The effects of transdermal and oral oestrogen replacement therapy on colorectal cancer risk in postmenopausal women

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.

Aromatase inhibitors and the risk of colorectal cancer in postmenopausal women with breast cancer

Background

A large trial of postmenopausal women with breast cancer reported an imbalance in colorectal cancer events with aromatase inhibitors (AIs), compared with tamoxifen in the adjuvant setting. This unexpected signal was observed within 3 years of randomization. To date, no observational studies have examined this important safety question in the natural setting of clinical practice. Thus, the objective of this study was to determine whether AIs, when compared with tamoxifen, are associated with increased risk of colorectal cancer in postmenopausal women with breast cancer.

Patients and methods

Using the UK Clinical Practice Research Datalink, we identified women, at least 55 years of age, with breast cancer newly treated with either AIs or tamoxifen between 1 January 1996 and 30 September 2015, with follow-up until 30 September 2016. High-dimensional propensity score-adjusted Cox proportional hazards models were used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) of incident colorectal cancer associated with AIs when compared with tamoxifen overall, by cumulative duration of use, and time since initiation. All exposures were lagged by 1 year for latency considerations.

Results

A total of 9701 and 8893 patients initiated AIs and tamoxifen as first-line hormonal therapy (median follow-up of 2.4 and 2.9 years, respectively). Compared with tamoxifen, AIs were not associated with an increased risk of colorectal cancer (incidence rates of 150 per 100 000 person-years in both groups; adjusted HR: 0.90, 95% CI: 0.53-1.52). Similarly, there was no evidence of an association with cumulative duration of use (P-heterogeneity = 0.54), and time since initiation (P-heterogeneity = 0.66).

Conclusions

In this first population-based study, the use of AIs was not associated with an increased risk of colorectal cancer. These findings should provide reassurance to the concerned stakeholders.

The influence of hormone therapies on colon and rectal cancer

Exogenous sex hormones seem to play a role in colorectal carcinogenesis. Little is known about the influence of different types or durations of postmenopausal hormone therapy (HT) on colorectal cancer risk. A nationwide cohort of women 50-79 years old without previous cancer (n = 1,006,219) were followed 1995-2009. Information on HT exposures was from the National Prescription Register and updated daily, while information on colon (n = 8377) and rectal cancers (n = 4742) were from the National Cancer Registry. Potential confounders were obtained from other national registers. Poisson regression analyses with 5-year age bands included hormone exposures as time-dependent covariates. Use of estrogen-only therapy and combined therapy were associated with decreased risks of colon cancer (adjusted incidence rate ratio 0.77, 95 % confidence interval 0.68-0.86 and 0.88, 0.80-0.96) and rectal cancer (0.83, 0.72-0.96 and 0.89, 0.80-1.00), compared to never users. Transdermal estrogen-only therapy implied more protection than oral administration, while no significant influence was found of regimen, progestin type, nor of tibolone. The benefit of HT was stronger for long-term hormone users; and hormone users were at lower risk of advanced stage of colorectal cancer, which seems supportive for a causal association between hormone therapy and colorectal cancer.

Chemoprevention of colorectal cancer: a role for ursodeoxycholic acid, folate and hormone replacement treatment?

Chemoprevention of colorectal cancer has been an intense focus of research for many years. Among the possible candidate agents, ursodeoxycholic acid, folate, and hormone replacement therapy have been recently investigated with conflicting data. Experimental evidence shows that UDCA, folate and HRT target critical molecular events important for colon carcinogenesis. In animal models of sporadic, familial and inflammatory-associated cancers, they have shown to reduce colonic neoplasms. Observational studies have shown compelling evidence of possible protective effects of all three agents. However, randomised-controlled studies have yielded disappointing results, raising the issues of possible harm rather than protective effect for some of them. In this review experimental and clinical data on UDCA, folate and HRT as potential chemopreventive agents are discussed.

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.

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 potential for prevention of colorectal cancer in the UK

On the basis of recent trends (up to 2004), future projections of the incidence of colorectal cancer in the UK in the next 24 years are for a continuing decline in rates (age-standardized rates predicted to be about 9% lower). The potential for modification of the predicted burden through the implementation of five preventive interventions, for which national policies or targets have been promulgated, is examined. We estimate that 31.5% of cancers in men and 18.4% in women could be prevented if reasonable targets with respect to diet (reduced consumption of red meat, increased fruit and vegetables), exercise (30 min 5 days a week), alcohol consumption (3 U a day for men, 2 U for women) and weight control were achieved. This estimate assumes a return of the weight profile of the UK population to that present 20 years ago; if the aim were simply to halt the increasing trend in overweight, the preventable fractions would be 28% in men and 14.7% in women. These predictions suggest that realistic lifestyle modifications can result in a substantial reduction in cases of this major cancer. The benefit in terms of avoided deaths is probably greater than that which can be achieved through implementation of the national screening programme, and improvements in treatment.

Postmenopausal levels of endogenous sex hormones and risk of colorectal cancer

Observational epidemiologic studies and randomized trials have reported a protective effect of oral hormonal replacement therapy on risk of colorectal cancer. Only one previous prospective study, the Women's Health Initiative Observational Study, has reported on the relationship between endogenous hormones and incident colorectal cancer. Contrary to expectation, the investigators found that women with higher circulating estradiol levels were at increased risk of developing colorectal cancer. We conducted a case-control study nested within the New York University Women's Health Study prospective cohort to evaluate the association between endogenous levels of estrone, estradiol, and sex hormone-binding globulin (SHBG) with risk of colorectal cancer. We measured hormones and SHBG in serum samples collected at enrollment from a total of 148 women who subsequently developed colorectal cancer and 293 matched controls. Circulating estrone levels were positively associated with risk of colorectal cancer: The odds ratio for the highest versus lowest quartile of estrone was 1.8 (95% confidence interval, 1.0-3.3). We found a nonsignificant inverse association between SHBG and colorectal cancer, which disappeared after adjusting for body mass index. We did not find an association between estradiol and colorectal cancer risk, but we cannot rule out a potential association because of substantial laboratory error in the measurement. Our results suggest that endogenous estrone is associated with increased risk of colorectal cancer in postmenopausal women.

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.

Menopause hormone replacement therapy and cancer risk: an Italian record linkage investigation

BACKGROUND

The effects of persistence with hormone replacement therapy (HRT) on the risk of hospitalization for cancer and of the route of HRT administration on the risk of breast and colorectal cancer were explored in a large cohort study.

PATIENTS AND METHODS

The 73 505 women residing in Lombardia (Italy), aged 45-75 years, who received at least one HRT prescription during 1998-2000 were followed until 2005. Among these, 3687 experienced cancer hospitalization. Proportional hazards model was fitted to estimate the association between cumulative HRT persistence and cancer risk.

RESULTS

Compared with women who took HRT for <6 months, those exposed for >2 years showed hazard ratios (HR) of 0.78 (95% confidence interval 0.68-0.92) for colorectal cancer and 1.34 (1.13-1.58) for breast cancer. HR for breast cancer associated with long-term use of transdermal and oral HRT were, respectively, 1.27 (1.07-1.51) and 2.14 (1.43-3.21).

CONCLUSIONS

Evidence that long-term use of HRT is associated with increased risk of breast cancer and decreased risk of colorectal cancer is supplied from this study from a southern European population. Our findings indicate that transdermal therapy might have lower effect than oral therapy in increasing breast cancer risk.

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.

Two-stage case-control studies: precision of parameter estimates and considerations in selecting sample size

A two-stage case-control design, in which exposure and outcome are determined for a large sample but covariates are measured on only a subsample, may be much less expensive than a one-stage design of comparable power. However, the methods available to plan the sizes of the stage 1 and stage 2 samples, or to project the precision/power provided by a given configuration, are limited to the case of a binary exposure and a single binary confounder. The authors propose a rearrangement of the components in the variance of the estimator of the log-odds ratio. This formulation makes it possible to plan sample sizes/precision by including variance inflation factors to deal with several confounding factors. A practical variance bound is derived for two-stage case-control studies, where confounding variables are binary, while an empirical investigation is used to anticipate the additional sample size requirements when these variables are quantitative. Two methods are suggested for sample size planning based on a quantitative, rather than binary, exposure.

17β-Estradiol/levonorgestrel transdermal system for the management of the symptomatic menopausal woman

Recent publications of the initial outcomes from the Women's Health Initiative (WHI) study of menopausal management have raised concerns over the safety of hormone therapy [1,2]. Every study, no matter how large or well conducted, has biases and limitations that preclude the ability to apply the outcomes to a larger group of individuals not specifically evaluated in the analysis. In particular, the hormonal arms of the WHI evaluated only a single dose of a daily oral regimen of conjugated equine oestrogen 0.625 mg [1,2], combined with medroxyprogesterone acetate 2.5 mg if the subject had a uterus [1]. The failure to evaluate non-oral regimens prevented the evaluation of hormone delivery systems that have been shown to provide similar symptom relief to oral regimens, but with a considerably different physiological impact. The once-weekly transdermal patch (Climara Pro releasing 17beta-estradiol 0.045 mg/day and levonorgestrel 0.015 mg/day has been shown to be highly effective in rapidly reducing the frequency and intensity of vasomotor symptoms and to significantly improve all categories in the quality of life Women's Health Questionnaire [3]. In addition, this transdermal combination system was not associated with any cases of endometrial hyperplasia, adverse impacts on cholesterol or lipid values and was associated with an increasing rate of amenorrhoea over time [3]. The 17beta-estradiol/levonorgestrel transdermal system is approved in the US for the treatment of moderate-to-severe vasomotor symptoms and the prevention and treatment of urogenital atrophy.