Breast cancer risk in a large cohort of female antidepressant medication users

The incidence risk of breast and gynecological cancer by antidepressant use: A systematic review and dose–response meta-analysis of epidemiological studies involving 160,727 patients

Background and objective

Antidepressants are widely prescribed to treat depression and anxiety disorders that may become chronic conditions among women. Epidemiological studies have yielded inconsistent results on the correlation between antidepressant use and the incidence risk of female breast and gynecological cancer, along with uncertain dose–response relationship. Therefore, we performed a systematic review and dose–response meta-analysis to investigate the association.

Methods

Web of Science, Embase, PubMed, The Cochrane Library, and PsycINFO were systematically searched in January 2022, with no language limits. Random-effect models were used to calculate pooled effect sizes and 95% confidence intervals between studies. Linear and non-linear dose–response analyses were performed to evaluate the dose or duration of antidepressant use affecting the incidence risk of female breast and gynecological cancer. Further subgroup analyses were systematically performed by stratifying almost all study characteristics and important potential confounders, in order to further clarify and validate the important potential hypotheses regarding the biological mechanism underlying this association.

Results

Based on a systematic literature search, 34 eligible studies (27 case–control studies and 7 cohort studies) involving 160,727 female breast and gynecological cancer patients found that antidepressant use did not increase the incidence risk of female breast and gynecological cancer (pooled OR: 1.01; 95% CI: 0.97, 1.04, I² = 71.5%, p < 0.001), and even decreased the incidence risk of ovarian cancer (pooled OR: 0.91; 95% CI: 0.83, 1, I² = 17.4%, p = 0.293). There were a non-linear dose–response relationship (p non-linearity < 0.05) between the duration of antidepressant use and incidence risk of female breast cancer, and an inverse linear dose–response relationship between antidepressant use and the incidence risk of gynecological cancer, specifically with an increase of cumulative defined daily dose or duration to a high level, like 25,550 doses (OR: 0.91, 95% CI: 0.85–0.98, p linearity < 0.05) or 4,380 days (OR: 0.82; 95% CI: 0.7, 0.96, p linearity < 0.05), compared to never antidepressant users.

Conclusion

This systematic review and dose–response meta-analysis found that antidepressant use did not increase the incidence risk of female breast and gynecological cancer and even decreased the incidence risk of ovarian cancer, along with a non-linear or linear dose–response relationship.

Systematic Review Registration

PROSPERO https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=313364, identifier CRD42022313364.

Antidepressants in association with reducing risk of oral cancer occurrence: a nationwide population-based cohort and nested case-control studies

Objectives

Several studies suggested that antidepressant use may increase or decrease the risk of cancer occurrence, depending on specific cancer types. The possible carcinogenic effect of antidepressants has received substantial attention; however, evidence remains inconclusive. Here we investigated associations between the use of antidepressants and occurrences of oral cancer (OC).

Methods

Two million samples were randomly collected from the National Health Insurance Research Database in Taiwan, which covers 98% of the total population (23 million). All patients from2000 to 2009 were followed up. We identified 5103 patients newly diagnosed with OC after antidepressants use in addition to 20,412 non-OC matched subjects and 95,452 unmatched non-OC subjects.

Results

In nested case control analysis, factors associating with OC, including age [OR = 1.02; 95% confidence interval (CI) = 1.01–1.03) and male (OR = 5.30; 95% CI = 4.92–5.70) were independently associated with increased risk of OC. Based on the functions of antidepressants, antidepressants treatment medications were further classified to investigate risk of OC. Selective serotonin reuptake inhibitors (OR = 0.61; 95% CI = 0.53–0.70) and tricyclic antidepressants (OR = 0.57; 95% CI = 0.52–0.63) were associated with reduced risk of OC. The risk of developing OC among subjects taking antidepressants was less than 26% [hazard ratio (HR) =0.74; 95% CI = 0.68–0.81] in prospective cohort study. The effect of a cumulative duration and dose was a significantly reduced risk of OC.

Conclusions

The association between antidepressant use and decreasing OC risk were demonstrated by both prospective and nested case–control studies.

The effect of ethanolic extract of Thymus kotschyanus on cancer cell growth in vitro and depression-like behavior in the mouse

Cancer and depression are known as two of the most debilitating disease and disorder increasing evidence suggest an urgent need for new therapeutic agents with lower toxicity and high efficacy. Some Thyme species extracts have remarkably been shown to positively affect depression and cancer cells. In the present study, we investigated the effect of Thymus kotschyanus on depression and cancer cells. To this end, in experiment 1, NMRI mice were treated orally with the ethanolic extract of T. kotschyanus (50, 150 and 250 mg/ml) for seven days and then depression-like behavior was measured by Forced Swim Test (FST) and Tail Suspension Test (TST). In experiment 2, the pharmacological effect of the extract on the lung (A549) and cervical (Hela) cancer cell lines was also evaluated by MTT (3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide) in various concentration_(10, 5, 2.5, 1.25, 0.63, 0.31, 0.15 and 0.08 mg/ml). The results indicated that T. kotschyanus extract treatment (150 and 250 mg/kg) decreased depression-like behavior in the FST and TST tests in adult mice. Moreover, the treatment inhibited cancer cell growth and viability in a dose and time-dependent manner. Collectively these findings suggest that T. kotschyanus have antidepressant and anticancer effects.

Depression, Antidepressant Use, and Postmenopausal Breast Cancer Risk

BACKGROUND

Whether depression and antidepressant (AD) use might influence breast cancer risk is unclear, and these exposures have not been evaluated together in a single, prospective cohort study of breast cancer risk.

METHODS

Among 71,439 postmenopausal women in the Women's Health Initiative Observational Study (WHI-OS), we estimated multivariable-adjusted HRs for the independent and joint effects of depressive symptoms and AD use on breast cancer risk using Cox proportional hazards regression.

RESULTS

When analyzed separately, neither depressive symptoms nor AD use at baseline were associated with a significantly increased risk of total breast cancer (HR = 0.96, 95% CI, 0.85-1.08; HR = 1.04, 95% CI, 0.92-1.20, respectively) or invasive breast cancer (HR = 0.98, 95% CI, 0.86-1.12; HR = 1.00, 95% CI, 0.86-1.16, respectively). Current AD use was associated with a borderline-significant increase of in situ breast cancer (HR = 1.30, 95% CI, 0.99-1.75) after adjustment for depressive symptoms; however, this relationship was attenuated after adjustment for mammographic screening (HR = 1.08, 95% CI, 0.76-1.51). No significant variation in total breast cancer risk was observed when the separate and joint effects of depressive symptoms and AD use were explored (P for interaction = 0.14).

CONCLUSION

We found no evidence that either depression or AD use influences breast cancer risk. An elevated risk of in situ disease among AD users could not be ruled out, though is likely due to increased screening in this subgroup.

IMPACT

Given the high prevalence of these exposures, these results may provide reassurance to the millions of women who are depressed and/or use ADs each year.

Anti-depressant therapy and cancer risk: a nested case-control study

Previous studies demonstrated a possible association between anti-depressant therapy with selective serotonin reuptake inhibitors (SSRI) and tricyclic anti-depressants (TCA), several genetic and hormonal pathways and cancer risk, with inconsistent results. Exposure to serotonin-norepinephrine reuptake inhibitors (SNRI) was not studied extensively. We sought to evaluate the association between exposure to SSRIs, TCAs and SNRIs and the five most common solid tumors. We conducted nested case-control studies using a large UK population-representative database. Cases were those with any medical code for the specific malignancy. For every case, four controls matched on age, sex, practice site, and duration of follow-up before index date were selected using incidence-density sampling. Exposure of interest was SSRI, SNRI or TCA therapy before index date. Odds ratios (ORs) and 95% CIs were estimated for each anti-depressant class using conditional logistic-regression analysis, adjusted for potential confounders, such as obesity, smoking history and alcohol consumption.

RESULTS

109,096 cancer patients and 426,402 matched controls were included. Current SSRI users with treatment initiation>one year before index date had modestly higher risk for lung and breast cancers with ORs of 1.27 (95% CI 1.16-1.38) and 1.12 (95% CI 1.06-1.18), respectively. Among current TCA users, there was a higher risk only for lung cancers with OR of 1.45 (95% CI 1.31-1.6). There was no statistically significant association between current SNRI therapy and cancer risk.

DISCUSSION

Treatment with SSRI and TCA might be associated with increased lung cancer risk. SSRI therapy might be associated with modest increase in breast cancer risk.

A systematic review of non-hormonal treatments of vasomotor symptoms in climacteric and cancer patients

The cardinal climacteric symptoms of hot flushes and night sweats affect 24-93% of all women during the physiological transition from reproductive to post-reproductive life. Though efficacious, hormonal therapy and partial oestrogenic compounds are linked to a significant increase in breast cancer. Non-hormonal treatments are thus greatly appreciated.

This systematic review of published hormonal and non-hormonal treatments for climacteric, and breast and prostate cancer-associated hot flushes, examines clinical efficacy and therapy-related cancer risk modulation.

A PubMed search included literature up to June 19, 2014 without limits for initial dates or language, with the search terms, (hot flush* OR hot flash*) AND (clinical trial* OR clinical stud*) AND (randomi* OR observational) NOT review). Retrieved references identified further papers. The focus was on hot flushes; other symptoms (night sweats, irritability, etc.) were not specifically screened. Included were some 610 clinical studies where a measured effect of the intervention, intensity and severity were documented, and where patients received treatment of pharmaceutical quality. Only 147 of these references described studies with alternative non-hormonal treatments in post-menopausal women and in breast and prostate cancer survivors; these results are presented in Additional file 1.

The most effective hot flush treatment is oestrogenic hormones, or a combination of oestrogen and progestins, though benefits are partially outweighed by a significantly increased risk for breast cancer development.

This review illustrates that certain non-hormonal treatments, including selective serotonin reuptake inhibitors, gabapentin/pregabalin, and Cimicifuga racemosa extracts, show a positive risk-benefit ratio.

Key points

Several non-hormonal alternatives to hormonal therapy have been established and registered for the treatment of vasomotor climacteric symptoms in peri- and post-menopausal women.

There are indications that non-hormonal treatments are useful alternatives in patients with a history of breast and prostate cancer. However, confirmation by larger clinical trials is required.

Is amisulpride safe when prescribed to breast and prostate cancer patients?

In the last decades, the potential association between antidepressants and cancer risk has been increasingly investigated. Fundamental researches, performed on animal models and cell tumoral lines, have highlighted several biological mechanisms possibly supporting this association. Nevertheless, the epidemiological studies investigating the risk of cancer in patients receiving selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) have provided conflicting and inconclusive results. Therefore, the prescription of several antidepressants in oncologic patients still remains a matter of discussion. The aim of this review is to present and discuss available evidence concerning the association between the risk of breast and prostate cancer and the use of antidepressant medications. Thus, consistencies, differences, and contradictions of available data are reported. A special focus is addressed to amisulpiride, a widely prescribed drug still poorly investigated with regard to the risk of cancer occurrence and recurrence. Overall, there is no definitive evidence of increased risk of breast and prostate cancer among patients exposed to SSRIs and TCAs. The association between amisulpiride and cancer risk has been to date scarcely explored and considered in clinical settings. Nevertheless, the hyperprolactinemia frequently resulting from its adoption has been repeatedly associated, to increased cancer risk and poorer prognosis in cancer patients. Thus, the use of amisulpiride among cancer patients should be carefully considered.

Selective Serotonin Reuptake Inhibitor (SSRI) Antidepressants, Prolactin and Breast Cancer

Selective serotonin reuptake inhibitors (SSRIs) are a widely prescribed class of antidepressants. Laboratory and epidemiologic evidence suggests that a prolactin-mediated mechanism secondary to increased serotonin levels at neuronal synapses could lead to a potentially carcinogenic effect of SSRIs. In this population-based case-control study, we evaluated the association between SSRI use and breast cancer risk as a function of their relative degree of inhibition of serotonin reuptake as a proxy for their impact on prolactin levels. Cases were 2,129 women with primary invasive breast cancer diagnosed from 2003 to 2007, and controls were 21,297 women randomly selected from the population registry. Detailed information for each SSRI prescription dispensed was compiled using the Saskatchewan prescription database. Logistic regression was used to evaluate the impact of use of high and lower inhibitors of serotonin reuptake and duration of use, as well as to assess the effect of individual high inhibitors on the risk of breast cancer. Exclusive users of high or lower inhibitors of serotonin reuptake were not at increased risk for breast cancer compared with non-users of SSRIs (OR = 1.01, CI = 0.88–1.17 and OR = 0.91, CI = 0.67–1.25 respectively), regardless of their duration of use or menopausal status. While we cannot rule out the possibility of a clinically important risk increase (OR = 1.83, CI = 0.99–3.40) for long-term users of sertraline (≥24 prescriptions), given the small number of exposed cases (n = 12), the borderline statistical significance, and the wide confidence interval, these results need to be interpreted cautiously. In this large population-based case-control study, we found no conclusive evidence of breast cancer risk associated with the use of SSRIs even after assessing the degree of serotonin reuptake inhibition and duration of use. Our results do not support the serotonin-mediated pathway for the prolactin-breast cancer hypothesis.

Use of antidepressants and the risk of breast cancer: a meta-analysis

The goal of this study was to perform a meta-analysis to examine the association between the use of antidepressants (AD) and the risk of breast cancer. We searched the EMBASE and MEDLINE databases from inception through February 25, 2012, using search terms related to ADs and breast cancer. Two evaluators independently reviewed and selected articles and extracted data based on predetermined selection criteria. Pooled effect estimates were obtained by using random- and fixed effects meta-analyses. Of the 3,209 titles identified, 18 articles met the inclusion criteria. The overall risk of breast cancer did not increase among AD users [adjusted odds ratio (aOR) 1.02; 95 % CI 0.96-1.08]. Those who took tricyclic antidepressants (TCAs) or selective serotonin reuptake inhibitors (SSRIs) were not at increased risks of breast cancer. In subgroup meta-analyses, null associations were consistent across the type of AD, funding sources, the number of adjusted variables, medication dose, the ascertainment of exposure, and methodological quality. In subgroup analyses based on exposure duration, a marginal association was observed for the use of SSRIs < 1-2 years (aOR 1.10; 95 % CI 1.02-1.19). However, this effect was attenuated over time and those using SSRIs for more than 1-2 years had no elevated breast cancer risk. These results support the lack of a clinically meaningful association between AD use and the development of breast cancer and provide considerable reassurance. Given that the data collected to date do not support changing the current prescribing patterns for ADs, the important benefits of AD therapy must be considered.

Screening pharmaceuticals for possible carcinogenic effects: initial positive results for drugs not previously screened

OBJECTIVE

To screen commonly used prescription drugs for possible carcinogenic effects.

METHODS

In a large health care program we identified 105 commonly used drugs, not previously screened. Recipients were followed for up to 12½ years for incident cancer. Nested case-control analyses of 55 cancer sites and all combined included up to ten matched controls per case, with lag of at least 2 years between drug dispensing and cancer. Positive associations entailed a relative risk of 1.50, with p ≤ 0.01 and higher risk for three or more, than for one prescription. Evaluation included further analyses, searches of the literature, and clinical judgment.

RESULTS

There were 101 associations of interest for 61 drugs. Sixty-six associations were judged to have involved substantial confounding. We found evidence that of the remaining 35, the following associations may not be due to chance: sulindac with gallbladder cancer and leukemia, hyoscyamine with nonHodgkin lymphoma, nortriptyline with esophageal and hepatic cancer, oxazepam with lung cancer, both fluoxetine and paroxetine with testicular cancer, hydrochlorothiazide with renal and lip cancer, and nifedipine with lip cancer.

CONCLUSIONS

These preliminary findings suggest that further studies are indicated regarding sulindac, hyoscyamine, nortriptyline, oxazepam, fluoxetine, paroxetine, hydrochlorothiazide, and nifedipine.

Antidepressants and breast and ovarian cancer risk: a review of the literature and researchers' financial associations with industry

Background

Antidepressant (AD) use has been purported to increase the risk of breast and ovarian cancer, although both epidemiological and pre-clinical studies have reported mixed results [1]–[6]. Previous studies in a variety of biomedical fields have found that financial ties to drug companies are associated with favorable study conclusions [7].

Methods and Findings

We searched English-language articles in MEDLINE, PsychINFO, the Science Citations Index and the Cochrane Central Register of Controlled Clinical Trials (through November 2010). A total of 61 articles that assessed the relationship between breast and ovarian cancer and AD use and articles that examined the effect of ADs on cell growth were included. Multi-modal screening techniques were used to investigate researchers' financial ties with industry. A random effects meta-analysis was used to pool the findings from the epidemiological literature. Thirty-three percent (20/61) of the studies reported a positive association between ADs and cancer. Sixty-seven percent (41/61) of the studies reported no association or antiproliferative effect. The pooled odds ratio for the association between AD use and breast/ovarian cancer in the epidemiologic studies was 1.11 (95% CI, 1.03–1.20). Researchers with industry affiliations were significantly less likely than researchers without those ties to conclude that ADs increase the risk of breast or ovarian cancer. (0/15 [0%] vs 20/46 [43.5%] (Fisher's Exact test P = 0.0012).

Conclusions

Both the pre-clinical and clinical data are mixed in terms of showing an association between AD use and breast and ovarian cancer. The possibility that ADs may exhibit a bi-phasic effect, whereby short-term use and/or low dose antidepressants may increase the risk of breast and ovarian cancer, warrants further investigation. Industry affiliations were significantly associated with negative conclusions regarding cancer risk. The findings have implications in light of the 2009 USPSTF guidelines for breast cancer screening and for the informed consent process.

A population-based case-control study of Selective Serotonin Reuptake Inhibitors (SSRIs) and breast cancer: the impact of duration of use, cumulative dose and latency

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs), a popular class of antidepressants, may increase breast cancer risk by stimulating the secretion of prolactin, a potential tumour promoter. We evaluated the effects of duration of SSRI use, cumulative dose, and latency on the risk of breast cancer by conducting a population-based case-control study utilizing Saskatchewan health databases.

METHODS

Cases included 1,701 women with primary invasive breast cancer diagnosed from 2003 to 2006, and controls consisted of 17,017 women, randomly selected from the population registry. Use of SSRIs was compiled using the Saskatchewan prescription database. Unconditional logistic regression was conducted to evaluate the impact of duration of combined SSRI use (total number of prescriptions dispensed), cumulative dose (total dosage received) and timing of use (two or more years, two to seven years and more than seven years prior to index date) on the risk of breast cancer.

RESULTS

Overall, SSRI use was not associated with an increased risk of breast cancer regardless of our definition of cumulative use (total number of prescriptions dispensed and total dosage). In addition, our results indicate that prolonged SSRI use does not have a latent effect on breast cancer risk. Also, our findings are not suggestive of an increased risk of breast cancer with the use of individual SSRIs.

CONCLUSIONS

Our study improved upon most previous studies by having a longer follow-up period, a larger sample size of long-term SSRI users and consideration of risk during specific exposure time windows that take latency into account. Given the potential health benefits of using SSRIs, our results suggest that the issue of breast cancer risk may no longer be a concern for women requiring long-term SSRIs.

Incidence of cancer and antidepressant medication: record linkage study

The consumption of antidepressants, especially selective serotonine reuptake inhibitors (SSRI) has been increasing. Because a large fraction of the population is exposed, even a small excess of risk with respect to cancer should be considered. We carried out a record linkage study in Finland utilizing nationwide databases of reimbursed medication and cancer. The study population included all antidepressant drug (AD) users in Finland who had purchased at least 1 prescription between 1998 and 2005, and who had no cancer diagnosis at the date of first purchase. A control population without AD usage (matched by age and sex) was also included. Data consisted of 418,588 pairs of individuals that cumulated 3.3 million person-years with an average of 4.0 years of follow-up. 19,365 cancer cases were observed. The most frequent cancers were breast, prostate, lung, colon, and brain cancer. In general, only few associations between the utilization of AD and cancer could be detected. Over four years exposure to AD showed a weak association with increased colon and breast cancer incidence, which could have been caused by bias. As conclusion, no clear evidence of neither beneficial nor harmful association between usage of antidepressant and cancer was found.

Antidepressant medication use and breast cancer risk

PURPOSE

Most epidemiologic studies have detected no association between prior use of antidepressant medications and breast cancer risk. Despite the uniform conclusion, there is a continuous rise in the proportion of women using antidepressants, lending support to further monitoring of disease effects.

METHODS

We conducted a population-based case-control study among 2908 incident breast cancer cases diagnosed from 2003 to 2006, and 2927 control women from Wisconsin. Associations between antidepressant use and breast cancer risk were evaluated using multivariable logistic regression.

RESULTS

The association between use of antidepressant medications and breast cancer risk was null (OR = 0.89, 95%CI 0.78-1.01). When stratified by type of antidepressant, use of selective-serotonin reuptake inhibitors (SSRIs) resulted in a similar risk overall (OR = 0.85, 95%CI 0.72-1.00) and among former and currents users. There were no associations between other types of antidepressant classes and breast cancer risk. In assessing risks among the five most commonly used antidepressants, we detected no association with fluoxetine, sertraline, venlafaxine, or buproprion hydrochloride. There was a reduction in breast cancer risk of 36% (OR = 0.64, 95%CI 0.45-0.92) among users of paroxetine hydrochloride. When stratified by body mass index, there was a reduction in risk associated with antidepressant users who were not overweight (OR = 0.73, 95% CI 0.60-0.90), but this association was null in overweight women (p-interaction = 0.04).

CONCLUSIONS

Surveillance of health risks associated with antidepressant medications continues to be of public health importance, though these medications are not likely to be associated with breast cancer risk.

Use of common medications and breast cancer risk

Prescription and over-the-counter medications are widely used in the United States and many western countries. More than two-thirds of women ages >45 years, who are at greatest risk for breast cancer, take prescription medication. In light of the ubiquitous nature of medication use and the fact that breast cancer remains the most common cancer in women, research on the role of medication use in breast cancer etiology is warranted. We summarize the epidemiologic evidence on the association between breast cancer risk and use of common medications, including antibiotics, antidepressants, statins, antihypertensives, and nonsteroidal anti-inflammatory drugs. Overall, there is little evidence that would implicate the use of antibiotics, antidepressants, statins, and antihypertensives in the etiology of breast cancer. Although several prospective studies and a randomized low-dose aspirin chemoprevention trial have not shown lower risk of breast cancer among aspirin users, most studies that have examined the potential chemoprotective effect of nonsteroidal anti-inflammatory drugs have shown significant risk reductions for regular and prolonged use of these drugs. The existing literature on the role of medication use in breast carcinogenesis is complicated. Interpretation of the evidence is hampered due to major methodologic differences across studies, including exposure assessment, exposure classification, and adjustment for potential confounding variables. These differences largely stem from the fact that the majority of articles on this topic represent secondary data analyses from studies with inadequate information on exposure or confounders. Thus, future epidemiologic studies specifically designed to study these ubiquitous and biologically plausible exposures are warranted.

Breast cancer recurrence risk in relation to antidepressant use after diagnosis

BACKGROUND

While laboratory data suggest that antidepressants may promote mammary tumor growth, there has been little research investigating whether antidepressant use after breast cancer diagnosis is associated with the risk of breast cancer recurrence.

METHODS

We conducted a retrospective cohort study within Group Health, an integrated healthcare delivery system in Washington state. Women diagnosed with a first primary invasive, stage I, IIA, or IIB, unilateral breast carcinoma between 1990-1994 (aged>or=65 years) and 1996-1999 (aged>or=18 years) were eligible for the study (N=1306). Recurrence within 5-year of diagnosis was ascertained by medical chart review. We used the pharmacy database to identify antidepressant dispensings from Group Health pharmacies. We used multiple Cox regression to estimate the hazard ratio for recurrence and breast cancer mortality, comparing users and non-users of antidepressant medications. Results for recurrence were examined separately in users and non-users of tamoxifen.

RESULTS

We did not observe an association between antidepressant use after breast cancer diagnosis and the risk of recurrence either in general (hazard ratio for any antidepressant use: 0.8; 95% confidence interval: 0.5-1.4) or for specific types of antidepressant medication. Risk of death from breast cancer did not differ between non-users and users of antidepressants.

CONCLUSIONS

The results of this study suggest that women who use antidepressants after breast cancer diagnosis do not have an increased risk of recurrence or mortality.

Prolactin and breast cancer etiology: an epidemiologic perspective

A number of epidemiologic studies of prolactin and breast cancer etiology have recently become available. Retrospective case-control studies have suggested a modest positive or null relationship between circulating prolactin concentrations and risk of breast cancer. However these studies are limited by small sample sizes and the collection of blood after case diagnosis. Several large prospective studies, in which blood was collected prior to diagnosis, have observed modest positive associations between prolactin and risk. In a pooled analysis of approximately 80% of the world's prospective data, the relative risk (RR) comparing women in the top vs bottom quartile of prolactin levels was 1.3 (95% confidence interval (CI): 1.1, 1.6, p-trend = 0.002). The results were similar for premenopausal and postmenopausal women. Most notably, high prolactin levels were associated with a 60% increased risk of estrogen receptor (ER) positive tumors, but not with ER negative tumors. Limited genetic data suggest a role of polymorphisms in the prolactin and prolactin receptor genes in risk of breast cancer. Studies of survival have suggested that high pretreatment prolactin levels were associated with treatment failure, earlier recurrence, and worse overall survival. Parity and certain medications are the only confirmed factors associated with prolactin levels in women. Overall, epidemiologic data suggest that prolactin is involved in breast cancer etiology. Further research to better elucidate these associations and their underlying mechanisms is warranted.

SSRI use and breast cancer risk by hormone receptor status

BACKGROUND

There is little evidence linking the use of selective serotonin reuptake inhibitors (SSRIs) with increased breast cancer risk, but one study has found an association with estrogen receptor negative (ER-) and progesterone receptor negative (PR-) tumors.

METHODS

We used data collected on 820 invasive breast cancer cases and 2852 hospitalized controls collected from 1990 through 2006. Information on medication use and other variables was collected by nurse interviewers. We used unconditional logistic regression analyses to evaluate the association between regular SSRI use (use at least 4 times/week for at least 3 months) and breast cancer risk overall and by subtype defined by hormone receptor status.

RESULTS

The odds ratio for all breast cancer was not elevated among regular users of SSRIs (OR = 0.89, 95% CI 0.62-1.29). None of the odds ratios varied from 1.0 in any category of hormone receptor status. Among women aged 55 and over, the odds ratios were increased for ER- (OR = 1.84, 95% CI 0.66-5.16), PR- (OR = 1.85, 95% CI 0.80-4.27), and ER-PR- (OR = 2.10, 95% CI 0.73-6.02) tumors, but these estimates were compatible with chance.

CONCLUSION

We found no association between SSRI use and breast cancer risk, overall or by hormone receptor status. Odds ratios were elevated in older women, particularly for ER- and PR- tumors, but the confidence intervals were compatible with no association.

Medication use and the risk of breast cancer

PURPOSE

To investigate whether the use of commonly-prescribed medications, primarily antihypertensives and antidepressants, is associated with an increased risk of breast cancer.

METHODS

Participants from a population-based case-control study were re-contacted 5-8 years after the original study regarding prescription and non-prescription medication use during the 10 years prior to diagnosis. Controls (n = 647) were frequency-matched to the cases (n = 600) by 5-year age groups. Medication use information was obtained during a telephone interview, and participants were sent the questionnaire in advance to facilitate recall. Odds ratios and 95% confidence intervals were estimated using conditional logistic regression.

RESULTS

A slightly increased risk of breast cancer was associated with use of calcium channel blockers (CCBs), but there was no trend with increasing duration or recency of use. Breast cancer risk was not associated with use of antidepressants, beta blockers, corticosteroids, or non-steroidal anti-inflammatory drugs. Results were similar when analyses were restricted to cases with localized disease.

CONCLUSIONS

These results support previous findings that CCBs may be associated with modest increases in breast cancer risk, but not findings that non-steroidal anti-inflammatory use reduces risk.

Review of the epidemiological literature on antidepressant use and breast cancer risk

Based on evidence that antidepressants increase levels of prolactin and may promote the growth of mammary tumor cells, there has been concern that the use of these drugs may increase the risk of breast cancer. This article reviews the epidemiological evidence on the relationship between breast cancer risk and the use of the selective serotonin reuptake inhibitors, the tricyclic antidepressants and other antidepressants. Overall, the evidence does not support the hypothesis that the use of antidepressants increases the risk of breast cancer. There is a dearth of data on long-term selective serotonin reuptake inhibitor use. Since these drugs are commonly used, it is prudent public health policy to monitor breast cancer incidence among women using this class of drug for long durations.

Use of antidepressant medications in relation to the incidence of breast cancer

Although associations have been reported between antidepressant use and risk of breast cancer, the findings have been inconsistent. We conducted a population-based case-control study among women enrolled in Group Health Cooperative (GHC), a health maintenance organization in Washington State. Women with a first primary breast cancer diagnosed between 1990 and 2001 were identified (N = 2904) and five controls were selected for each case (N = 14396). Information on antidepressant use was ascertained through the GHC pharmacy database and on breast cancer risk factors and screening mammograms from GHC records. Prior to one year before diagnosis of breast cancer, about 20% of cases and controls had used tricyclic antidepressants (adjusted odds ratio = 1.06, 95% CI 0.94-1.19) and 6% of each group had used selective serotonin reuptake inhibitors (OR = 0.98, 95% CI 0.80-1.18). There also were no differences between cases and controls with regard to the number of prescriptions filled or the timing of use. Taken as a whole, the results from this and other studies to date do not indicate an altered risk of breast cancer associated with the use of antidepressants overall, by class, or for individual antidepressants.