Nested case-control study of the effects of non-steroidal anti-inflammatory drugs on breast cancer risk and stage

Association between NSAIDs use and breast cancer risk: a systematic review and meta-analysis

The association between non-steroidal anti-inflammatory drugs (NSAIDs) use and breast cancer has remained controversial. Therefore, an overall quantitative estimate of the association needs to be studied. A systematic review and meta-analysis was executed to explore the pooled estimate for relative risk (RR) and 95% confidence interval (CI) using random or fixed effects models based on heterogeneity analysis. Overall 26 studies with 528,705 participants were included. The RR of NSAIDs use and the incidence of breast cancer was 0.94 (95% CI: 0.88-1.00) with random effects model. A slight reduction of breast cancer by taking aspirin and ibuprofen was both observed with pooled RR of 0.91 (95% CI: 0.83-0.98) and 0.81 (95% CI: 0.67-0.97), respectively. Our results indicate that NSAIDs use is associated with a slight decrease for the development of breast cancer with a marginally statistical significant difference. The associations are slightly more obvious in aspirin and ibuprofen use.

Breast cancer and use of nonsteroidal anti-inflammatory drugs: a meta-analysis

BACKGROUND

Breast cancer is one of the leading causes of mortality among women. The use of nonsteroidal anti-inflammatory drugs (NSAIDs) may be associated with reduced risk for breast cancer, but results from these studies of the association have been inconsistent.

METHODS

Studies that examined the association between risk of breast cancer and use of NSAIDs, including aspirin and ibuprofen, that were published between January 1, 1966, and July 1, 2008, were identified using Medline, EMBASE, and other databases. We performed meta-analysis by pooling studies according to the inverse of their variances and performed separate analyses of studies pooled according to aspirin use and ibuprofen use. We evaluated publication bias and study quality.

RESULTS

A total of 38 studies (16 case-control studies, 18 cohort studies, 3 case-control studies nested in well-defined cohorts, and 1 clinical trial) that included 2 788 715 subjects were identified. The results of these studies suggest that overall, NSAID use was associated with reduced risk for breast cancer (relative risk [RR] = 0.88, 95% confidence interval [CI] = 0.84 to 0.93). Specific analyses for aspirin (RR = 0.87, 95% CI = 0.82 to 0.92) and ibuprofen (RR = 0.79, 95% CI = 0.64 to 0.97) yielded similar results.

CONCLUSIONS

This meta-analysis provides evidence that NSAID use is associated with reduced risk for breast cancer. Future research should include careful evaluation of the biologic mechanisms involved in the relationship between NSAIDs and breast cancer.

Nonsteroidal anti-inflammatory drugs and change in mammographic density: a cohort study using pharmacy records on over 29,000 postmenopausal women

BACKGROUND

Use of nonsteroidal anti-inflammatory drugs (NSAID) has been associated with a decrease in breast cancer risk, but it is unknown if they also reduce mammographic density, a strong intermediate marker of breast cancer risk.

METHODS

We investigated NSAID use and mammographic density in 29,284 postmenopausal women who had two screening mammograms at Group Health in Seattle. We used pharmacy records to classify women as NSAID nonusers, continuers, initiators, or discontinuers based on use between the two mammograms and nine separate prescription and nonprescription NSAID classes. Using unordered polytomous logistic regression methods, we modeled the odds ratio (OR) of staying not dense, decreasing density, or increasing density relative to remaining dense based on Breast Imaging Reporting Data System classification of density.

RESULTS

There was no association with density change from initiation or continuation of NSAIDs. However, both initiators and continuers of any NSAIDs were more likely to stay not dense than stay dense [OR, 1.12; 95% confidence interval (95% CI), 1.04-1.20; OR, 1.25; 95% CI, 1.05-1.49, respectively]. This association with staying not dense for initiators and continuers of any NSAID use was observed primarily among women ages <65 years at first mammogram (OR, 1.24; 95% CI, 1.12-1.36; OR, 1.48; 95% CI, 1.14-1.93, respectively).

CONCLUSIONS

Initiation of NSAID use did not reduce mammographic density over the short term. Continuers of NSAID use were more likely to stay not dense compared with nonusers, suggesting that it is plausible that longer-term use of NSAIDs may be needed to reduce density.

Nonsteroidal anti-inflammatory drug use and breast cancer risk: a Danish cohort study

Epidemiologic studies investigating the effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on breast cancer have yielded conflicting results. We examined the association between use of aspirin and nonaspirin NSAIDs and breast cancer risk among 28 695 women in the Danish Diet, Cancer and Health cohort. Information on NSAID and paracetamol use was obtained from a self-administered questionnaire completed at baseline (1993-1997) and updated through 2003 using a nationwide prescription database. Detailed information on breast cancer incidence and tumour characteristics was obtained from nationwide health registers. Cox proportional hazards regression was used to compute incidence rate ratios (RRs) and 95% confidence intervals (CIs). We identified 847 breast cancer cases over an average follow-up period of 7.5 years. Any NSAID use at baseline was associated with an increased incidence of breast cancer compared with nonuse (RR, 1.27; 95% CI, 1.10-1.45). A similar result was observed for any NSAID use in a combined analysis of baseline and prescription data (1.34; 95% CI, 1.15-1.56). Aspirin-only users experienced a slightly higher breast cancer incidence (RR, 1.38; 95% CI, 1.12-1.69) than exclusive users of nonaspirin NSAIDs (RR, 1.25; 95% CI, 1.04-1.49). Introduction of a lag time of 1 year provided similar results. We found no clear differences in risk estimates with frequency, recency or duration of NSAID use, or by hormone receptor status of the breast tumours. Paracetamol use was unrelated to breast cancer incidence. The increased breast cancer incidence among NSAID users may reflect a noncausal association, but our study provides no evidence of a chemopreventive effect of NSAIDs against breast cancer over the durations studied.

Nonsteroidal anti-inflammatory drug use and serum total estradiol in postmenopausal women

Laboratory and epidemiologic evidence suggest that nonsteroidal anti-inflammatory drug (NSAID) use may be inversely related to the risk of breast cancer; however, the mechanism by which NSAIDs may protect against the development of this disease is uncertain. The objective of this observational study was to assess the relationship between current NSAID use and endogenous estradiol levels, an established breast cancer risk factor. To evaluate this aim, we conducted a cross-sectional investigation among 260 postmenopausal women who were not recently exposed to exogenous hormones. Information on current NSAID use (aspirin, cyclooxygenase-2 inhibitors, and other NSAIDs combined) was collected using a questionnaire at the time of blood draw. Estradiol was quantified in serum by radioimmunoassay. General linear models were used to evaluate the association between NSAID use and serum total estradiol. The age-adjusted and body mass index-adjusted geometric mean serum estradiol concentration among NSAID users (n = 124) was significantly lower than nonusers of NSAIDs (n = 136; 17.8 versus 21.3 pmol/L; P = 0.03). Further adjustment for additional potential confounding factors did not substantially alter estimates (17.7 versus 21.2 pmol/L; P = 0.03). To our knowledge, this report is the first to examine the relationship between NSAID use and serum estradiol in postmenopausal women. These cross-sectional findings suggest that NSAID use may be associated with lower circulating estradiol levels, potentially representing one mechanism through which NSAIDs exert protective effects on breast cancer.

Nonsteroidal anti-inflammatory drugs and breast cancer risk in the National Institutes of Health-AARP Diet and Health Study

Introduction

By inhibiting cyclooxygenase-2, nonsteroidal anti-inflammatory drugs (NSAIDs) decrease aromatase activity and might reduce breast cancer risk by suppressing estrogen synthesis. Epidemiologic evidence for a protective role of NSAIDs in breast cancer, however, is equivocal.

Methods

We tested NSAID use for its association with breast cancer incidence in the National Institutes of Health–AARP Diet and Health Study, where 127,383 female AARP (formerly known as the American Association of Retired Persons) members with no history of cancer, aged 51 to 72 years, completed a mailed questionnaire (1996 to 1997). We estimated relative risks of breast cancer for NSAID exposures using multivariate Cox proportional hazards regression models. The state cancer registry and mortality index linkage identified 4,501 primary incident breast cancers through 31 December 2003, including 1,439 estrogen receptor (ER)-positive cancers and 280 ER-negative cancers.

Results

Proportional hazards models revealed no statistically significant association between overall NSAIDs and total breast cancer. As cyclooxygenase inhibition by aspirin (but not other NSAIDs) is irreversible, we tested associations by NSAID type. Although we observed no significant differences in risk for daily use (versus nonuse) of aspirin (relative risk = 0.93, 95% confidence interval = 0.85 to 1.01) or nonaspirin NSAIDS (relative risk = 0.96, 95% confidence interval = 0.87 to 1.05), risk of ER-positive breast cancer was significantly reduced with daily aspirin use (relative risk = 0.84, 95% confidence interval = 0.71 to 0.98) – a relationship not observed for nonaspirin NSAIDS. Neither aspirin nor nonaspirin NSAIDs were associated with risk of ER-negative breast cancer.

Conclusion

Breast cancer risk was not significantly associated with NSAID use, but daily aspirin use was associated with a modest reduction in ER-positive breast cancer. Our results provide support for further evaluating relationships by NSAID type and breast cancer subtype.

Risk of breast cancer in relation to antibiotic use

BACKGROUND

There are conflicting results in the literature regarding the association between the antibiotic exposure and breast cancer risk. The aim of this study was to assess this association using a population-based approach.

METHODS

The source population was the dynamic cohort defined by membership in the Saskatchewan Prescription Drug Plan (Canada) between the years 1981 and 2000. Four matched controls were selected for each case identified by the Saskatchewan Cancer Agency, using incidence density sampling. Detailed drug exposure over a minimum of 15 years before diagnosis allowed studying the respective effects of dosage and timing of antibiotic use on breast cancer risk. Two antibiotic exposure definitions were used: the number of prescriptions and the number of units (tablets, capsules, etc.), which were further categorized into quartiles.

RESULTS

A total of 3099 breast cancer cases and 12,396 matched controls were included. The incidence of breast cancer was higher in subjects who had more antibiotic prescriptions during the 1-15 years prior to the index date (RRs = 1.50, 1.63, 1.71 and 1.79 for the four quartiles, respectively, p-trend = 0.0001). Similar results were found when a number of units were considered. We did not find any effect of the timing of antibiotic exposure on breast cancer risk. Similar patterns of increased risk of breast cancer were detected for the specific antibiotic classes.

CONCLUSIONS

We observed a dose-dependent increase in breast cancer risk in association with the antibiotic exposure up to 15 years in the past. However, the lack of temporal trends and the absence of class-specific effects suggest a non-causal relationship.

Inflammation and breast cancer. Cyclooxygenase/prostaglandin signaling and breast cancer

Many human cancers exhibit elevated prostaglandin (PG) levels due to upregulation of cyclooxygenase-2 (COX-2), a key enzyme in eicosanoid biosynthesis. COX-2 over-expression has been observed in about 40% of cases of invasive breast carcinoma and at a higher frequency in preinvasive ductal carcinoma in situ tumors, Extensive pharmacologic and genetic evidence implicates COX enzymes in neoplasia. Epidemiologic analyses demonstrate a protective effect of COX-inhibiting nonsteroidal anti-inflammatory drugs with respect to human cancer. Complementary experimental studies have established that both conventional nonsteroidal anti-inflammatory drugs and selective COX-2 inhibitors suppress mammary tumor formation in rodent breast cancer models. Furthermore, knocking out Cox-2 reduces mammary tumorigenesis and angiogenesis, and, conversely, transgenic COX-2 over-expression induces tumor formation. The utility of COX/PG signaling as a target for chemoprevention has been established by randomized controlled clinical trials. However, these studies also identified increased cardiovascular risk associated with use of selective COX-2 inhibitors. Thus, current efforts are directed toward identifying safer approaches to antagonizing COX/PG signaling for cancer prevention and treatment, with a particular focus on PGE₂ regulation and signaling, because PGE₂ is a key protumorigenic prostanoid.

NSAIDs and breast cancer: a possible prevention and treatment strategy

CONTEXT

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX) and thereby reduce prostaglandin synthesis. Abnormally upregulated COX and prostaglandins are features of breast cancer so NSAIDs might have a role in treatment and prevention of the disease.

OBJECTIVE

To review the available epidemiological data on the relation between NSAIDs and risk of breast cancer together with interventional studies in established disease.

RESULTS

Both case-control and cohort studies indicate a moderate reduction in risk of breast cancer among women taking NSAID particularly aspirin. There may be a reduction in oestrogen receptor positive tumours in aspirin users but results are heterogeneous. It is not possible to estimate the dose-response effect for duration of use. In patients with breast cancer, aspirin increased levels of serum nitric oxide (NO) and maspin both of which inhibit growth of breast cancer cells in vitro. Furthermore, a reduced breast cancer and all-cause mortality has been reported in those taking NSAIDs after diagnosis. The cyclooxygenase 2 (COX-2) inhibitor celecoxib showed promising preliminary efficacy and acceptability in combination with exemestane in advanced breast cancer although cardiotoxicity led to discontinuation of celecoxib in a prevention trial for individuals with colonic polyps.

CONCLUSIONS

NSAIDs may reduce breast cancer risk by 20% but the optimal type, dose and duration is still undetermined together with the feasibility of such an intervention in an at risk population. There may be a role for NSAIDs in combination with endocrine therapies as either an adjuvant or palliative treatment for women with established breast cancer.

Adjustments for unmeasured confounders in pharmacoepidemiologic database studies using external information

BACKGROUND

Nonexperimental studies of drug effects in large automated databases can provide timely assessment of real-life drug use, but are prone to confounding by variables that are not contained in these databases and thus cannot be controlled.

OBJECTIVES

To describe how information on additional confounders from validation studies can help address the problem of unmeasured confounding in the main study.

RESEARCH DESIGN

Review types of validation studies that allow adjustment for unmeasured confounding and illustrate these with an example.

SUBJECTS

Main study: New Jersey residents age 65 years or older hospitalized between 1995 and 1997, who filled prescriptions within Medicaid or a pharmaceutical assistance program. Validation study: representative sample of Medicare beneficiaries.

MEASURES

Association between nonsteroidal antiinflammatory drugs (NSAIDs) and mortality.

RESULTS

Validation studies are categorized as internal (ie, additional information is collected on participants of the main study) or external. Availability of information on disease outcome will affect choice of analytic strategies. Using an external validation study without data on disease outcome to adjust for unmeasured confounding, propensity score calibration (PSC) leads to a plausible estimate of the association between NSAIDs and mortality in the elderly, if the biases caused by measured and unmeasured confounders go in the same direction.

CONCLUSIONS

Estimates of drug effects can be adjusted for confounders that are not available in the main, but can be measured in a validation study. PSC uses validation data without information on disease outcome under a strong assumption. The collection and integration of validation data in pharmacoepidemiology should be encouraged.

Cyclooxygenase-2 mRNA expression correlates with aromatase expression in human breast cancer

INTRODUCTION

The cyclooxygenase-2 (COX-2), responsible for the conversion of arachidonic acid into prostaglandin (PG) E2, is known to increase intracellular cAMP and estrogen production in malignant breast tissue. The aromatase enzyme complex is responsible for local production of estrogens in breast cancer. Increasing evidence supports a role for COX-2 in upregulation of aromatase activity. The aim of this study was to examine the relationship between COX-2 and aromatase mRNA expression in human breast cancer.

METHODS

A total of 160 breast samples (127 tumor tissues and 33 normal tissues) were analyzed. Levels of transcription were determined using real-time quantitative PCR. COX-2 and aromatase mRNA expression were normalized against CK19. Levels of expression of COX-2 were correlated with those of aromatase using Pearson's correlation method.

RESULTS

Levels of expression of COX-2/CK19 of both benign and malignant tissues were positively correlated with aromatase/CK19 transcript levels (correlation coefficient = +0.536, P < 0.0001). When we compared levels of expression of both genes in malignant samples only, there was a highly significant positive correlation (r = +0.611, P < 0.00001).

CONCLUSION

This study demonstrates a strong positive relationship between COX-2 and aromatase mRNA expression, and lends further support to the hypothesis that COX-2 is an upregulator of aromatase in breast tissue.

Trastuzumab not for ductal carcinoma in situ?

Ductal carcinoma in situ (DCIS) is a preinvasive breast lesion accounting for approximately 30% of all newly detected breast cancers in the US. DCIS has been separated into two groups by architecture (comedo versus noncomedo) and nuclear grade. The expression of biological markers in DCIS, however, would reflect the true biologic potential of the lesion. Patients with estrogen receptor (ER)-negative, human epidermal growth factor-2 (HER-2)-positive DCIS pose a treatment challenge. They are not candidates for tamoxifen; trastuzumab has an undetermined role in DCIS. In this report, we present a case of a 45-year-old woman diagnosed with invasive breast cancer and ER-negative/HER-2-positive DCIS who developed recurrence and progression of DCIS as manifested by a new palpable mass while receiving trastuzumab as part of adjuvant treatment for invasive breast cancer. The potential clinical implications are discussed.

Cyclooxygenase-2 (cox-2) and the inflammogenesis of cancer

Cohesive scientific evidence from molecular, animal, and human investigations supports the hypothesis that aberrant induction of COX-2 and up-regulation of the prostaglandin cascade play a significant role in carcinogenesis, and reciprocally, blockade of the process has strong potential for cancer prevention and therapy. Supporting evidence includes the following: [1] expression of constitutive COX-2-catalyzed prostaglandin biosynthesis is induced by most cancer-causing agents including tobacco smoke and its components (polycylic aromatic amines, heterocyclic amines, nitrosamines), essential polyunsaturated fatty acids (unconjugated linoleic acid), mitogens, growth factors, proinflammatory cytokines, microbial agents, tumor promoters, and other epigenetic factors, [2] COX-2 expression is a characteristic feature of all premalignant neoplasms, [3] COX-2 expression is a characteristic feature of all malignant neoplasms, and expression intensifies with stage at detection and cancer progression and metastasis, [4] all essential features of carcinogenesis (mutagenesis, mitogenesis, angiogenesis, reduced apoptosis, metastasis, and immunosuppression) are linked to COX-2-driven prostaglandin (PGE-2) biosynthesis, [5] animal studies show that COX-2 up-regulation (in the absence of genetic mutations) is sufficient to stimulate the transformation of normal cells to invasive cancer and metastatic disease, [6] non-selective COX-2 inhibitors, such as aspirin and ibuprofen, reduce the risk of human cancer and precancerous lesions, and [7] selective COX-2 inhibitors, such as celecoxib, reduce the risk of human cancer and precancerous lesions at all anatomic sites thus far investigated. Results confirming that COX-2 blockade is effective for both cancer prevention and therapy have been tempered by observations that some COX2 inhibitors pose a risk to the cardiovascular system, and more studies are needed in order to determine if certain of these drugs can be taken at dosages that prevent cancer without increasing cardiovascular risk. It is emphasized that the "inflammogenesis model of cancer" is not mutually exclusive and may in fact be synergistic with the accumulation of somatic mutations in tumor suppressor genes and oncogenes or epigenetic factors in the development of cancer.

The role of cyclooxygenase-2 in breast cancer: review

There is a growing body of evidence that COX-2 expression s a fundamental step in breast cancer pathogenesis acting through prostaglandin-dependent and independent mechanisms. Epidemiological studies suggest that NSAIDs confer a moderate degree of benefit against breast cancer. However further work is required to establish how this enzyme system can be best manipulated for therapeutic benefit.

COX-2 expression in lobular in situ neoplasia of the breast: correlation with histopathological grading system according to the Tavassoli classification

AIMS

There is considerable evidence to link cyclooxygenase (COX)-2 to the development of cancer. The aim of this study was to assess COX-2 expression and its subcellular localization in lobular in situ neoplasia (LIN) of the breast and to verify differences in COX-2 expression between different grades of lesions according to the Tavassoli classification.

METHODS AND RESULTS

We analysed the expression of COX-2 protein by immunohistochemistry in tissue samples of 51 LIN lesions classified into three grades according to the Tavassoli classification. COX-2 immunostaining was observed in 78.4% of LIN samples and showed a prevalent membranous rather than cytoplasmic pattern. COX-2 was expressed in 16/17 (94.1%) LIN1, 22/25 (88%) LIN2 and 2/9 (22.2%) LIN3. As regards COX-2 expression, a statistically significant difference was found between LIN1 and LIN3 (P = 0.001) and between LIN2 and LIN3 (P =0.001). No difference was found between LIN1 and LIN2. Moreover, a significant negative correlation was found between LIN grade and COX-2 expression (P < 0.0001).

CONCLUSIONS

COX-2 is highly expressed in LIN, supporting a role for this protein in the early stage of breast carcinogenesis, representing the rationale for using COX-2 selective inhibitors in the earliest stages of breast cancer.

Functional polymorphisms in the cyclooxygenase 2 (COX-2) gene and risk of breast cancer in a Chinese population

Cyclooxygenase (COX), the rate-limiting enzyme in prostaglandins (PG) synthesis, exists in at least two isoforms, COX-1 and COX-2. COX-2 plays an important role in carcinogenesis, and overexpression may increase proliferation, inhibit apoptosis, and enhance the invasiveness of breast cancer cells. Polymorphisms in the regulatory regions of the COX-2 gene may influence function and/or expression and contribute to interindividual variability in susceptibility to cancer. In this study three variants (-1195G/A and -765G/C in the promoter and 8473C/T in 3'UTR) of COX-2 were examined for correlation with breast cancer risk. A case-control study of 615 histologically confirmed breast cancer patients and 643 cancer-free controls frequency-matched for age were selected. Logistic regression analyses revealed that no overall significant associations were detected in the single-locus analysis between three polymorphisms of COX-2 and the risk of breast cancer. However, a significantly increased risk of breast cancer was associated with the combined genotypes containing "more than 3 variant alleles"' (adjusted OR = 1.37, 95% CI 1.01-1.84) compared with the combined genotypes with "0-3 variant alleles." Haplotype analyses showed that haplotypes A-1195G-765T8473 and A-1195C-765T8473 were significantly associated with breast cancer risk (OR = 1.20, 95% CI 1.01-1.43 for A-1195G-765T8473; OR = 9.16, 95% CI 1.14-73.51 for A-1195C-765T8473) compared with the most common haplotype, G-1195G-765T8473. These findings indicate that these three variants in the regulatory regions of COX-2 may contribute to the etiology of breast cancer.

The status of cyclooxygenase-2 expression in ductal carcinoma in situ lesions and invasive breast cancer correlates to cyclooxygenase-2 expression in normal breast tissue

OBJECTIVES

There is a paucity of data on cyclooxygenase (COX)-2 expression in normal breast tissue and on the changes in COX-2 expression from normal tissue via ductal carcinoma in situ (DCIS) lesions to invasive cancer. The aim of this study, therefore, was to investigate COX-2 protein expression in normal breast tissue, DCIS, and invasive breast cancer in samples from the same patients.

METHODS

In 39 patients, we investigated and compared COX-2 expression in paired samples of invasive cancer and normal adjacent breast epithelium by immunohistochemistry with a monoclonal COX-2 antibody. Furthermore, in 29 of these cases, we also analyzed a concomitant DCIS lesion.

RESULTS

Patients without COX-2 expression in normal breast tissue also do not express COX-2 in invasive breast cancer and in DCIS lesions, respectively. Conversely, COX-2 expression in normal breast tissue was an indicator for COX-2 expression in the paired breast tumors. There was no significant correlation between COX-2 expression and pathologic tumor stage, nodal status, hormone receptor status, tumor size, grading, and lymphovascular space involvement.

CONCLUSIONS

This is the largest study to date investigating COX-2 in paired samples of breast tumors and normal adjacent breast tissue. Our data are consistent with the hypothesis that COX-2 overexpression is an early event in breast carcinogenesis.

Nonsteroidal anti-inflammatory drugs and the risk of developing breast cancer in a population-based prospective cohort study in Washington County, MD

The objective of this study was to examine the association between nonsteroidal anti-inflammatory drug (NSAID) use and the development of breast cancer, and to assess whether this association differed by estrogen receptor (ER) subtype. Data were analyzed from 15,651 women participating in CLUE II, a cohort study initiated in 1989 in Washington County, MD. Medication data were collected at baseline in 1989 and in 1996. Incident cases of invasive breast cancer occurring from baseline to March 27, 2006 were identified through linkage of cohort participants with the Washington County Cancer Registry and the Maryland State Cancer Registry. Cox proportional hazards modeling was used to calculate the risk ratios (RR) and 95% confidence intervals (95% CI) for breast cancer associated with medication use. Among women in the CLUE II cohort, 418 invasive breast cancer cases were identified during the follow-up period. The results showed that self-reported use of NSAIDs in both 1989 and in 1996 was associated with a 50% reduction in the risk of developing invasive breast cancer compared with no NSAID use in either 1989 or 1996 (RR = 0.50; 95% CI 0.28, 0.91). The protective association between NSAID use and the risk of developing breast cancer was consistent among ER-positive and ER-negative breast cancers, although only the RR for ER-positive breast cancer was statistically significant. Overall, findings from this study indicate that NSAID use is associated with a decrease in breast cancer risk and that the reduction in risk is similar for ER-positive and ER-negative tumors.

Progress in chemoprevention drug development: the promise of molecular biomarkers for prevention of intraepithelial neoplasia and cancer--a plan to move forward

This article reviews progress in chemopreventive drug development, especially data and concepts that are new since the 2002 AACR report on treatment and prevention of intraepithelial neoplasia. Molecular biomarker expressions involved in mechanisms of carcinogenesis and genetic progression models of intraepithelial neoplasia are discussed and analyzed for how they can inform mechanism-based, molecularly targeted drug development as well as risk stratification, cohort selection, and end-point selection for clinical trials. We outline the concept of augmenting the risk, mechanistic, and disease data from histopathologic intraepithelial neoplasia assessments with molecular biomarker data. Updates of work in 10 clinical target organ sites include new data on molecular progression, significant completed trials, new agents of interest, and promising directions for future clinical studies. This overview concludes with strategies for accelerating chemopreventive drug development, such as integrating the best science into chemopreventive strategies and regulatory policy, providing incentives for industry to accelerate preventive drugs, fostering multisector cooperation in sharing clinical samples and data, and creating public-private partnerships to foster new regulatory policies and public education.

Use of nonsteroidal antiinflammatory drugs and non-Hodgkin lymphoma: a population-based case-control study

The association between long-term use of nonsteroidal antiinflammatory drugs (NSAIDs) and non-Hodgkin lymphoma (NHL) was examined using data collected between October 2001 and May 2004 in an ongoing population-based case-control study in the San Francisco Bay Area. NHL cases were identified using rapid case ascertainment and Surveillance, Epidemiology, and End Results registry data. Control participants were frequency-matched to cases by age, sex, and county of residence. Participants completed in-person interviews designed to measure potential NHL risk factors. Questions were asked regarding use during the past 20 years of aspirin, prescription and over-the-counter nonselective NSAIDs, and cyclooxygenase-2 (COX-2) inhibitors. A total of 1,000 cases and 1,060 controls contributed data for these interim analyses. Analyses were carried out for men and women and for both sexes combined. After adjustment for age and sex, there was no consistent association between long-term use and NHL for all NSAIDs combined, aspirin, nonselective NSAIDs, and COX-2 inhibitors. For women, long-term aspirin use may be associated with a decreased risk of NHL (for 3-<9 years of use, odds ratio=0.41, 95% confidence interval: 0.18, 0.94). Conversely, although the confidence intervals were wide, the adjusted odds ratios for COX-2 inhibitor use were nearly twofold for women, indicating a possible increase in NHL risk associated with regular use of COX-2 inhibitors.

NSAID use and survival after breast cancer diagnosis in post-menopausal women

Many epidemiologic studies, although not all, have shown an inverse relation between non-steroidal anti-inflammatory drug (NSAID) use and risk of incident breast cancer, but the possible influence of NSAID use on breast cancer survival has not been evaluated. We examined the association between self-reported NSAID use and survival after invasive breast cancer diagnosis among 591 postmenopausal women in a prospective study. Cox proportional hazards regression was used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for breast cancer death as well as all-cause mortality associated with NSAID use. There was an indication of reduced risk of breast cancer mortality and all-cause mortality for women reporting any versus no use of NSAIDs, with multivariate-adjusted HRs of 0.64 (95% CI 0.39-1.05) and 0.57 (95% CI 0.40-0.81), respectively. There was no trend of decreasing risk of death with increasing frequency of NSAID use per week. While the results from this exploratory analysis are preliminary, there is biological plausibility for such an association. Further studies should consider whether NSAIDs, which have biological activity affecting tumor promotion and progression and appear to protect against breast cancer incidence, may be associated with better prognosis after a diagnosis of invasive breast cancer.

Cyclooxygenase-2 as a target for anticancer drug development

The two isoforms cyclooxygenase-1 and -2 catalyze the initial step in the formation of prostaglandins in a variety of pathophysiological processes. More recently their role in carcinogenesis has become more evident. They seem to influence apoptosis, angiogenesis, and invasion, and play a role in the production of carcinogens. Usually, a high level of COX-2 expression is found in cancer cells. However, low COX-2 expression is observed in some cancers like prostate or breast cancer. This phenomenon is quite surprising and should influence on clinical trial designs. Large epidemiological trials studying users and non-users of aspirin have shown that cyclooxygenase (COX) inhibitors and non-steroidal anti-inflammatory drugs (NSAIDs) could be of benefit against the development and growth of malignancies. Moreover, clinical trials in patients with familial adenomatosis polyposis syndrome have shown too the efficacy of non-selective COX inhibitors and recently also of selective COX-2 inhibitors in the reduction of the number and the size of colorectal polyps. However, a primary chemopreventive effect has not been demonstrated yet. NSAIDs are also supposed to have a preventive and growth inhibitory effect in extra-colonic epithelial malignancies. Several preclinical studies show promising results with combination treatments of either chemotherapy or radiotherapy with COX inhibitors. Preclinical studies with the simultaneous use of inhibitors of the epidermal growth factor receptor and COX-2 inhibitors have shown also promising results. Encouraging results with the first clinical trials combining chemotherapy with COX-2 inhibitors in patients with cancer in the advanced and neoadjuvant setting have recently been reported. However, NSAIDs effects in cancer cells are mediated not only by COX enzymes but also by interactions with downstream effectors of COX-2. Hence, we can state that targeting the COX-2 pathway is a promising strategy in the prevention and treatment of solid tumors. Ongoing trials are expected to answer - at least partly - the remaining questions concerning COX-2 and cancer.

Expression of cyclooxygenase-2 in breast carcinogenesis and its relation to HER-2/neu and p53 protein expression in invasive ductal carcinoma

The purpose of this study was to evaluate cyclooxygenase-2 (COX-2) expression in the successive steps of breast carcinogenesis and to determine its correlation with HER-2/neu and p53 expression in invasive ductal carcinomas of the breast. Immunohistochemical staining with anti-COX-2 antibody was performed in normal breast tissue, usual hyperplasia, ductal carcinoma in situ, and invasive ductal carcinoma. Expression of COX-2 in invasive ductal carcinoma was correlated with immunohistochemical expression of HER-2/neu and p53 protein. COX-2 expression was found to be progressively elevated along the continuum from normal breast tissue to invasive ductal carcinoma (P<0.001). COX-2 expression significantly correlated with p53 and HER-2/neu protein expression (P<0.05 and P<0.001). On multivariate analysis, only TNM stage and elevated COX-2 expression correlated with survival. Our results suggest that COX-2 may be involved in the carcinogenesis of the breast and may be an independent prognostic indicator in patients with invasive ductal carcinoma. HER-2/neu and p53 are likely to be involved in the regulation of COX-2 expression in invasive ductal carcinomas of the breast.

Cyclo-oxygenase-2 (COX-2) mRNA expression and hormone receptor status in breast cancer

AIMS

The purpose of this study was to evaluate COX-2 mRNA expression with known clinical prognostic features of breast cancer, oestrogen/progesterone receptor status, tumour size and grade.

METHODS

Total RNA was extracted from 45 frozen breast tumour (invasive) and 22 normal breast tissue samples. COX-2 mRNA transcription was quantified using a real time RT-PCR assay and expressed as copy number/microg total RNA. All specimens were assessed for tumour grade, size, nodal status and presence of vascular invasion and oestrogen and progesterone receptor status.

RESULTS

COX-2 mRNA was detected in all samples with a median copy number of 1.15 x 10(7) for tumours and 6.5 x 10(6) for normal samples. Expression was significantly higher in oestrogen receptor negative tumours compared to the receptor positive group. There was no correlation between COX-2 mRNA levels and tumour size, grade, nodal status and presence of vascular invasion.

CONCLUSIONS

COX-2 mRNA expression is increased in oestrogen and progesterone receptor negative breast cancers.

Nonsteroidal antiinflammatory drugs, cyclooxygenase polymorphisms, and the risk of developing breast carcinoma among women with benign breast disease

BACKGROUND

Biopsy-proven benign breast disease (BBD) is a risk factor for developing breast carcinoma; however, to the authors' knowledge, little is known regarding factors related to progression to carcinoma. A cohort study was conducted to examine the role of cyclooxygenase (COX) polymorphisms and nonsteroidal anti-inflammatory drugs (NSAIDs) in the progression of BBD to breast carcinoma.

METHODS

Among participants in an ongoing cohort study, 1467 women underwent a breast biopsy for BBD. Of these women, 91 subsequently developed breast carcinoma. Medication data were collected in 1989 and in 1996. COX genotypes were determined using DNA extracted from blood specimens collected in 1989.

RESULTS

A decrease in breast carcinoma risk was observed among women who reported using aspirin in 1989 (odds ratio [OR] of .46; 95% confidence interval [95% CI], .22-.98) and in 1996 (OR of .47, 95% CI, .18-1.21). Furthermore, a higher frequency, dose, and longer duration of aspirin use were associated with a decrease in the odds of developing breast carcinoma. Overall, no association was observed between COX genotypes and the subsequent development of breast carcinoma. However, among women not using NSAIDs, one COX-2 polymorphism (rs2143416) was found to be significantly associated with the development of breast carcinoma.

CONCLUSIONS

Findings from the current study suggest that inflammation through COX-2 pathways may play a role in the progression of BBD to breast carcinoma and that aspirin may help to lower the risk of progression to breast carcinoma among women with BBD.

Endometriosis as a model for inflammation–hormone interactions in ovarian and breast cancers

Chronic inflammation has been implicated in a variety of cancers. In this review, we consider associations between endometriosis and cancers both local (ovarian) and distant (breast). We review the epidemiological data linking endometriosis to ovarian and breast cancers. We then consider evidence for a role for sex steroid hormones and for inflammation in the aetiology of each of these cancers. Finally, we consider that endometriosis may promote alterations in sex steroid hormones and inflammatory mediators. A possible explanation for the association between endometriosis and these reproductive cancers may then be local and systemic enhancement of aberrant inflammatory and hormonal mediators. If this hypothesis is true, endometriosis may need to be considered as a risk factor for ovarian and breast cancers, triggering increasingly intensive surveillance. Moreover, treatments for endometriosis may require consideration of the impact on long-term cancer risk.

COX inhibitors and breast cancer

There is considerable evidence to suggest that prostaglandins play an important role in the development and growth of cancer. The enzyme cyclo-oxygenase (COX) catalyses the conversion of arachidonic acid to prostaglandins. In recent years, there has been interest in a possible role for COX inhibitors in the prevention and treatment of malignancy. Cyclo-oxygenase-2 (COX-2) is overexpressed in several epithelial tumours, including breast cancer. Preclinical evidence favours an antitumour role for COX inhibitors in breast cancer. However, the epidemiological evidence for an association is conflicting. Trials are being conducted to study the use of COX inhibitors alone and in combination with other agents in the chemoprevention of breast cancer, and in the neo-adjuvant, adjuvant, and metastatic treatment settings. In evaluating the potential use of these agents particularly in cancer chemoprophylaxis, the safety profile is as important as their efficacy. Concern over the cardiovascular safety of both selective and nonselective COX-inhibitors has recently been highlighted.

Serum lipid profiles in patients receiving endocrine treatment for breast cancer--the results from the Celecoxib Anti-Aromatase Neoadjuvant (CAAN) Trial

BACKGROUND

Anti-aromatase therapy is important in the treatment of breast cancer. Cyclooxygenase-2 (COX-2) inhibitors may be effective in chemoprevention. A proof of principle study was performed to investigate the efficacy and side effects including changes in lipid profiles of combining anti-aromatase therapy and COX-2 inhibitor preoperatively in hormone sensitive postmenopausal breast cancers.

METHODS

From February 2002 to April 2003, 41 postmenopausal women with histologically proven LABC were recruited. The patients were randomly assigned to receive exemestane 25 mg daily and celecoxib 400 mg twice-daily (group A), exemestane 25 mg daily (group B) and letrozole 2.5 mg daily (group C.

RESULTS

Observed clinical response rates were 61.5%, 60% and 54.5% for Groups A-C, respectively, with no pathologic complete response. Cholesterol levels for Group A dropped progressively and a statistical difference was observed between fifth week after operation and preoperative level (P = 0.026). In addition, Group A has significantly lowered cholesterol and LDL levels than Groups B and C after 18 weeks of treatment.

CONCLUSION

The initial results show that different neoadjuvant anti-aromatase therapies has similar efficacy but the combination with celecoxib may have an advantageous effects on the serum lipid profiles.

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.

Use of nonsteroidal antiinflammatory drugs and risk of breast cancer: the Case-Control Surveillance Study revisited

Several studies have suggested that use of nonsteroidal antiinflammatory drugs (NSAIDs) may reduce the risk of breast cancer. Reductions in risk may vary according to the hormone receptor status of the tumor or the type of NSAID used. The authors extended a previous US hospital-based case-control study (the Case-Control Surveillance Study) to include 444 additional cases, for a total of 7,006 incident breast cancer cases (1976-2002). They examined the relation between regular NSAID use and breast cancer risk using logistic regression to adjust for confounding. The odds ratio for regular use of NSAIDs was 0.78 (95% confidence interval: 0.63, 0.97), and a trend of decreasing risk with increasing duration of use was statistically significant (p for trend = 0.02). The inverse association with regular use of NSAIDs was stronger among premenopausal women (odds ratio = 0.62). The overall odds ratios for regular use of aspirin and ibuprofen were 0.86 and 0.85, respectively. The effect of NSAID use on breast cancer risk did not vary according to the hormone receptor status of the tumor. In conclusion, long-term regular use of NSAIDs was associated with decreased risk of breast cancer. The type of NSAID used or the hormone receptor status of the tumor did not modify the effect.

Nonsteroidal anti-inflammatory drug use and breast cancer risk by stage and hormone receptor status

BACKGROUND

Epidemiologic studies of the association between nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, and breast cancer risk have yielded inconsistent results. We investigated the association of NSAID use with risk of breast cancer in the California Teachers Study cohort, with special attention to risk of specific breast cancer subtypes and to type of NSAID used.

METHODS

We analyzed data on 114 460 women in the California Teachers Study cohort who were aged 22 to 85 years and free of breast cancer at baseline in 1995 to 1996. Information on frequency and duration of NSAID use was collected through a self-administered questionnaire. A total of 2391 women were diagnosed with breast cancer during the follow-up period from 1995 to 2001. We used Cox proportional hazards regression to estimate relative risks (RR) and 95% confidence intervals (CI) of breast cancer subtypes with NSAID use.

RESULTS

Neither regular use (more than once a week) of any NSAID (aspirin and ibuprofen combined) nor regular use of aspirin was associated with breast cancer risk (RR = 1.09, 95% CI = 0.97 to 1.21 for daily versus no regular use of NSAIDs and RR = 0.98, 95% CI = 0.86 to 1.13 for daily versus no regular use of aspirin). However, long-term (> or = 5 years) daily aspirin users had a non-statistically significant decreased risk of estrogen receptor and progesterone receptor (ER/PR)-positive breast cancer (RR = 0.80, 95% CI = 0.62 to 1.03). In contrast, we observed a statistically significantly increased risk of ER/PR-negative breast cancer with long-term daily use of aspirin (RR = 1.81, 95% CI = 1.12 to 2.92). In this population, 11 fewer ER/PR-positive breast cancer cases and seven excess ER/PR-negative breast cancer cases may be due to daily long-term aspirin use among 2391 breast cancer cases observed over 6 years if the association were proven to be causal. Long-term daily use of ibuprofen was also associated with an increased risk of breast cancer (RR = 1.51, 95% CI = 1.17 to 1.95), particularly of nonlocalized tumors (RR = 1.92, 95% CI = 1.24 to 2.97). If causality were subsequently proven, 16 of the observed 2391 breast cancer cases and 8 of the 713 non-localized breast cancer cases would be attributable to long-term daily use of ibuprofen.

CONCLUSIONS

Long-term daily use of NSAIDs was not associated with breast cancer risk overall. Ibuprofen use was associated with an increased risk of breast cancer, and long-term daily aspirin use was associated with an increased risk of ER/PR-negative breast cancer. However, it is not clear if the observed association is causal.

COX-2 expression in DCIS: correlation with VEGF, HER-2/neu, prognostic molecular markers and clinicopathological features

AIMS

There is considerable evidence that links COX-2 to the development of cancer. The aim of our study was to assess, by immunohistochemistry, COX-2 expression in ductal carcinoma in situ (DCIS) and its possible correlation with HER-2/neu, vascular endothelial growth factor (VEGF) expression and other common immunohistochemical parameters (p53, ER, PGR, Ki67).

METHODS AND RESULTS

Tissue samples of 49 archival cases of DCIS without any invasive component were analysed for COX-2, HER-2/neu, VEGF, oestrogen and progesterone receptors, Ki67 and p53 by immunohistochemistry using specific antibodies. COX-2 expression was detected in 43 (87.8%) tissue samples, of which 12 (24.5%) were graded as weak, 22 (44.9%) as moderate and nine (8.4%) as high expression. Only six (12.2%) lesions were negative for COX-2 expression. VEGF expression was detected in 93.8% of samples; 66.7% of lesions were found to be positive for HER-2/neu expression. Furthermore, COX-2 expression was significantly correlated with VEGF expression (P = 0.003). A significant positive correlation was also observed between COX-2 and HER-2/neu expression (P < 0.0001).

CONCLUSIONS

Our results suggest that COX-2 is highly expressed in DCIS and takes part in the molecular pathway implicated in progression of breast cancer and may provide a rationale for targeting COX-2 in preinvasive breast cancer therapy.

Cyclooxygenase inhibitors suppress aromatase expression and activity in breast cancer cells

Estradiol is biosynthesized from androgens by the aromatase enzyme complex. Previous studies suggest a strong association between aromatase (CYP19) gene expression and the expression of cyclooxygenase (COX) genes. Our hypothesis is that higher levels of COX-2 expression result in higher levels of prostaglandin E2, which, in turn, increases CYP19 expression through increases in intracellular cAMP levels. This biochemical mechanism may explain the beneficial effects of nonsteroidal antiinflammatory drugs on breast cancer. The effects of nonsteroidal antiinflammatory drugs, COX-1 and COX-2 selective inhibitors on aromatase activity and expression were studied in human breast cancer cells. The data from these experiments revealed dose-dependent decreases in aromatase activity after treatment with all agents. Real-time PCR analysis of aromatase gene expression showed a significant decrease in mRNA levels when compared with control for all agents. These results were consistent with enzyme activity data, suggesting that the effect of COX inhibitors on aromatase begins at the transcriptional level. Exon-specific real-time PCR studies suggest that promoters I.3, I.4, and II are involved in this process. Thus, COX inhibitors decrease aromatase mRNA expression and enzymatic activity in human breast cancer cells in culture, suggesting that these agents may be useful in suppressing local estrogen biosynthesis in the treatment of hormone-dependent breast cancer.

Translational studies on aromatase, cyclooxygenases, and enzyme inhibitors in breast cancer

Aromatase expression and enzyme activity in breast cancer patients is greater in or near the tumor tissue compared with the normal breast tissue. Regulation of aromatase expression in human tissues is quite complex, involving alternative promoter sites that provide tissue-specific control. Previous studies in our laboratories suggested a strong association between aromatase (CYP19) gene expression and the expression of cyclooxygenase (COX) genes. Our hypothesis is that higher levels of COX expression result in higher levels of prostaglandin E2 (PGE2), which in turn increases CYP19 expression through increases in intracellular cyclic AMP levels. This biochemical mechanism may explain the beneficial effects of non-steroidal anti-inflammatory drugs (NSAIDs) on reducing the risks of breast cancer. The effects of NSAIDs (ibuprofen, piroxicam, and indomethacin), a COX-1 selective inhibitor (SC-560), and COX-2 selective inhibitors (celecoxib, niflumic acid, nimesulide, NS-398, and SC-58125) on aromatase activity and CYP19 expression were investigated in breast cancer cell culture systems. Dose-dependent decreases in aromatase activity were observed following treatment with an NSAID or COX inhibitor, with the most effective agents being COX selective inhibitors. Real time PCR analysis of aromatase gene expression showed a significant decrease in mRNA levels in treated cells when compared to vehicle control. These results suggest that the effect of COX inhibitors on aromatase occurs at the transcriptional level. To further probe these interactions, short interfering RNAs (siRNA) were designed against either human CYP19 mRNA or human COX-2 mRNA. Treatment of breast cancer cells with aromatase siRNAs suppressed CYP19 mRNA and aromatase enzyme activity. Finally, treatment with COX-2 siRNAs downregulated the expression of COX-2 mRNA; furthermore, the siCOX-2-mediated suppression of COX-2 also resulted in suppression of aromatase mRNA. In summary, pharmacological regulation of aromatase and cyclooxygenases can act locally in an autocrine fashion to decrease the biosynthesis of estrogen and may provide additional therapy options for patients with hormone-dependent breast cancer.

Early neoplastic progression is complement independent

Infiltration of leukocytes into premalignant tissue is a common feature of many epithelial neoplasms and is thought to contribute to cancer development. However, the molecular and cellular regulatory mechanisms underlying activation of innate host responses to enhanced neoplastic cell proliferation are largely unknown. Considering the importance of the complement system in regulating inflammation during acute pathologic tissue remodeling, we examined the functional significance of complement component 3 (C3) as a regulator of inflammatory cell infiltration and activation during malignant progression by using a transgenic mouse model of multistage epithelial carcinogenesis, e.g., HPV16 mice. Whereas abundant deposition of C3 is a characteristic feature of premalignant hyperplasias and dysplasias coincident with leukocyte infiltration in neoplastic tissue, genetic elimination of C3 neither affects inflammatory cell recruitment toward neoplastic skin nor impacts responding pathways downstream of inflammatory cell activation, e.g., keratinocyte hyperproliferation or angiogenesis. Taken together, these data suggest that complement-independent pathways are critical for leukocyte recruitment into neoplastic tissue and leukocyte-mediated potentiation of tumorigenesis.

Association of regular aspirin use and breast cancer risk

Of the limited number of epidemiological investigations on aspirin (and other nonsteroidal anti-inflammatory drugs) and breast cancer, the majority observe a protective role, yet only a few report dose-response effects for frequency or duration of use. We studied aspirin use among 1,478 breast cancer patients diagnosed from 1982 to 1998, and 3,383 cancer-free hospital controls at the Roswell Park Cancer Institute. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression. Compared to never use,both regular (> or =1 tablet per week for > or =1 year) and occasional use were inversely associated with breast cancer (adjusted OR = 0.84, 95% CI 0.64-0.97; adjusted OR = 0.80, 95% CI 0.67-0.96, respectively). Among regular users, an inverse trend was found for number of tablets consumed per week (1, 2-6, or > or =7) with corresponding ORs of 0.95, 0.80, and 0.74 (P(trend) = 0.01). Daily use spanning 10 or more years was associated with a more pronounced reduction in risk (P(trend) = 0.005). Our findings corroborate the growing body of observational evidence that regular aspirin use may be associated with reduced risk of breast cancer.

Aspirin and Other Nonsteroidal Anti-inflammatory Drugs and Breast Cancer Incidence in a Large U.S. Cohort

Use of nonsteroidal anti-inflammatory drugs (NSAIDs), particularly aspirin, has consistently been associated with reduced risk of breast cancer in case-control studies. However, results from prospective studies have been less consistent. We examined the association between NSAID use and breast cancer incidence, adjusting for multiple breast cancer risk factors among 77,413 women in the Cancer Prevention Study II Nutrition Cohort. During follow-up from 1992 to 2001, we observed 3,008 cases of incident breast cancer. Information on NSAID use was obtained from a questionnaire completed at enrollment in 1992 or 1993 and was updated using follow-up questionnaires in 1997 and 1999. NSAID use was modeled using time-dependent variables to update exposure status. Neither current total NSAID use (aspirin and other NSAIDs combined) nor current aspirin use were associated with breast cancer incidence even at relatively high levels of use [rate ratio (RR), 1.07; 95% confidence interval (95% CI), 0.96-1.21 for ≥60 NSAID pills per month compared with no reported use of NSAIDs; RR, 1.01; 95% CI, 0.84-1.20 for ≥60 aspirin per month compared with no reported use of aspirin]. Even long-duration regular use (≥30 pills per month for ≥5 years) was not associated with breast cancer incidence (RR, 1.05; 95% CI, 0.88-1.26 for total NSAIDs; RR, 0.88; 95% CI, 0.69-1.12 for aspirin). Although we cannot exclude a small reduction in breast cancer risk associated with NSAID use, the results of this study provide evidence against a large reduction in risk.

Risk Assessment: Controversies and Management of Moderate- to High-Risk Individuals

With the current understanding of sporadic and familial breast cancer, it is now possible to identify individuals who have a moderate or high risk of breast cancer. For these individuals, it is useful to perform formal cancer risk assessment and develop an individualized risk reduction plan, including a tailored plan for cancer screening, preventive therapy, and/or prophylactic surgery. Assessment using a predictive model such as the Gail model is particularly useful in individuals at increased risk for sporadic breast cancer. In addition, assessment of risk based on histologic appearance of benign or premalignant breast lesions can be used to identify individuals for whom more aggressive risk reduction strategies are warranted. For individuals who are at risk for familial cancer syndromes, other predictive models are more appropriate. For this extremely high-risk group, genetic testing for mutations in familial cancer susceptibility genes is helpful to identify individuals who would benefit from even more aggressive cancer risk reduction strategies. Strategies to identify the levels of risk for breast cancer, including the identification of moderate, high, or very high risk groups are discussed. Management options for these groups are presented, including who to consider for more aggressive screening, chemoprevention, or prophylactic surgery. Current recommendations for screening, chemoprevention, and surgery for each risk group are presented. The ability to identify individuals at high risk for breast cancer now enables clinicians to intervene to reduce the risk of breast cancer. Aggressive screening, preventive therapy, and prophylactic surgery in moderate- to high-risk individuals should, in the future, significantly reduce the incidence of invasive breast cancer.

A population-based cohort study of mortality among users of ibuprofen in Denmark

Using the population-based Pharmacoepidemiologic Prescription Database of North Jutland County, Denmark, we identified 113,538 persons who filled prescriptions for ibuprofen during 1989 through 1995 and determined subsequent mortality through 1996. Standardized mortality ratios [SMRs] for 25 specific causes of death were computed compared with the general population. SMRs were elevated for most causes of death, with an overall SMR of 1.21 (95% confidence interval 1.19-1.24) among persons who filled prescriptions for ibuprofen. There was a nearly threefold increase in the number of deaths from gastrointestinal bleeding within 1 year of ibuprofen prescription but no concomitant increase in hemorrhagic stroke. Elevated SMRs were seen for several cancer types, although the mortality ratios were highest within 1 year of prescription and declined with longer follow-up. For colon cancer, SMRs were below 1.0 three or more years after ibuprofen prescription. For hypertensive disease, nonhemorrhagic stroke, and diabetes, we observed slight but significant elevations of the SMRs that persisted beyond the fifth year of follow-up. Our findings indicate a slight increase in overall mortality among persons receiving ibuprofen on prescription. This excess was greatest within the first year, due partially to ibuprofen-related gastrointestinal bleeding but mostly to elevated cancer mortality among ibuprofen users. This temporal pattern is characteristic of an effect of confounding by indication, with ibuprofen being used for pain relief by patients with imminent fatal illnesses such as cancer. The slight excess mortality that persisted beyond the first few years was largely due to elevated death from hypertensive disease and diabetes, which may be explained in part by increased prescription of ibuprofen to patients with long-standing medical problems.

Cyclooxygenase-2: a potential target in breast cancer

Use of nonsteroidal anti-inflammatory drugs has been shown to result in a 40% to 50% reduction in the relative risk of developing colorectal cancer. Cyclooxygenase-2 (COX-2) overexpression occurs in 43% of human invasive breast cancers and 63% of ductal carcinomas in situ. There is considerable in vitro, animal model, and epidemiologic evidence to suggest that COX-2 may play some role in breast tumor initiation and progression. PGE(2) is a major downstream mediator of COX-2 that promotes cellular proliferation and angiogenesis, makes cells resistant to apoptosis, enhances invasiveness, and modulates immunosuppression. COX-2 and COX-2-derived PGE(2) may be involved in mammary carcinogenesis. Therefore, COX-2 selective inhibitors may have a role in breast cancer prevention.

Growth inhibition of breast epithelial cells by celecoxib is associated with upregulation of insulin-like growth factor binding protein-3 expression

Several experimental and epidemiological studies have suggested a role for the use of cyclooxygenase (COX)-2 inhibitors in the prevention of breast cancer. The relative lack of toxicity associated with these compounds favors their use as chemopreventive agents, but the underlying mechanism of their chemopreventive effect remains unclear. We have observed that the COX-2 inhibitor celecoxib inhibits growth and induces apoptosis in the immortalized breast epithelial cell line 184htert. Microarray gene expression analysis of 184htert cells treated with 50 microM celecoxib for 6h revealed the modulation of several genes of interest, including a significant induction of expression of the mRNA encoding insulin-like growth factor binding protein-3 (IGFBP-3). IGFBP-3 is a potent pro-apoptotic protein and growth inhibitor of breast cancer cells, which acts mainly by inhibiting the access of the mitogens IGF-I and IGF-II to their cell surface receptor, but also via IGF-independent effects. Quantitative real-time RT PCR demonstrated that 50 microM celecoxib induced a approximately 3-fold increase in expression of IGFBP-3 mRNA after 6h. Furthermore, ligand blot analysis revealed that celecoxib treatment was associated with the upregulation of IGFBP-3 at the protein level. IGFBP-3 (500 ng/ml) treatment of 184htert cells inhibited IGF-I and serum-induced proliferation, but had no effect on cell growth under serum-free conditions, indicating that IGF-independent effects of IGFBP-3 are not observed in this system. Our results suggest that celecoxib may decrease IGF-I-associated breast cancer risk by a mechanism involving induction of expression of IGFBP-3 and subsequent reduced proliferation of at-risk breast epithelial cells.

Invasive and angiogenic phenotype of MCF-7 human breast tumor cells expressing human cyclooxygenase-2

To evaluate the direct effect of human cyclooxygenase-2 (hCox-2) on human breast tumor cell proliferation, invasion, and angiogenesis, hCox-2 cDNA was transfected into slow growing, non-metastatic MCF-7 human breast tumor cells that express low levels of Cox-2. Two stable transfectant clones, designated MCF-7/hCox-2 clones 8 and 10, had significantly decreased (P < 0.05) doubling time, with two-fold greater number of cells during exponential growth compared to the MCF-7/vector control. Proliferation of both of the MCF-7/hCox-2 clones was significantly inhibited in a time- and dose-dependent manner by celecoxib. The MCF-7/hCox-2 clones 8 and 10 formed larger and greater numbers of colonies in soft agar than the MCF-7/vector control, with a corresponding increased invasion across an artificial Matrigel basement membrane in response to recombinant human epidermal growth factor (hEGF). The MCF-7/hCox-2 clones 8 and 10 had higher mRNA levels of two splice variants of vascular endothelial growth factor (VEGF), V145 and V165. These results demonstrate that hCox-2 directly increases breast tumor cell proliferation, stimulates invasion across a basement membrane, and induces synthesis of specific heparin binding splice variants of VEGF.

Histologically normal human mammary epithelia with silenced p16(INK4a) overexpress COX-2, promoting a premalignant program

Breast tissue from healthy women contains variant mammary epithelial cells (vHMEC) exhibiting p16INK4a promoter hypermethylation both in vivo and in vitro. When continuously cultured, vHMEC acquire telomeric dysfunction and produce the types of chromosomal abnormalities seen in premalignant lesions of cancer. We find that late passage vHMEC express elevated prostaglandin cyclo-oxygenase 2 (COX-2), which contributes to increased prostaglandin synthesis, angiogenic activity, and invasive ability. These data demonstrate the existence of human mammary epithelial cells with the potential to acquire multiple genomic alterations and phenotypes associated with malignant cells. Moreover, COX-2 overexpression coincides with focal areas of p16INK4a hypermethylation in vivo, creating ideal candidates as precursors to breast cancer. These putative precursors can be selectively eliminated upon exposure to COX-2 inhibitors in vitro.

Lack of prognostic effect of Cox-2 expression in primary breast cancer on short-term follow-up

AIMS

Cyclo-oxygenase (Cox) catalyses the conversion of arachidonic acid into prostaglandins (PG) and other eciosanoids. The prostaglandins, especially PGE(2) are implicated in tumorigenesis via angiogenesis and suppression of immune reactivity. There are two known isoforms of the enzyme, Cox-1, which is constitutively expressed and the inducible isoform, Cox-2. Cox-2 is induced in response to inflammatory mediators, growth factors, oncogenes and mitogens. Non-selective Cox inhibitors may reduce the relative risk of colonic and breast carcinoma.

METHODS

We studied the expression of Cox-2 by immunohistochemistry in 106 primary breast carcinoma specimens collected over a three-year period, using a commercially available polyclonal antibody on formalin-fixed, paraffin-embedded tissue. The slides were examined independently by two pathologists. Tumours were classified according to accepted criteria and an immunohistochemical score (IHS) was calculated for each specimen. The IHS combines the percentage of immunoreactive cells (quantity score) and an estimate of staining intensity (staining intensity score).

RESULTS

All patients were female. The mean age was 53 years, range 28-86 years. Forty percent (n=42) of tumours were node negative and 60% (n=64) node positive. Forty-nine percent (n=52) of tumours were grade 3, a further 49% (n=52) grade 2 and 2% (n=2) grade 1. There was no statistically significant correlation between IHS and tumour size, grade, histology, nodal status, estrogen receptor or progesterone receptor positivity. A trend was observed showing an IHS of zero is associated with prolonged survival compared with an IHS of 9-12.

CONCLUSION

Cox-2 expression in primary breast cancer does not correlate with accepted pathological or biochemical prognostic indicators.

Effects of non-steroidal anti-inflammatory drugs on cancer sites other than the colon and rectum: a meta-analysis

Background

Observational studies have consistently shown that aspirin and non-steroidal anti-inflammatory drug (NSAID) use is associated with a close to 50% reduced risk of colorectal cancer. Studies assessing the effects of NSAIDs on other cancers have shown conflicting results. Therefore, we conducted a meta-analysis to evaluate the relationship between NSAID use and cancer other than colorectal.

Methods

We performed a search in Medline (from 1966 to 2002) and identified a total of 47 articles (13 cohort and 34 case-control studies). Overall estimates of the relative risk (RR) were calculated for each cancer site using random effects models.

Results

Aspirin use was associated with a reduced risk of cancer of the esophagus and the stomach (RR, 0.51; 95%CI (0.38–0.69), and 0.73; 95%CI (0.63–0.84)). Use of NSAIDs was similarly associated with a lower risk of esophageal and gastric cancers (RR,0.65; 95% CI(0.46–0.92) and RR,0.54; 95%CI (0.39–0.75)). Among other cancers, only the results obtained for breast cancer were fairly consistent in showing a slight reduced risk among NSAID and aspirin users (RR, 0.77; 95%CI (0.66–0.88), and RR, 0.77; 95%CI (0.69–0.86) respectively)).

Conclusions

The results of this meta-analysis show that the potential chemopreventive role of NSAIDs in colorectal cancer might be extended to other gastrointestinal cancers such as esophagus and stomach. Further research is required to evaluate the role of NSAIDs at other cancers sites.

Celecoxib anti-aromatase neoadjuvant (CAAN) trial for locally advanced breast cancer: preliminary report

Anti-aromatase therapy is important in the treatment of breast cancer in postmenopausal women. Cyclooxygenase-2 (COX-2) inhibitors have been shown to be effective in chemoprevention in animal and clinical studies. A proof of principle study was performed to investigate the efficacy of combing anti-aromatase therapy (exemestane) and COX-2 inhibitors neoadjuvantly in hormone-sensitive postmenopausal breast cancers. The initial results are reported. The patients were randomly assigned to receive exemestane 25 mg daily and celecoxib 400 mg twice daily (group A), exemestane 25 mg daily (group B) and letrozole 2.5 mg daily (group C). The analysis was based on 20 patients who received at least one cycle of treatment. Fourteen patients completed two cycles and 12 patients three cycles. All groups showed clinical response and there was decrease in tumor area in each group. However, complete clinical response was only observed for group A patients. There was also progressive decline in blood CEA and CA15.3 levels but the differences between the three groups were not significant. The results of the preliminary analysis are encouraging but definitive conclusion could only be drawn after the completion of the study.

Development of COX inhibitors in cancer prevention and therapy

On the strength of in vitro, in vivo, observational, and clinical data, nonsteroidal antiinflammatory drugs (NSAIDs)-also referred to as COX inhibitors-have emerged as lead compounds for cancer prevention, and possible adjuncts to cancer therapy. Thus far, the routine use of NSAIDs for these indications is limited, largely owing to toxicity concerns, the paucity of efficacy data for any specific target organ, and uncertainties with regard to the most appropriate regimen (i.e., the best agent, formulation, dose, route of administration, and duration). Strategies to address these concerns primarily aim to improve the therapeutic index (i.e., benefit:risk ratio) of COX inhibitors by 1) minimizing systemic exposures whenever feasible, 2) achieving greater mechanistic specificity, 3) coadministering agents that provide prophylaxis against common toxicities, and 4) coadministering other effective anticancer agents. Clinical trials testing most of these strategies have been completed or are under way. The National Cancer Institute has a substantial research portfolio dedicated to the identification, testing, and development of NSAIDs as preventive and therapeutic anticancer agents. Discovering how to apply NSAIDs in persons with-or at risk for-cancer, although challenging, has the potential for considerable clinical and public health benefits.