires. Measures of tobacco use included type of tobacco, age of initiation of smoking, years of smoking, years since started smoking, number of cigarettes smoked daily, pack years, and years since abstention from smoking. Odds ratios were estimated using multivariate logistic regression.

RESULTS

In comparison with non-smokers, former and current smokers were at a significantly elevated risk of CRC with corresponding odds ratios of 1.36 and 1.96. The risk significantly increased with cigarette smoking years, the amount of cigarettes smoked daily, and cigarette pack years. The risk significantly decreased with years of abstention from smoking cigarettes. This association was stronger among drinkers and in men. In addition, this effect was observed to be slightly stronger for rectum than colon cancer.

DISCUSSION

In summary, cigarette smoking increased the risk of CRC in the NL population. The risk of CRC associated with cigarette smoking varies by sex, drinking status, and site of CRC.

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.

Should transdermal rather than oral estrogens be used in menopausal hormone therapy? A review

The current evaluation of the benefit/risk ratio associated with menopausal hormone therapy (MHT) use is largely based on clinical trials which investigated the effects of oral treatments. Would MHT with transdermal estrogens be associated with a more favourable benefit/risk ratio? We reviewed the available epidemiologic evidence on that question. Epidemiologic studies were considered if they provided risk estimates of conditions which carry an important weight among menopausal women, and for which epidemiologic evidence of a possible link with MHT use is convincing: cardiovascular diseases, breast cancer, diabetes, colorectal cancer and hip fracture. We did not include studies with only surrogate measures. We found that the available information on the potential impact of the route of administration of MHT on the risk of our selected outcomes is limited. To date, epidemiologic data suggest that it has no impact on the risk of breast cancer and hip fracture. Results on the risk of coronary heart disease and colorectal cancer are inconsistent. Studies on stroke and diabetes risk are too few to allow meaningful conclusions. There is a suggestion that transdermal MHT may be less deleterious than oral MHT regarding venous thromboembolism which needs to be confirmed. The issue of the route of administration of MHT should remain an active area of research as part of an attempt to identify treatment modalities that would have the least potential for exerting adverse effects.

Hormone therapy, DNA methylation and colon cancer

Observational epidemiological studies and randomized trials have reported a protective effect of estrogen and progestin therapy (EPT) on the risk of colorectal cancer but the findings on estrogen-alone therapy (ET) are less consistent. The mechanism by which menopausal hormones influence risk of colorectal cancer has not been well studied. To further investigate the relationship between menopausal hormones and risk of colon cancer, we conducted a population-based case-control study in Los Angeles County involving 831 women with newly diagnosed colon cancer and 755 population-based control women. Risk of colon cancer decreased significantly with increasing duration of current use of ET and EPT; the adjusted relative risk was 0.83 [95% confidence interval (95% CI) = 0.76-0.99)] per 5 years of ET use and 0.88 (95% CI = 0.78-0.99) per 5 years of EPT use. Risk of colon cancer was unrelated to past ET or EPT use. We explored if current use of menopausal hormones is associated with DNA methylation of estrogen receptor (ESR1 and ESR2), progesterone receptor and other genes in the colonic tissues of a subset of colon cancer patients (n = 280) we interviewed. Our results suggest that current menopausal hormone users compared with non-current users displayed increased DNA methylation of progesterone receptor in the 'normal' colonic tissues (P = 0.055) and increased DNA methylation of ESR1 in the 'tumorous' colonic tissues (P = 0.056). These findings on DNA methylation and hormone therapy use need confirmation in larger studies.

Menopausal hormone therapy use and risk of invasive colon cancer: the California Teachers Study

Results from epidemiologic studies of hormone therapy use and colon cancer risk are inconsistent. This question was investigated in the California Teachers Study (1995-2006) among 56,864 perimenopausal or postmenopausal participants under 80 years of age with no prior colorectal cancer by using Cox proportional hazards regression. Incident invasive colon cancer was diagnosed among 442 participants. Baseline-recent hormone therapy users were at 36% lower risk for colon cancer versus baseline-never users (baseline-recent users: relative risk (RR) = 0.64, 95% confidence interval (CI): 0.51, 0.80). Results did not differ by formulation. Estimated risk was lower among baseline-recent hormone therapy users with increasing duration between 5 and 15 years of use (RR = 0.49, 95% CI: 0.35, 0.68), but the trend did not persist in the longest duration group, more than 15 years of use (RR = 0.69, 95% CI: 0.52, 0.92; P(trend) = 0.60). Long-term recreational physical activity, obesity, regular use of nonsteroidal antiinflammatory medications, and daily alcohol intake did not modify these effects; baseline-recent use was more strongly associated with colon cancer risk among women with a family history of colorectal cancer (P(heterogeneity) = 0.04). Baseline-recent hormone therapy use was inversely associated with invasive colon cancer risk among perimenopausal and postmenopausal women in the California Teachers Study.

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.

Family history of hormonal cancers and colorectal cancer risk: a case-control study conducted in Ontario

Aggregation of cancers among families with highly penetrant genetic mutations such as hereditary nonpolyposis colorectal cancer is well-described. However, there is a paucity of data regarding familial aggregation of hormonal cancers (cancers of the breast, endometrial, ovarian and prostate) and colorectal cancer (CRC) in the general population. We investigated the association between having a first-degree family history of breast, endometrial, ovarian, or prostate cancer and CRC risk. Population-based CRC cases and controls were recruited by the Ontario Familial Colorectal Cancer Registry (OFCCR). Logistic regression was conducted to obtain odds ratio (OR) estimates and 95% confidence intervals (95% CIs). First-degree family history of breast cancer was associated with a modest, borderline statistically significant increased CRC risk (age-, sex-adjusted OR = 1.2, 95% CI = 1.0, 1.5). The magnitude of CRC risk was greatest if more than one first-degree kin had breast cancer (age-, sex-adjusted OR = 1.7, 95% CI = 1.0, 2.0), as well as if the kin was diagnosed at >50 years of age (age-, sex-adjusted OR = 1.4, 95% CI = 1.1, 1.8). Family history of ovarian cancer was associated with reduced CRC risk (multivariate-adjusted OR = 0.6, 95% CI = 0.3, 1.0). Although statistically significant increases in CRC risk were observed in the age-, sex-adjusted OR estimates for family history of endometrial and prostate cancers, the associations were no longer significant after multivariate-adjustment. In conclusion, individuals with a first-degree kin with breast cancer may have a modest increased risk for CRC compared to individuals without.

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.

Hormone therapy in relation to survival from large bowel cancer

Epidemiologic studies of hormone therapy (HT) and colorectal cancer incidence consistently show an inverse association; however, few studies have considered prediagnostic use of HT on mortality among colorectal cancer patients. We evaluated the relationship of HT and survival among a population-based cohort of women with large bowel cancer. Cases (n=1,297) were newly diagnosed with invasive cancer of the colon or rectum, aged 40-74 years at diagnosis, who were identified by Wisconsin's statewide registry (1988-1991; 1997-2001) for two case-control studies. Information on HT use and other colorectal cancer risk factors was collected by standardized interview. There were 507 deaths (274 of these attributable to colorectal cancer) over 8.4 years of follow-up through December 2005. Hormone use was not associated with colorectal cancer mortality (adjusted hazard rate ratio=1.09, confidence interval=0.81-1.47). Colorectal cancer specific mortality was not associated with HT when considered separately by preparation type. Stage did not modify this relationship. Long-term HT was weakly positively associated with increased mortality after diagnosis of proximal colon, but not distal colon cancer. Because we detected no differences in survival among users of HT compared to non-users, the results suggest that HT use may affect only the incidence of some colorectal tumors.

Conjugated equine estrogens and colorectal cancer incidence and survival: the Women's Health Initiative randomized clinical trial

BACKGROUND

In separate Women's Health Initiative randomized trials, combined hormone therapy with estrogen plus progestin reduced colorectal cancer incidence but estrogen alone in women with hysterectomy did not. We now analyze features of the colorectal cancers that developed and examine the survival of women following colorectal cancer diagnosis in the latter trial.

PARTICIPANTS AND METHODS

10,739 postmenopausal women who were 50 to 79 years of age and had undergone hysterectomy were randomized to conjugated equine estrogens (0.625 mg/d) or matching placebo. Colorectal cancer incidence was a component of the monitoring global index of the study but was not a primary study endpoint. Colorectal cancers were verified by central medical record and pathology report review. Bowel exam frequency was not protocol defined, but information on their use was collected.

RESULTS

After a median 7.1 years, there were 58 invasive colorectal cancers in the hormone group and 53 in the placebo group [hazard ratio, 1.12; 95% confidence interval (95% CI), 0.77-1.63]. Tumor size, stage, and grade were comparable in the two randomization groups. Bowel exam frequency was also comparable in the two groups. The cumulative mortality following colorectal cancer diagnosis among women in the conjugated equine estrogen group was 34% compared with 30% in the placebo group (hazard ratio, 1.34; 95% CI, 0.58-3.19).

CONCLUSIONS

In contrast to the preponderance of observational studies, conjugated equine estrogens in a randomized clinical trial did not reduce colorectal cancer incidence nor improve survival after diagnosis.

Excess body weight and colorectal cancer risk in Canada: associations in subgroups of clinically defined familial risk of cancer

Overweight and obesity are linked with several chronic diseases, including colorectal cancer, among men, but results among women are equivocal. Previous evidence suggests that menopausal status, postmenopausal hormone use, and family history of cancer may modify the link between adiposity and colorectal cancer. In data from two population-based case-control studies (cases: 1,292 males and 1,404 females; controls: 1,465 males and 1,203 females) in Ontario and Newfoundland, Canada, we examined the link between colorectal cancer and body mass index (BMI) at two reference periods (BMI 2 years prior and BMI at age 20 years), weight gain since age 20 years, and height. Based on recent BMI indices among men, obesity (BMI >/=30 kg/m(2)) was associated with an 80% [95% confidence interval (95% CI), 1.43-2.27] increased risk of colorectal cancer relative to a normal BMI (18.5-24.9 kg/m(2)). The same comparison for BMI at age 20 years suggested a 94% increased risk of colorectal cancer (95% CI, 1.19-3.16). Odds ratios were similar among subgroups of men with and without a clinically defined familial risk of cancer (according to the Amsterdam or revised Bethesda criteria for Lynch syndrome). Associations were moderately stronger for cancer of the colon than cancer of the rectum. Among women, BMI and weight gain were not linked with colorectal cancer; the null associations were persistent in subgroups of familial risk of cancer, menopausal status, estrogenic status, and subsite. Tall height (>1.75 m), however, was linked with increased risk of colorectal cancer among women (odds ratio, 2.27; 95% CI, 1.46-3.59) but not among men. This study suggests that obesity is associated with increased risk of sporadic and Lynch syndrome-related colon and rectal cancers among men but not among women, whereas height is directly linked with all such cancers among women but not among men.