A prospective cohort study of oral contraceptive use and ovarian cancer among women in the United States born from 1947 to 1964

Purpose

Oral contraceptives (OCs) have been consistently associated with a reduced ovarian cancer risk; however, most previous studies included women in older birth cohorts using high-dose OC formulations. We assessed OC use, including type and dose, and ovarian cancer risk among women born between 1947 and 1964 using more recent formulations.

Methods

We included 110,929 Nurses’ Health Study II participants. Women reported duration of OC use and brands used from age 13 to baseline (1989) and every 2 years thereafter through 2009. We categorized brands by estrogen and progestin type, dose, and potency, and used Cox proportional hazards models, adjusted for age, calendar time, reproductive factors, and body mass index, to assess associations with ovarian cancer.

Results

Over 2,178,679 person-years of follow-up, we confirmed 281 cases. At baseline, 83% of participants reported ever using OCs. Compared to never use, we observed an increased risk of ovarian cancer with ≤6 months of OC use (HR 1.82; 95% CI 1.13–2.93) but a non-significant 57% (95% CI 0.18–1.03) decreased risk with ≥15 years of OC use. The increased risk among short-term users (≤1 year) was restricted to OCs containing mestranol (HR 1.83; 95% CI 1.16–2.88) and first-generation progestin (HR 1.72; 95% CI 1.11–2.65).

Conclusion

The associations between OCs and ovarian cancer observed for this younger birth cohort differ substantially from the results of previous cohort studies, possibly reflecting changes in OC formulations and use patterns over time, although these results could be due to chance. Additional studies should evaluate newer OC formulations and ovarian cancer risk.

     

Low-dose oral contraceptives: protective effect on ovarian cancer risk.

Low-dose oral contraceptive (OC) formulations containing 35 microg or less ethinyl estradiol have preferably been prescribed in the last decade, however, few data exist on its relation to ovarian cancer risk. We determined the effects of low-dose OC on the risk of ovarian cancer in a population-based case-control study, including 282 patients ages 20-75 years at diagnosis of incident primary invasive ovarian cancer or borderline tumour between 1993-1996 and 533 control subjects individually matched by age and study area to each case. Analysis excluded women who had undergone a bilateral ovariectomy or had a previous diagnosis of either ovarian cancer or borderline tumour. The association of OC use by ethinyl estradiol dose and ovarian cancer risk was assessed by odds ratios (OR), adjusting simultaneously for the other OC types and determinants of ovarian cancer risk. Ovarian cancer risk was significantly reduced by 52% for ever use of any type of OC. The reduction in risk was 7% per year of use (OR = 0.93, 95% confidence interval [CI] = 0.90-0.96) and was more evident in first-use subjects younger than 25 years. Risk reduction for ovarian cancer was substantial for use of low-dose OC, the odds ratios being 0.86 (95% CI = 0.77-0.94), 0.91 (95% CI = 0.83-1.00), and 0.95 (95% CI = 0.91-0.99) per year of using OC containing <35 microg, 35-<50 microg, and >or=50 microg ethinyl estradiol, respectively. Our study provides evidence that low-dose oral contraceptives confer substantial protection against the development of ovarian cancer.     

Oral contraceptive use and breast or ovarian cancer risk in BRCA1/2 carriers: A meta-analysis

BackgroundWomen with BRCA1 or BRCA2 mutations are at increased risk of breast and ovarian cancer. Oral contraceptives (OC) use has been associated with a reduction in ovarian cancer risk and with a moderately increased breast cancer risk, which tends to level off in the few years after stopping. The association between oral contraceptive and BRCA1 or BRCA2 gene mutations carriers is unclear.MethodsWe performed a comprehensive literature search updated to March 2010 of studies on the associations between OC users and breast or ovarian cancer for ascertained BRCA1/2 carriers. We obtained summary risk estimated for ever OC users, for duration of use and time since stopping.ResultsA total of 2855 breast cancer cases and 1503 ovarian cancer cases, carrying an ascertained BRCA1/2 mutation, were included in our meta-analyses, based on overall 18 studies. Use of OC was associated with a significant reduced risk of ovarian cancer for BRCA1/2 carriers (summary relative risk (SRR) = 0.50; 95% confidence interval (CI), 0.33–0.75). We also observed a significant 36% risk reduction for each additional 10 years of OC use (SRR: 0.64; 95% CI, 0.53–0.78; P trend < 0.01). We found no evidence of a significant association between OC and breast cancer risk in carriers (SRR: 1.13; 95% CI, 0.88–1.45) and with duration of use. OC formulations used before 1975 were associated with a significant increased risk of breast cancer (SRR: 1.47; 95% 1.06, 2.04), but no evidence of a significant association was found with use of more recent formulations (SRR: 1.17; 95% 0.74, 1.86).ConclusionsOC users carrying an ascertained BRCA1/2 mutation have a reduced risk of ovarian cancer, proportional to the duration of use. There is no evidence that recent OC formulations increase breast cancer risk in carriers.     

Oral contraceptives decrease the prevalence of ovarian cancer in the hen

Ovarian cancer is the leading cause of reproductive cancer death in U.S. women. This high mortality rate is due to the lack of early detection methods and ineffectiveness of therapy for advanced disease. Until more effective screening methods and therapies are developed, chemoprevention strategies are warranted. The hen has a high spontaneous prevalence of ovarian cancer and has been used as a model for studying ovarian cancer chemoprevention. In this study, we used the hen to determine the effect of progestin alone, estrogen alone, or progestin and estrogen in combination (as found in oral contraceptives) on ovarian cancer prevalence. We found that treatment with progestin alone and in combination with estrogen decreased the prevalence of ovarian cancer. A significant risk reduction of 91% was observed in the group treated with progestin alone (risk ratio = 0.0909; 95% CI: 0.0117-0.704) and an 81% reduction was observed in the group treated with progestin plus estrogen (risk ratio = 0.1916; 95% CI = 0.043-0.864). Egg production was also significantly reduced in these treatment groups compared with control. We found no effect of progestin, either alone or in combination with estrogen, on apoptosis or proliferation in the ovary, indicating that this is not the likely mechanism responsible for the protective effect of progestin in the hen. Our results support the use of oral contraceptives to prevent ovarian cancer and suggest that ovulation is related to the risk of ovarian cancer in hens and that other factors, such as hormones, more than likely modify this risk.     

Menopausal hormone therapy treatment options and ovarian cancer risk: A Swedish prospective population-based matched-cohort study

Although menopausal hormone therapy (MHT) seemingly increases the risk of ovarian cancer, evidence is insufficient whether the risk varies between various MHT formulations, regimens and administration modes. With the aim of filling these knowledge gaps, we investigated the effect of different MHT treatment options on the risk of ovarian cancer. This prospective Swedish population-based matched-cohort study included all women ≥40 years having used systemic MHT between 2005 and 2012 (288,950 ever-users), group-level matched (1:3) to 866,546 nonusers. MHT use was ascertained from the Swedish Prescribed Drug Registry and data was linked to several national health data registries. Multivariable conditional logistic regression provided odds ratios (ORs) and 95% confidence intervals (CIs) adjusted for parity, and comorbidities. Current EP-MHT use was associated with a modestly increased risk of ovarian cancer (OR = 1.38, 95% CI 1.18–1.62), while no consistent risk was found among past users (OR = 1.00, 95% CI 0.84–1.18). Current continuous testosterone derived (OR = 1.50, 95% CI 1.15–1.96) regimens increased the risk whereas progesterone derived (OR = 1.48, 95% CI 1.00–2.21) regimens increased the risk marginally. Nonsignificant positive associations were observed for sequential regimens (OR = 1.87, 95% CI 0.70–5.08; OR = 1.54, 95% CI 0.96–2.47, respectively). An inverse relationship was observed for all E-MHT use (OR = 0.25, 95% CI 0.22–0.29), but this association might partly be explained by underreporting of oophorectomies or tubal ligations. Current cutaneous EP-MHT (OR = 1.28, 95% CI 0.81–2.02) suggested a possibly lower risk than oral MHT (OR = 1.48, 95% CI 1.25–1.75). In conclusion EP-MHT, notably continuous regimens, were associated with a modestly increased risk of ovarian cancer. The role of E-MHT requires further clarification.     

Hormone use and risk for lung cancer: a pooled analysis from the International Lung Cancer Consortium (ILCCO)

Background:

The association between oral contraceptive (OC) use, hormone replacement therapy (HRT) and lung cancer risk in women is still debated.

Methods:

We performed a pooled analysis of six case–control studies (1961 cases and 2609 controls) contributing to the International Lung Cancer Consortium. Potential associations were investigated with multivariable unconditional logistic regression and meta-analytic models. Multinomial logistic regressions were performed to investigate lung cancer risk across histologic types.

Results:

A reduced lung cancer risk was found for OC (odds ratio (OR)=0.81; 95% confidence interval (CI): 0.68–0.97) and HRT ever users (OR=0.77; 95% CI: 0.66–0.90). Both oestrogen only and oestrogen+progestin HRT were associated with decreased risk (OR=0.76; 95% CI: 0.61–0.94, and OR=0.66; 95% CI: 0.49–0.88, respectively). No dose-response relationship was observed with years of OC/HRT use. The greatest risk reduction was seen for squamous cell carcinoma (OR=0.53; 95% CI: 0.37–0.76) in OC users and in both adenocarcinoma (OR=0.79; 95% CI: 0.66–0.95) and small cell carcinoma (OR=0.37; 95% CI: 0.19–0.71) in HRT users. No interaction with smoking status or BMI was observed.

Conclusion:

Our findings suggest that exogenous hormones can play a protective role in lung cancer aetiology. However, given inconsistencies with epidemiological evidence from cohort studies, further and larger investigations are needed for a more comprehensive view of lung cancer development in women.     

A prospective study of postmenopausal hormone use and ovarian cancer risk

The relationship between postmenopausal hormone use (PMH) and ovarian cancer risk is unclear, particularly for specific hormone formulations, but recent studies suggest that there is a positive association. We conducted a prospective observational study with 82,905 postmenopausal women, including 389 ovarian cancers, in the Nurses' Health Study from 1976 to 2002. Compared with never users of PMH, both current and past users of > or =5 years had a significantly elevated risk of ovarian cancer (RR=1.41, 95% confidence interval (CI) 1.07-1.86 and relative risk (RR)=1.52, 95% CI 1.01-2.27, respectively). Examined by hormone type in continuous years, use of unopposed estrogen was associated with a significant increase in the risk of epithelial ovarian cancer (P for trend <0.001; RR for 5-year increment of use=1.25, 95% CI 1.12-1.38). Use of estrogen plus progestin (RR for 5-year increment of use=1.04, 95% CI 0.82-1.32) was not significantly associated with ovarian cancer risk. Generally, results were similar for serous tumours (RR for 5-year increment of unopposed estrogen use=1.23, 95% CI 1.07-1.40) and slightly stronger for endometrioid tumours (RR for 5-year increment of unopposed estrogen use=1.53, 95% CI 1.20-1.94). Recency of use was not significantly associated with ovarian cancer risk, but statistical power was limited here.     

Estrogen and estrogen-progestin replacement therapy and risk of postmenopausal breast cancer in Canada

Objective: To examine the association between hormone replacement therapy (HRT) use and breast cancer incidence and to determine whether the association differs according to type of regimen. Method: Data were collected in Ontario from 404 incident cases and 403 age frequency-matched controls, between 1995 and 1996, using a self-administered questionnaire. Results: Multivariate analyses revealed an elevated odds ratio among long-term (ten years) HRT users (odds ratio (OR) = 1.80, 95% confidence interval (CI) 1.06–3.06). Risk among long-term estrogen–progestin users was substantially higher (OR = 3.48, 95% CI 1.00–12.11) than risk among long-term users of estrogen alone (OR = 1.74, 95% CI 0.93–3.24). Among both estrogen and estrogen–progestin users, positive associations were not observed for durations of use less than ten years. Conclusion: These data suggest that long-term use of HRT increases the risk of breast cancer and that estrogen–progestin therapy may be more detrimental than estrogen use alone.     

Oral contraceptive and IUD use and endometrial cancer: a population-based case-control study in Shanghai, China

Oral contraceptive (OC) and intrauterine device (IUD) use have been shown to be protective factors for endometrial cancer in several epidemiological studies; however, few studies have been conducted in Chinese populations. We evaluated the association between OC and IUD use and endometrial cancer risk in a population-based case-control study among Chinese women in Shanghai, China. The study included 1,204 newly diagnosed endometrial cancer cases and 1,212 age frequency-matched healthy controls. Logistic regression models were used to estimate adjusted odds ratios (OR) and their 95% confidence intervals (95% CI). In our study population, 18.5% cases and 24.9% controls reported having ever used OCs with an OR of 0.75 (95% CI, 0.60-0.93), after adjusting for known risk or protective factors for endometrial cancer. The risk of endometrial cancer decreased with long-term use of OCs with the OR for more than 72 months of use being 0.50 (95% CI, 0.30-0.85). The effect of OC use remained 25 or more years after cessation of use; the associated OR was 0.57 (95% CI = 0.42-0.78) as compared to nonusers. Similarly, fewer cases than controls had ever used IUD, with the multivariable adjusted OR being 0.53 (95% CI = 0.43-0.65). A reduction in risk was observed regardless the duration of use or age at first and last use. These results suggest that OC and IUD use may confer long-term protection against endometrial cancer.     

Long-term effects of oral contraceptives on ovarian cancer risk

Several epidemiologic studies have reported a protective effect of oral contraceptives (OCs) on ovarian cancer. However, there remain open issues, including better quantification of time-related factors such as time since last use, age at first use and time since first use. We performed a collaborative reanalysis of 6 case-control studies conducted between 1978 and 1999 in the United Kingdom, Greece and Italy, including a total of 2,768 incident, histologically confirmed cases of epithelial ovarian cancer and 6,274 hospital controls under age 70 years. A reduced risk of ovarian cancer was found for ever- compared to never-users [odds ratio (OR) = 0.66, 95% confidence interval (CI) 0.56-0.79], and a stronger reduction was observed for women who had used OCs for > or =5 years (OR = 0.50, 95% CI 0.33-0.76) compared to those who had used them for <5 years. The protective effect of OCs on ovarian cancer was consistent across strata of age, parity, menopausal status and family history of breast or ovarian cancer. After allowance for duration of use, no other time factor was related to ovarian cancer risk: the reduced risk was similar for women who stopped OC use > or =20 years before compared to <10 years; likewise, no significant modification of risk reduction was observed for age at first OC use and time since first OC use. The present analysis indicates that, after taking into account duration of OC use, the OC protection from ovarian cancer persists for a long time after stopping use.     

Sex hormones and the risk of keratinocyte cancers among women in the United States: A population‐based case–control study

Men are at a higher risk of developing both squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) than women, but there is emerging evidence that women may be experiencing greater increases in the incidence rates of these malignancies than men. One possible explanation is the expanding use of sex steroids among women, although only a few studies have examined this hypothesis. As part of a population‐based, case–control study of women in New Hampshire, USA, we sought to evaluate the risk of SCC, BCC, and early‐onset BCC in relation to exogenous and endogenous sex hormones. We found that oral contraceptive (OC) use was associated with an increased risk of SCC (OR = 1.4, 95% CI = 1.1–1.8) and BCC (OR = 1.4, 95% CI = 1.0‐1.8), particularly high estrogen dose (>50 mg) OC use. Hormone replacement therapy (HRT) use also related to SCC, with an elevated OR largely for progestin use (OR = 1.4, 95% CI = 1.1–1.8). Additionally, both OC use and combination HRT use were associated with more aggressive BCC subtypes. In contrast, menstrual and reproductive history did not appear to influence keratinocyte cancer risk in our data. Our findings provide evidence that use of sex steroids may enhance risk of keratinocyte cancer.     

Oral contraceptive use, reproductive factors, and colorectal cancer risk: findings from Wisconsin.

We investigated the association of oral contraceptive (OC) use and reproductive factors with colorectal cancer risk in a large population-based case-control study. Cases were women ages 20 to 74 years, living in Wisconsin, with a new diagnosis of colon (n = 1,122) or rectal (n = 366) cancer. Control participants were randomly selected from population lists of similarly aged female Wisconsin residents (n = 4,297). Risk factor information was collected through structured telephone interviews. Compared with never users, OC users had an odds ratio (OR) of 0.89 [95% confidence interval (95% CI), 0.75-1.06] for colorectal cancer. OC use associations did not differ significantly between colon and rectal cancer sites; however, when compared with never users, recent OC users (<14 years) seemed at reduced risk of rectal cancer (OR, 0.53; 95% CI, 0.28-1.00). Women with age at first birth older than the median (23 years) had 0.83 times the risk of colon cancer compared with women with age at first birth below the median (95% CI, 0.70-0.98). We observed an inverse trend between increasing parity and rectal cancer risk (P = 0.05). Compared with nulliparous women, women with five or more births had 0.66 times the risk of rectal cancer (95% CI, 0.43-1.02). Compared with postmenopausal women, premenopausal women were at reduced risk (OR, 0.67; 95% CI, 0.47-0.97) of colorectal cancer. No significant associations were observed between colorectal cancer risk and age at menarche or age at menopause. These findings suggest differential roles of reproductive factors in colon and rectal cancer etiology.     

Menopausal hormone therapy and risk of epithelial ovarian cancer.

Substantial increase in the use of menopausal hormone therapy (HT) throughout the 1990s, followed by widespread discontinuation after the 2002 publication of the Women's Health Initiative findings, has resulted in large numbers of former HT users among U.S. women. However, few studies have examined whether ovarian cancer risk varies according to recency and duration of specific HT regimens. We assessed risk of epithelial ovarian cancer among users of unopposed estrogen (ET) and combined estrogen/progestogen (EPT). In a population-based study in Washington state, 812 women with ovarian cancer diagnosed in 2002 to 2005 and 1,313 controls were interviewed in person about the use of HT and other characteristics. Women who used a single form of therapy (ET or EPT) were compared with women who never used HT using logistic regression to calculate odds ratios (OR) and 95% confidence intervals (95% CIs). Risk was increased among current or recent (within the last 3 years) users of ET with > or = 5 years of use (ORs, 95% CIs: 1.6, 1.1-2.5 and 1.8, 0.8-3.7, respectively). Little increase in risk was noted among long-term ET users who discontinued use in the more distant past (OR, 1.2; 95% CI, 0.6-2.6). No increase in risk was noted among women who used only EPT, regardless of duration. Compared with women who never used HT, current users of EPT had an OR of 1.1 (95% CI, 0.8-1.5), and risk declined with increasing time since stopping; the OR was 0.7 (95% CI, 0.4-1.0) among women who had discontinued EPT within the last 3 years and 0.5 (95% CI, 0.3-0.7) among women who stopped at an earlier point. Long-term ET may be associated with an increased ovarian cancer risk that wanes after use ceases. We did not observe an increased risk with EPT, and with increasing time after stopping, a reduction in risk became increasingly evident. The progestogen component of HT may confer a risk reduction that is masked by an opposing effect of estrogen until, among former users, estrogenic influences have diminished. These findings, if replicated, may have implications both for public health and development of chemoprevention strategies.     

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

Aggregation of cancers among families with highly penetrant genetic mutations such as hereditary nonpolyposis colorectal cancer is well‐described. However, there is a paucity of data regarding familial aggregation of hormonal cancers (cancers of the breast, endometrial, ovarian and prostate) and colorectal cancer (CRC) in the general population. We investigated the association between having a first‐degree family history of breast, endometrial, ovarian, or prostate cancer and CRC risk. Population‐based CRC cases and controls were recruited by the Ontario Familial Colorectal Cancer Registry (OFCCR). Logistic regression was conducted to obtain odds ratio (OR) estimates and 95% confidence intervals (95% CIs). First‐degree family history of breast cancer was associated with a modest, borderline statistically significant increased CRC risk (age‐, sex‐adjusted OR = 1.2, 95% CI = 1.0, 1.5). The magnitude of CRC risk was greatest if more than one first‐degree kin had breast cancer (age‐, sex‐adjusted OR = 1.7, 95% CI = 1.0, 2.0), as well as if the kin was diagnosed at >50 years of age (age‐, sex‐adjusted OR = 1.4, 95% CI = 1.1, 1.8). Family history of ovarian cancer was associated with reduced CRC risk (multivariate‐adjusted OR = 0.6, 95% CI = 0.3, 1.0). Although statistically significant increases in CRC risk were observed in the age‐, sex‐adjusted OR estimates for family history of endometrial and prostate cancers, the associations were no longer significant after multivariate‐adjustment. In conclusion, individuals with a first‐degree kin with breast cancer may have a modest increased risk for CRC compared to individuals without. © 2009 UICC     

A splicing variant of TERT identified by GWAS interacts with menopausal estrogen therapy in risk of ovarian cancer

Menopausal estrogen‐alone therapy (ET) is a well‐established risk factor for serous and endometrioid ovarian cancer. Genetics also plays a role in ovarian cancer, which is partly attributable to 18 confirmed ovarian cancer susceptibility loci identified by genome‐wide association studies. The interplay among these loci, ET use and ovarian cancer risk has yet to be evaluated. We analyzed data from 1,414 serous cases, 337 endometrioid cases and 4,051 controls across 10 case–control studies participating in the Ovarian Cancer Association Consortium (OCAC). Conditional logistic regression was used to determine the association between the confirmed susceptibility variants and risk of serous and endometrioid ovarian cancer among ET users and non‐users separately and to test for statistical interaction. A splicing variant in TERT, rs10069690, showed a statistically significant interaction with ET use for risk of serous ovarian cancer (p_int = 0.013). ET users carrying the T allele had a 51% increased risk of disease (OR = 1.51, 95% CI 1.19–1.91), which was stronger for long‐term ET users of 10+ years (OR = 1.85, 95% CI 1.28–2.66, p_int = 0.034). Non‐users showed essentially no association (OR = 1.08, 95% CI 0.96–1.21). Two additional genomic regions harboring rs7207826 (C allele) and rs56318008 (T allele) also had significant interactions with ET use for the endometrioid histotype (p_int = 0.021 and p_int = 0.037, respectively). Hence, three confirmed susceptibility variants were identified whose associations with ovarian cancer risk are modified by ET exposure; follow‐up is warranted given that these interactions are not adjusted for multiple comparisons. These findings, if validated, may elucidate the mechanism of action of these loci.     

Family history of cancer and risk of ovarian cancer

The aim of this study was to examine the relationship between history of cancer in first-degree relatives and ovarian cancer risk. Between 1992 and 1999, we conducted a case-control study in Italy on 1031 women with epithelial ovarian cancer and 2411 women admitted to hospital for acute non-neoplastic conditions. Odds ratios (OR) were estimated using unconditional logistic regression, adjusted for age and several potential confounders. Overall, 27 cases and nine controls reported a family history of ovarian cancer (OR = 7.0; 95% confidence interval (CI) 3.1-16). The OR was 23 (95% CI 2.6-212) below age 50 years, based on 10 cases and one control only. The risk of ovarian cancer was also increased in women with a family history of cancer of the stomach (OR = 1.5; 95% CI 1.0-2.1), intestine (OR = 1.7; 95% CI 1.2-2.4), lung (OR = 1.3; 95% CI 1.0-1.8), breast (OR = 2.3; 95% CI 1.7-3.1), lymphomas (OR = 2.3; 95% CI 1.0-5.1) and all sites (OR = 1.6; 95% CI 1.4-1.9). Our results confirm the higher ovarian cancer risk in women with a family history of ovarian and breast cancer, and suggest a few associations with other sites.     

Regular use of analgesic drugs and ovarian cancer risk.

Analgesics have been shown to reduce risk for colorectal cancer. Results from three recent reports (D. W. Cramer et al., Lancet, 351: 104-107, 1998; C. Rodriguez et. al., Lancet, 352: 1354-1355, 1998; L. Rosenberg et al., Cancer Epidemiol. Biomark. Prev., 9: 933-937, 2000) suggest that these drugs might be associated with decreased risk for ovarian cancer. In this hospital-based case-control study, we compared 547 patients with ovarian cancer to 1094 age-matched patients with nonneoplastic conditions. All of the participants received treatment at the Roswell Park Cancer Institute between 1982 and 1998 and completed a comprehensive epidemiological questionnaire that included information on demographics, life-style factors, and reproductive characteristics as well as frequency and duration of aspirin and acetaminophen use. Women who reported that they had used one or more of these agents at least once a week for at least 6 months were classified as analgesic users. Logistic regression was used to compute crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs). Aspirin users were not at reduced risk of ovarian cancer compared with nonusers (adjusted OR, 1.00; CI, 0.73-1.39). There was also no evidence of a decrease in risk as a function of greater frequency of use or prolonged duration of use. Regular acetaminophen use was associated with a reduced risk (adjusted OR, 0.56; 95% CI, 0.34-0.86), and risk reductions were observed for women with the greatest frequency of use (adjusted OR, 0.32; 95% CI, 0.09-1.08) and longest duration of use (adjusted OR, 0.51; 95% CI, 0.27-0.97). These data suggest that regular use of acetaminophen, but not aspirin, may be associated with lower risk of ovarian cancer.     

Oral contraceptive use and mammographic patterns.

High-risk mammographic patterns represent an increased risk of contracting breast cancer and may be used as a surrogate endpoint for the disease. We examined the relationship between oral contraceptive (OC) use and mammographic patterns among 3218 Norwegian women, aged 40-56 years. Information on ever OC use, duration, and age of first OC use and other epidemiological data were obtained through questionnaires. The mammograms were categorized into five groups. Patterns I-III were combined into a low-risk group and patterns IV and V into a high-risk group. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression and adjusted for age, menopausal status, parity, age at first birth, and body mass index. Women who reported ever having used OCs were 20% more likely (OR 1.27, 95% CI 1.0-1.6) to have high-risk mammographic patterns compared with those reporting never having used OCs. There was no dose response between different measures of OC use and high-risk patterns. Among nulliparous women, ever OC users were four times more likely (OR 4.65, 95% CI 2.1-10.3) to have high-risk patterns compared with never users. Our findings suggest that, especially among nulliparous women, ever OC use may exert its effect on breast cancer risk through changes in breast tissue, which can be observed on a mammogram.     

Inverse association of NSAID use and ovarian cancer in relation to oral contraceptive use and parity

We examined the association between non-steroidal anti-inflammatory drug (NSAID) use and ovarian cancer by potential effect modifiers, parity and oral contraceptive use, in a population-based case-control study conducted in Wisconsin and Massachusetts. Women reported prior use of NSAIDs and information on risk factors in a telephone interview. A total of 487 invasive ovarian cancer cases and 2653 control women aged 20-74 years were included in the analysis. After adjustment for age, state of residence and other covariates, ever use of NSAIDs was inversely associated with ovarian cancer in never users of oral contraceptives (odds ratio (OR)=0.58, 95% confidence interval (CI) 0.42-0.80) but not for ever users (OR=0.98, 95% CI 0.71-1.35) (P-interaction=0.03). A reduced risk with NSAID use was also noted in nulliparous women (OR=0.47, 95% CI 0.27-0.82) but not among parous women (OR=0.81, 95% CI 0.64-1.04) (P-interaction=0.05). These results suggest that use of NSAIDs were beneficial to women at greatest risk for ovarian cancer.     

Estrogen plus progestin use, microsatellite instability, and the risk of colorectal cancer in women

Current users of postmenopausal hormones (PMH) have approximately 30% to 40% lower risk of colorectal cancer (CRC), although associations with specific types of hormones have been inconsistent. Further, it is not clear whether some tumor types have a different risk. We conducted a case-control study to examine the relationship between PMH and CRC. Cases (n = 1,004), ages 50 to 74 years, were identified from the Surveillance Epidemiology and End Results registry in Washington from 1998 to 2002; controls (n = 1,062) were randomly selected from population lists. Case tissue samples were obtained for microsatellite instability (MSI) analyses. Interviews collected risk-factor data for CRC, including detailed information on PMH. Multivariable logistic regression models estimated odds ratios (OR) and 95% confidence intervals (95% CI). Current use of any PMH was associated with a 20% reduction in CRC risk (95% CI 0.6-0.9). This reduction in risk was limited to women who had taken estrogen plus progestin (EP) preparations only (OR = 0.6, 95% CI 0.5-0.9); there was no association with estrogen-only (E alone) use (OR = 0.9, 95% CI 0.7-1.1). For women with MSI-low or MSI-stable tumors, there was a statistically significant 40% reduction in CRC risk associated with EP use (95% CI 0.4-0.9); there was no clear association with MSI-high tumors. EP use was associated with a decreased risk of CRC; however, there seemed to be no association with E alone data that are consistent with the recent Women's Health Initiative findings. Progestin may enhance the estrogenic effect of conjugated estrogen so the combination may be more biologically active in the colon than E alone.