Parity, age at first birth and the risk of carcinoma in situ of the breast

DCIS and LCIS: Are the Risk Factors for Developing In Situ Breast Cancer Different?

Ductal carcinoma in situ (DCIS) is widely accepted as a precursor of invasive ductal carcinoma (IDC). Lobular carcinoma in situ (LCIS) is considered a risk factor for invasive lobular carcinoma (ILC), and it is unclear whether LCIS is also a precursor. Therefore, it would be expected that similar risk factors predispose to both DCIS and IDC, but not necessarily LCIS and ILC. This study examined associations with risk factors using data from 3075 DCIS cases, 338 LCIS cases, and 1584 controls aged 35-60, recruited from the UK-based GLACIER and ICICLE case-control studies between 2007 and 2012. Analysis showed that breastfeeding in parous women was protective against DCIS and LCIS, which is consistent with research on invasive breast cancer (IBC). Additionally, long-term use of HRT in post-menopausal women increased the risk of DCIS and LCIS, with a stronger association in LCIS, similar to the association with ILC. Contrary to findings with IBC, parity and the number of births were not protective against DCIS or LCIS, while oral contraceptives showed an unexpected protective effect. These findings suggest both similarities and differences in risk factors for DCIS and LCIS compared to IBC and that there may be justification for increased breast surveillance in post-menopausal women taking long-term HRT.

Risk factors for estrogen receptor positive ductal carcinoma in situ of the breast in African American women

Background

Compared to U.S. white women, African American women are more likely to die from ductal carcinoma in situ (DCIS). Elucidation of risk factors for DCIS in African American women may provide opportunities for risk reduction.

Methods

We used data from three epidemiologic studies in the African American Breast Cancer Epidemiology and Risk Consortium to study risk factors for estrogen receptor (ER) positive DCIS (488 cases; 13,830 controls). Results were compared to associations observed for ER+ invasive breast cancer (n = 2,099).

Results

First degree family history of breast cancer was associated with increased risk of ER+ DCIS [odds ratio (OR): 1.69, 95% confidence interval (CI): 1.31, 2.17]. Oral contraceptive use within the past 10 years (vs. never) was also associated with increased risk (OR: 1.43, 95%CI: 1.03, 1.97), as was late age at first birth (≥25 years vs. <20 years) (OR: 1.26, 95%CI: 0.96, 1.67). Risk was reduced in women with older age at menarche (≥15 years vs. <11 years) (OR: 0.62, 95%CI: 0.42, 0.93) and higher body mass index (BMI) in early adulthood (≥25 vs. <20 kg/m² at age 18 or 21) (OR: 0.75, 95%CI: 0.55, 1.01). There was a positive association of recent BMI with risk in postmenopausal women only. In general, associations of risk factors for ER+ DCIS were similar in magnitude and direction to those for invasive ER+ breast cancer.

Conclusions

Our findings suggest that most risk factors for invasive ER+ breast cancer are also associated with increased risk of ER+ DCIS among African American women.

•

Few studies of risk factors for ductal carcinoma in situ (DCIS) have evaluated associations for African American women.

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We analyzed data from the African American African American Breast Cancer Epidemiology and Risk (AMBER) Consortium.

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Family history of breast cancer, reproductive factors, and anthropometric factors were associated with risk of ER+ DCIS.

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In general, risk factor associations for ER+ DCIS were similar to those for ER+ invasive breast cancer.

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Our findings support a common etiology and pathogenesis between ER+ DICS and ER+ invasive cancer in African American women.

Reproductive and menopausal factors and risk of second primary breast cancer after in situ breast carcinoma

PURPOSE

In situ breast cancer patients have a higher risk of developing a second primary breast cancer than women in the general population have of developing breast cancer. We have limited understanding of why some women with a previous in situ breast cancer develop second primary breast cancers while others do not.

METHODS

In this population-based nested case-control study, we evaluated the association between reproductive and menopausal factors and risk of developing a second primary breast cancer among women with a previous in situ breast cancer. Using conditional logistic regression, these associations were evaluated in 552 cases and 1032 individually matched controls.

RESULTS

Older age at menarche was associated with risk of second primary breast cancer among women with a previous in situ breast cancer (compared to age < 12, age 13: OR 0.60 (0.42, 0.85); age ≥ 14: OR 0.69 (0.47, 1.00); P_trend = 0.07). Breastfeeding for > 12 months was associated with a decreased risk of developing a second primary breast cancer (OR 0.62 (0.39, 0.98)). No associations were observed for other reproductive or menopausal factors evaluated.

CONCLUSIONS

Results from this study suggest that reproductive factors may play a role in development of a second primary breast cancer after diagnosis of in situ breast carcinoma.

Ductal Carcinoma In Situ

Ductal carcinoma in situ has been stable in incidence for a decade and has an excellent prognosis. Breast conservation therapy is safe and effective for most patients. Adjuvant whole breast radiation therapy is recommended to reduce the risk of local recurrence. Accelerated partial breast irradiation is a promising alternative to decrease toxicity and improve cosmetic results. Adjuvant hormonal therapy can reduce local recurrence, but should be used cautiously. Future directions in management include developing predictive tools for guidance for use of adjuvant therapy and selecting low-risk patients with ductal carcinoma in situ in whom surgery may be safely omitted.

Comparison of the association of mammographic density and clinical factors with ductal carcinoma in situ versus invasive ductal breast cancer in Korean women

BACKGROUND

In spite of the increasing incidence of in situ breast cancer, the information about the risk factors of in situ breast cancer (DCIS) is scarce as compared to the information available for invasive ductal breast cancer (IDC), with inconsistent findings regarding the difference in risk factors between DCIS and IDC.

METHODS

We enrolled 472 women with IDC and 90 women with DCIS and 1088 controls matching for age and menopausal status. Information on risk factors was collected through self-administered questionnaire. Percent mammographic dense area (PDA), absolute mammographic dense area (ADA), and nondense area were assessed using a computer-assisted thresholding technique. Odds ratio (OR) and 95% confidence intervals (CI) were estimated by conditional logistic regression model with adjustment for covariates.

RESULTS

Later age at menarche and regular physical exercise were associated with decreased risk of IDC, whereas alcohol consumption, previous benign breast disease, and family history of breast cancer were associated with increased risk of IDC. For DCIS, previous benign breast disease and alcohol consumption were associated with the increased risk, and regular physical exercise was associated with decreased risk. Increase of ADA by 1-quartile level and PDA increase by 10% were associated with 1.10 (95% CI: 1.01, 1.21) and 1.10 (95% CI: 1.01, 1.19) times greater risk of IDC, respectively. The increase of ADA by 1-quartile level and PDA increase by 10% were associated with 1.17 (95% CI: 0.91, 1.50) times and 1.11 (95% CI:0.90,1.37) times greater risk of DCIS, respectively, but the associations were not statistically significant. There was no significant difference in the association with risk factors and mammographic density measures between IDC and DCIS (P > 0.1).

CONCLUSIONS

Differential associations of DCIS with mammographic density and risk factors as compared with the associations of IDC were not evident. This finding suggests that IDC and DCIS develop through the shared causal pathways.

Pregnancy and Breast Cancer

Breast cancer is the most commonly diagnosed type of cancer among women worldwide. The majority of breast cancers are sporadic and the etiology is not well understood. Several factors have been attributed to altering the risk of breast cancer. A full-term pregnancy is a crucial factor in altering the risk. Early full-term pregnancy has been shown to reduce the lifetime risk of breast cancer, while a later first full-term pregnancy increases breast cancer risk. Epidemiological and experimental data demonstrate that spontaneous or induced abortions do not significantly alter the risk of breast cancer. In this study, we briefly discuss the different types and stages of breast cancer, various risk factors, and potential mechanisms involved in early full-term pregnancy-induced protection against breast cancer. Understanding how early full-term pregnancy induces protection against breast cancer will help design innovative preventive and therapeutic strategies. This understanding can also help in the development of molecular biomarkers that can be of tremendous help in predicting the risk of breast cancer in the general population.

Risk factors for young-onset invasive and in situ breast cancer

PURPOSE

Young-onset breast cancers tend to be more aggressive than later-onset tumors and may have different risk factor profiles. Among young-onset cases, there may also be etiologic differences between ductal carcinomas in situ (DCIS) and invasive breast cancer, particularly if some factors promote malignant transformation.

METHODS

We evaluated the association between several potential risk factors and young-onset breast cancer in the Two Sister Study (2008-2010), a sister-matched case-control study involving 1,406 women diagnosed with breast cancer before age 50 (1,185 invasive, 221 DCIS) and 1,648 controls.

RESULTS

Older age at menarche, younger age at menopause, premenopausal hysterectomy, early age at first-term pregnancy, obesity, and consumption of alcohol were associated with reduced risk of young-onset breast cancer. These patterns remained when we limited analysis to invasive breast cancers. In general, effect estimates were similar for young-onset invasive breast cancer and DCIS, although the number of DCIS cases was small.

CONCLUSIONS

In this sister-matched case-control study of young-onset breast cancer, many of the studied risk factors were associated with young-onset invasive breast cancer. There were few discernable differences in risk factors for young-onset DCIS versus young-onset invasive breast cancer.

How many etiological subtypes of breast cancer: two, three, four, or more?

Breast cancer is a heterogeneous disease, divisible into a variable number of clinical subtypes. A fundamental question is how many etiological classes underlie the clinical spectrum of breast cancer? An etiological subtype reflects a grouping with a common set of causes, whereas a clinical subtype represents a grouping with similar prognosis and/or prediction. Herein, we review the evidence for breast cancer etiological heterogeneity. We then evaluate the etiological evidence with mRNA profiling data. A bimodal age distribution at diagnosis with peak frequencies near ages 50 and 70 years is a fundamental characteristic of breast cancer for important tumor features, clinical characteristics, risk factor profiles, and molecular subtypes. The bimodal peak frequencies at diagnosis divide breast cancer overall into a "mixture" of two main components in varying proportions in different cancer populations. The first breast cancer tends to arise early in life with modal age-at-diagnosis near 50 years and generally behaves aggressively. The second breast cancer occurs later in life with modal age near 70 years and usually portends a more indolent clinical course. These epidemiological and molecular data are consistent with a two-component mixture model and compatible with a hierarchal view of breast cancers arising from two main cell types of origin. Notwithstanding the potential added value of more detailed categorizations for personalized breast cancer treatment, we suggest that the development of better criteria to identify the two proposed etiologic classes would advance breast cancer research and prevention.

In situ breast cancer and microchimerism

Microchimeric cells of fetal origin persistent in the maternal circulation post-partum are associated with protection against invasive breast cancer. Here using quantitative genomic methods, we evaluated for the presence of male fetal microchimerism in buffy coat cells from women with a prior history of breast carcinomas in situ (CIS) and in healthy controls. Fetal microchimerism was detected in 75 of 88 controls (85%) and in 57 of 89 CIS patients (64%). The odds ratio for protection against non-invasive breast disease was 0.26 (95% confidence interval 0.12-0.56; p < 0.001 adjusted for age and body mass index). Similar to women with invasive breast cancer, women with CIS who are naturally at high risk for future invasive disease were deficient for fetal microchimerism. In addition to autologous anti-tumor immune responses, the maintenance of haploidentical microchimerism may impart an allogeneic edge in immunosurveillance.

Do reproductive factors influence T, N, and M classes of ductal and lobular breast cancers? A nation-wide follow-up study

BACKGROUNDS

The clinical tumor-node-metastasis (T, N and M) classes of breast cancers provide important prognostic information. However, the possible association of TNM classes with reproductive factors has remained largely unexplored. Because every woman has a reproductive history, implications to outcome prediction are potentially significant.

METHODS

During the study period from 2002 through 2008, 5,614 pre- and 27,310 postmenopausal patients were identified in the Swedish Family-Cancer Database. Ordinal logistic regression analysis was used to estimate odds ratios (ORs) for TNM classes of breast cancers by histology. The reproductive variables were parity, age at first and last childbirth and time interval between first and last childbirth.

RESULTS

Among postmenopausal patients, the ORs for high-T class (T2-T4) (tumor size ≥2 cm) and metastasis were decreased by parity. A late age at first and last childbirth associated with high-T class and the effects were higher for lobular (OR for late age at first childbirth  = 2.85) than ductal carcinoma. Overall, long time interval between first and last childbirth was related to high-T class and metastasis. However, a short time interval between first and last childbirth in patients with late age at first or last childbirth increased the risk of metastasis. Late age at last childbirth was associated with increased occurrence of lobular carcinoma in situ. Among premenopausal ductal carcinoma patients, nulliparity and early age at first childbirth were associated with high-T class.

CONCLUSIONS

Increasing parity was protective against high-T class and metastasis; late ages at first and last childbirth were risk factors for high-T class in postmenopausal breast cancers. The current decline in parity and delayed age at first childbirth in many countries may negatively influence prognosis of breast cancer.

Reproductive and menstrual factors and risk of ductal carcinoma in situ of the breast in a cohort of postmenopausal women

PURPOSE

The contribution of menstrual and reproductive factors to risk of ductal carcinoma (DCIS) of the breast is poorly understood.

METHODS

The association between menstrual and reproductive factors and subsequent DCIS risk was examined in Women's Health Initiative (WHI) clinical trial participants, in which mammography was protocol mandated. The cohort consisted of 64,060 women, among whom 664 cases of DCIS were ascertained over a median follow-up of 12.0 years. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI).

RESULTS

After adjustment for covariates, only older age at menopause (HR ≥ 55 vs. 45-54 : 1.39, 95% CI 1.08-1.79) was significantly associated with risk; however, greater parity (HR ≥ 5 live births vs. 0: 0.70, 95% CI 0.47-1.03), among parous women, and age at first live birth (HR ≥ 30 years relative to <20 years: 1.32, 95% CI 0.92-1.90) were of borderline significance. Age at menarche and months of breast-feeding were not associated with risk. Associations did not differ between high- and low-/moderate-grade DCIS, or by level of body mass index or family history of breast cancer; however, there was a suggestion that the associations of age at menopause, parity, and age at first live birth were limited to women who had ever used hormone therapy.

CONCLUSIONS

Findings from this large cohort of postmenopausal women suggest that age at menopause, and possibly, age at first live birth, and parity are associated with risk of DCIS, whereas age at menarche and duration of breast-feeding are not.

Reproductive and hormonal risk factors for ductal carcinoma in situ of the breast

One-fifth of all newly diagnosed breast cancer cases are ductal carcinoma in situ (DCIS), but little is known about DCIS risk factors. Recent studies suggest that some subtypes of DCIS (high grade or comedo) share histopathologic and epidemiologic characteristics with invasive disease, whereas others (medium or low grade or non-comedo) show different patterns. To investigate whether reproductive and hormonal risk factors differ among comedo and non-comedo types of DCIS and invasive breast cancer (IBC), we used a population-based case-control study of 1,808 invasive and 446 DCIS breast cancer cases and their age and race frequency-matched controls (1,564 invasive and 458 DCIS). Three or more full-term pregnancies showed a strong inverse association with comedo-type DCIS [odds ratio (OR), 0.53; 95% confidence interval (95% CI), 0.30-0.95] and a weaker inverse association for non-comedo DCIS (OR, 0.73; 95% CI, 0.42-1.27). Several risk factors (age at first full-term pregnancy, breast-feeding, and age at menopause) showed similar associations for comedo-type DCIS and IBC but different associations for non-comedo DCIS. Ten or more years of oral contraceptive showed a positive association with comedo-type DCIS (OR, 1.31; 95% CI, 0.70-2.47) and IBC (OR, 2.33; 95% CI, 1.06-5.09) but an inverse association for non-comedo DCIS (OR, 0.51; 95% CI, 0.25-1.04). Our results support the theory that comedo-type DCIS may share hormonal and reproductive risk factors with IBC, whereas the etiology of non-comedo DCIS deserves further investigation.

Widowhood, family size, and post-reproductive mortality: a comparative analysis of three populations in nineteenth-century Europe

Researchers from a number of disciplines have offered competing theories about the effects oJ childbearing on parents 'postreproductive longevity. The "disposable soma theory" argues that investments in somatic maintenance increase longevity but reduce childbearing. "Maternal depletion" models suggest that the rigors of childrearing increase mortality in later years. Other researchers consider continued childbearing a sign of healthy aging and a predictor of future longevity. Empirical studies have produced inconsistent and contradictory results. Our focus is on the experience of widowhood, which has been ignored in previous studies. We hypothesize that the death of a spouse is a stressful event with long-term consequences for health, especially for women with small children. Data are drawn from historical sources in Sweden, Belgium, and the Netherlands from 1766 to 1980. Postreproductive mortality was highest among young widows with larger families in all three samples. Age at last birth had little or no effect. We conclude that raising children under adverse circumstances can have long-lasting, harmful effects on a mother's health.

Breast density in relation to risk of ductal carcinoma in situ of the breast in women undergoing screening mammography

OBJECTIVE

To examine the association between breast density and risk of breast ductal carcinoma in situ (DCIS).

METHODS

We assessed breast density in relation to DCIS risk using combined data from statewide mammography registries in NH and VT. The prospective analyses were based on 572 DCIS cases arising in 154,936 women (58,496 premenopausal and 96,440 postmenopausal). Women in the study were followed on average 4.1 years. Breast density was scored by community radiologists using BIRADS categories (fatty, scattered density, heterogeneous density, extreme density).

RESULTS

In premenopausal women, based on 157 cases, the RR for DCIS risk were 0.29 (95% CI: 0.0.04, 2.24) for fatty breasts, 2.06 (95% CI: 1.39, 3.05) for heterogeneous density, and 2.40 (95% CI: 1.47, 3.91) for extreme density, relative to scattered density. In postmenopausal women, based on 369 cases, the RR for DCIS risk were 0.58 (95% CI: 0.37, 0.93) for fatty breasts, 1.41 (95% CI: 1.12, 1.78) for heterogeneous density, and 1.49 (95% CI: 0.93, 2.37) for extreme density, relative to scattered density. The possible interaction between breast density and menopausal status in relation to DCIS risk was not statistically significant.

CONCLUSIONS

We observed an association between breast density and DCIS risk. Although the association seemed stronger in premenopausal women, there was no evidence of an interaction involving breast density and menopausal status.

“Population Lab”: The Creation of Virtual Populations for Genetic Epidemiology Research

BACKGROUND

Studies of familial aggregation of disease routinely use linked population registers to construct retrospective cohorts. Although such resources have provided numerous estimates of familial risk, little is known regarding the sensitivity of the estimates to assumed disease models, changing demographics and incidence, and incompleteness of the data. Furthermore, there are no standard tools for testing the validity of estimates from standard epidemiologic designs and from new analytic strategies using register data.

METHODS

We present a method and a software package for simulating realistic populations of related individuals, using easily available vital statistics (population counts and fertility and mortality rates). The virtual population is stored in a pedigree file, allowing for easy retrieval of relatives and family structures. We simulate breast cancer in our population using age-specific incidence rates.

RESULTS

The Swedish population is simulated as dynamically evolving over the calendar period 1955-2002. The simulated and real population agree well on important features such as age profile, sibship size distribution, and average age at first birth. Using breast cancer as an example, we present several models of familial disease aggregation and show that the parameters used in the simulations are faithfully estimated. In addition, we illustrate how our simulated population provides insight into how incomplete family history in real register data can affect estimates of familial risk.

CONCLUSIONS

This simulation method can be used to investigate various underlying models of disease aggregation in families and enhance the development of optimal approaches for family studies. The software package, Population Lab, is available for free download (http://www.meb.ki.se/ approximately marrei/software/poplab/ and http://cran.at.r-project.org/).

The association of mammographic density with ductal carcinoma in situ of the breast: the Multiethnic Cohort

Introduction

It is well established that women with high mammographic density are at greater risk for breast cancer than are women with low breast density. However, little research has been done on mammographic density and ductal carcinoma in situ (DCIS) of the breast, which is thought to be a precursor lesion to some invasive breast cancers.

Method

We conducted a nested case-control study within the Multiethnic Cohort, and compared the mammographic densities of 482 patients with invasive breast cancer and 119 with breast DCIS cases versus those of 667 cancer-free control subjects. A reader blinded to disease status performed computer-assisted density assessment. For women with more than one mammogram, mean density values were computed. Polytomous logistic regression models were used to compute adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for two measurements of mammographic density: percentage density and dense area.

Results

Mammographic density was associated with invasive breast cancer and breast DCIS. For the highest category of percentage breast density (≥50%) as compared with the lowest (<10%), the OR was 3.58 (95% CI 2.26–5.66) for invasive breast cancer and 2.86 (1.38–5.94) for breast DCIS. Similarly, for the highest category of dense area (≥45 cm²) as compared with the lowest (<15 cm²), the OR was 2.92 (95% CI 2.01–4.25) for invasive breast cancer and 2.59 (1.39–4.82) for breast DCIS. Trend tests were significant for invasive breast cancer (P for trend < 0.0001) and breast DCIS (P for trend < 0.001) for both percentage density and dense area.

Conclusion

The similar strength of association for mammographic density with breast DCIS and invasive breast cancer supports the hypothesis that both diseases may have a common etiology.

The natural history of ductal carcinoma in situ of the breast: a review

BACKGROUND

Ductal carcinoma in situ represents about 20% of all tumours diagnosed within mammographic screening programs. The natural history of DCIS is poorly understood, as it cannot be observed directly. Estimates of the proportion of DCIS that progress to invasive cancer, as well as factors that may influence progression, are important for clinical management. Here we review various sources of evidence regarding the natural history of DCIS.

METHODS

We identified relevant publications of studies on: follow-up studies of DCIS initially misdiagnosed as benign, studies of recurrence of DCIS as invasive cancer, autopsy studies, studies of risk factors for DCIS, animal studies and studies that used mathematical models to study growth of DCIS and invasive cancer. Data sources included the MEDLINE data base, searches of articles cited in key reviews and editorials.

RESULTS

The most direct evidence regarding the progression of DCIS to invasive cancer comes from studies where DCIS was initially misdiagnosed as benign and treated by biopsy alone. These studies suggest that between 14-53% of DCIS may progress to invasive cancer over a period of 10 or more years. The reported prevalence of undiagnosed DCIS in autopsy studies, of approximately 9%, has been used to suggest a larger reservoir of DCIS may exist in the population. All types of study designs reviewed had limitations that may bias the estimate of progression in either direction.

CONCLUSION

The available evidence suggests not all DCIS will progress to invasive cancer in the medium term but precise estimates of progression are not possible given the limitations of the data. Mathematical modelling of various scenarios of progression and studies of genetic factors involved in progression may shed further light on the natural history of DCIS.

Haploinsufficiency for BRCA1 is associated with normal levels of DNA nucleotide excision repair in breast tissue and blood lymphocytes

Background

Screening mammography has had a positive impact on breast cancer mortality but cannot detect all breast tumors. In a small study, we confirmed that low power magnetic resonance imaging (MRI) could identify mammographically undetectable tumors by applying it to a high risk population. Tumors detected by this new technology could have unique etiologies and/or presentations, and may represent an increasing proportion of clinical practice as new screening methods are validated and applied. A very important aspect of this etiology is genomic instability, which is associated with the loss of activity of the breast cancer-predisposing genes BRCA1 and BRCA2. In sporadic breast cancer, however, there is evidence for the involvement of a different pathway of DNA repair, nucleotide excision repair (NER), which remediates lesions that cause a distortion of the DNA helix, including DNA cross-links.

Case presentation

We describe a breast cancer patient with a mammographically undetectable stage I tumor identified in our MRI screening study. She was originally considered to be at high risk due to the familial occurrence of breast and other types of cancer, and after diagnosis was confirmed as a carrier of a Q1200X mutation in the BRCA1 gene. In vitro analysis of her normal breast tissue showed no differences in growth rate or differentiation potential from disease-free controls. Analysis of cultured blood lymphocyte and breast epithelial cell samples with the unscheduled DNA synthesis (UDS) assay revealed no deficiency in NER.

Conclusion

As new breast cancer screening methods become available and cost effective, patients such as this one will constitute an increasing proportion of the incident population, so it is important to determine whether they differ from current patients in any clinically important ways. Despite her status as a BRCA1 mutation carrier, and her mammographically dense breast tissue, we did not find increased cell proliferation or deficient differentiation potential in breast epithelial cells from this patient which might have contributed to her cancer susceptibility. Although NER deficiency has been demonstrated repeatedly in blood samples from sporadic breast cancer patients, analysis of blood cultured lymphocytes and breast epithelial cells for this patient proves definitively that heterozygosity for inactivation of BRCA1 does not intrinsically confer this type of genetic instability. These data suggest that the mechanism of genomic instability driving the carcinogenic process may be fundamentally different in hereditary and sporadic breast cancer, resulting in different genotoxic susceptibilities, oncogene mutations, and a different molecular pathogenesis.

Long-term effects of childbearing on mortality: evidence from pre-industrial Sweden

This paper presents an analysis of the impact of childbearing history on later-life mortality for ever-married men and women using historical micro-level data of high quality for southern Sweden. The analysis uses a Cox proportional hazards model, estimating the effects on old-age mortality of number of births and timing of first and last births. By studying the effects of previous childbearing on mortality by sex and social status, we also gain important insights into the mechanisms relating childbearing to mortality in old age. The results show that number of children ever born had a statistically significant negative impact on longevity after age 50 for females but not for males. Analysis by social group shows that only landless women experienced higher mortality from having more children, which seems to indicate that the main explanations are to be found in social or economic conditions specific to females, rather than in the strictly biological or physiological effects of childbearing.

Sexual Orientation, Health Risk Factors, and Physical Functioning in the Nurses' Health Study II

OBJECTIVES

To examine associations between sexual orientation and breast cancer risk factors, cardiovascular disease (CVD) risk factors, mental health status, and health-related functioning.

METHODS

We compared participants in the Nurses' Health Study II (NHSII) reporting a lesbian or bisexual orientation with those reporting a heterosexual orientation, with heterosexuals serving as the reference group for all comparisons. Prevalence of health behaviors and conditions was adjusted for differences in the distribution of age, ancestry, and region of residence by standardizing to the distribution of the overall cohort. Multivariate prevalence ratios were calculated to compare lesbians and bisexuals with heterosexuals using binomial regression with the log link function. Means of health conditions were measured using continuous scales standardized to the distribution of the overall cohort. Differences in means comparing lesbians and bisexuals with heterosexuals were tested by multivariate linear regression. All comparisons were adjusted for age, ancestry, and region of residence.

RESULTS

Based on information from 90,823 women aged 32-51 in 1995, those reporting a sexual orientation of lesbian (n = 694) had a higher prevalence of risk factors for breast cancer, including nulliparity and high daily alcohol intake, compared with heterosexual women. Lesbians also had a higher prevalence of several risk factors for CVD, including higher body mass index (BMI) and elevated prevalence of current smoking. Lesbians were more likely to report depression and the use of antidepressants. Key results for health risk factors were similar for lesbians and bisexual women (n = 317).

CONCLUSIONS

Lesbian and bisexual women were found to have a higher prevalence of several important risk factors for breast cancer, CVD, and poor mental health and functioning outcomes. Most of these risk factors are modifiable, and appropriate interventions could play an important role in improving the health status of lesbian and bisexual women.

Ductal carcinoma in situ, complexities and challenges

The incidence of ductal carcinoma in situ (DCIS), a noninvasive form of breast cancer, has increased markedly in recent decades, and DCIS now accounts for approximately 20% of breast cancers diagnosed by mammography. Laboratory and patient data suggest that DCIS is a precursor lesion for invasive cancer. The appropriate classification of DCIS has provoked much debate; a number of classification systems have been developed, but there is a lack of uniformity in the diagnosis and prognostication of this disease. Further investigation of molecular markers should improve the classification of DCIS and our understanding of its relationship to invasive disease. Controversy also exists with regard to the optimal management of DCIS patients. In the past, mastectomy was the primary treatment for patients with DCIS, but as with invasive cancer, breast-conserving surgery has become the standard approach. Three randomized trials have reported a statistically significant decrease in the risk of recurrence with radiation therapy in combination with lumpectomy compared with lumpectomy alone, but there was no survival advantage with the addition of radiotherapy. Two randomized trials have suggested an additional benefit, in terms of recurrence, with the addition of adjuvant tamoxifen therapy, although in one trial the benefit was not statistically significant. Current data suggest that tamoxifen use should be restricted to patients with estrogen receptor-positive DCIS. Neither trial demonstrated a survival benefit with adjuvant tamoxifen. Ongoing and recently completed studies should provide information on outcomes in patients treated with lumpectomy alone and on the effectiveness of aromatase inhibitors as an alternative to tamoxifen.

[Ductal in situ carcinoma: is it ethical to consider the breast conserving therapy as a standard?]

The increasing incidence of DCIS during the past 20 years needs a continuous evaluation of the treatment strategies and a multidisciplinary decision process. The management of the DCIS remains a challenging issue in 2003. Mastectomy should still be considered as the reference treatment which is able to guarantee cure in almost all cases, whereas breast conserving surgery followed by radiation therapy is associated with 7-10% of local recurrence. However, the increasing knowledge of the predictive factors of the local recurrence allows to propose a conservative treatment strategy to a large amount of patients, without negative impact on their prognosis. This review presents the arguments that permit to justify the reasoned choice of the different therapeutic options according to the clinico-pathological situations.

Impact of reproductive factors and lactation on breast carcinoma in situ risk

Incidence rates for breast carcinoma in situ (CIS) have increased markedly over the past 20 years. Breast CIS, detected primarily on mammography, now represents 30-45% of all screened detected breast cancers. We conducted a large population-based case-control study to evaluate the impact of reproductive factors and lactation on breast CIS risk. Case subjects were newly diagnosed with breast CIS at ages 35-64 years between March 1, 1995 and May 31, 1998 (n = 567), resided in Los Angeles County and were born in the United States. Control subjects (n = 614), identified through random digit dialing, fulfilled the same eligibility criteria and were required to have had at least one screening mammogram in the 2-year period before their interview. Women with a positive family history of breast cancer had a 2-fold increase in breast CIS risk. Parous women were at reduced risk relative to nulligravid women (odds ratio [OR] = 0.67, 95% confidence interval [CI] = 0.46-1.00). Among nulliparous women, pregnancy was unrelated to breast CIS risk. Among parous women, risk declined with each additional term pregnancy (p-trend = 0.003). No associations were found with age at first term pregnancy, induced abortion or miscarriage. Long duration of breast-feeding (> or =24 months) was associated with increased risk (OR = 2.00, 95% CI = 1.11-3.60). The observed effects of family history and pregnancy on breast CIS risk are consistent with those observed for invasive breast cancer. The results for breast-feeding are contrary to what has been observed in studies of invasive breast cancer.

Lifetime recreational exercise activity and risk of breast carcinoma in situ

BACKGROUND

The incidence rates of breast carcinoma in situ (BCIS) have increased dramatically over the past two decades, primarily because of increased mammography screening. Ductal carcinoma in situ, which accounts for approximately 85% of BCIS and 10-20% of all breast carcinomas, is generally recognized as the final step in the progression to invasive disease. To the authors' knowledge, few studies have been conducted to date to evaluate BCIS risk factors. Because of its potential effects on circulating sex hormones, physical activity has been proposed as a modifiable risk factor for invasive breast carcinoma. However, the relation to BCIS risk is poorly understood.

METHODS

The authors analyzed data from a population-based case-control study conducted in Los Angeles County. Personal interviews were conducted with 567 white and black women (age range, 35-64 years) who had been newly diagnosed with BCIS between March 1, 1995 and May 31, 1998 and with 1026 control subjects, of whom 616 were screened within 2 years of identification.

RESULTS

After excluding unscreened control subjects (n = 410) and adjusting for potential confounding factors, the risk of BCIS was approximately 35% lower among women with any exercise activity compared with inactive women, although no significant trend was observed. The association between exercise activity and the risk of BCIS was modified by a family history of breast carcinoma. No reduction in risk was observed among women reporting a first-degree family history of breast carcinoma (homogeneity of trends P value = 0.02).

CONCLUSIONS

The findings of the current study suggest that exercise activity may modify the risk of BCIS, particularly among women without a family history of breast carcinoma.

Oral Contraceptives and the Risk of Ductal Breast Carcinoma in situ

Recent evidence suggests that oral contraceptive use is associated with little to no increased risk of invasive breast carcinoma. No study has examined the relationship between oral contraceptive use and the risk of non-invasive breast carcinoma, that is, breast carcinoma in situ.

OBJECTIVE

To define the role of oral contraceptive use in the development of breast carcinoma in situ.

METHODS

The data are 875 ductal carcinoma in situ (DCIS) cases diagnosed among residents of the state of Connecticut from September 15, 1994 to March 14, 1998 and between the age of 20 and 79 years as well as 999 control subjects. Controls are female Connecticut residents collected via random-digit-dial and frequency matched to the cases by 5-year age intervals. Telephone interviews were used to collect information on risk factors and cancer screening history. Logistic regression was used to provide maximum likelihood estimates of the odds ratios (OR) with 95% confidence intervals (95% CI).

RESULTS

The risk of being diagnosed with DCIS for women who had ever used oral contraceptives was not increased relative to women who had never used them (OR: 1.0, 95% CI: 0.8, 1.2). The risk did not significantly increase with duration of oral contraceptive use, nor with duration of high estrogen use, time since last use, progestin or estrogen type, or age at first use. Furthermore, the association between oral contraceptive use and DCIS risk did not vary by the presence of a family history of breast cancer or by menopausal status.

CONCLUSIONS

In these data, no evidence was found for an increased risk of ductal carcinoma in situ associated with the use of oral contraceptives.

Breast carcinoma in situ: risk factors and screening patterns

BACKGROUND

Risk factors associated with invasive breast cancer are well documented, but those associated with breast carcinoma in situ are not well defined.

METHODS

We conducted a population-based, case-control study among female residents of Connecticut to identify risk factors for breast carcinoma in situ. Case patients, diagnosed with ductal carcinoma in situ (DCIS) (n = 875) or lobular carcinoma in situ (LCIS) (n = 123), were matched by 5-year age groups with control subjects (n = 999). Case patients were diagnosed between September 15, 1994, through March 14, 1998, and all subjects were between the ages of 20 and 79 years. Information on risk factors and cancer-screening history was collected by telephone interviews. Conditional logistic regression was used to determine odds ratios (ORs) for the association of these factors with the risk of DCIS and LCIS.

RESULTS

Case patients with DCIS were more likely than control subjects to report a family history of breast cancer (OR = 1.48; 95% confidence interval [CI] = 1.19 to 1.85) or previous breast biopsy (OR = 3.56; 95% CI = 2.86 to 4.43). They also had fewer full-term pregnancies (OR = 0.86; 95% CI = 0.80 to 0.93) and were older at first full-term pregnancy (OR for being 20-29 years old relative to being <20 years old = 1.68; 95% CI = 1.17 to 2.43) and at menopause (OR for being > or =55 years old relative to being <45 years old = 1.71; 95% CI = 1.05 to 2.77). DCIS case patients were more likely than control subjects to have had a mammographic examination (OR = 2.46; 95% CI = 1.78 to 3.40) or an annual clinical breast examination (OR = 1.83; 95% CI = 1.48 to 2.26). DCIS patients and control subjects did not differ with respect to oral contraceptive use, hormone replacement therapy, alcohol consumption or smoking history, or breast self-examination. Associations for LCIS were similar.

CONCLUSIONS

The risk factors associated with DCIS and LCIS are similar to those associated with invasive breast cancer. Diagnosis of DCIS is associated with increased mammography screening.

Trends in breast cancer mortality in Asturias, Spain

While breast cancer mortality rates are subsiding or beginning to decline in many western countries, in Spain they are increasing. We have studied breast cancer mortality rates in Asturias (Spain) by using the age-period-cohort model for the period of 1975-1994. There was an increase in the adjusted rates. The increase of relative risk of death in the period 1990-1994, in relation to that in 1975-1979, was 43%. There is a tendency for successive cohorts to have higher age-specific rates than previous cohorts. Trends in breast cancer mortality rates have been driven predominantly by birth cohort rate trends over the last decades in Asturias, suggesting that the changes in breast cancer mortality have been largely influenced by changes in aetiological factors.