The shape of age-incidence curves of female breast cancer by hormone-receptor status

Comparison of age distribution patterns for different histopathologic types of breast carcinoma

BACKGROUND

Historically, female breast carcinoma has been viewed as an etiologically homogeneous disease associated with rapidly increasing incidence rates until age 50 years, followed by a slower rate of increase among older women. More recent studies, however, have shown distinct age incidence patterns for female breast cancer when stratified by estrogen receptor (ER) expression and/or histopathologic subtypes, suggesting etiologic heterogeneity.

MATERIALS AND METHODS

To determine if different age incidence patterns reflect etiologic heterogeneity (more than one breast cancer type within the general breast carcinoma), we applied "smoothed" age histograms at diagnosis (density plots) and a two-component statistical mixture model to all breast carcinoma cases (n = 270,124) in the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute. These overall patterns were then reevaluated according to histopathologic type, race, and ER expression.

RESULTS

A bimodal age distribution at diagnosis provided a better fit to the data than a single density for all breast carcinoma populations, except for medullary carcinoma. Medullary carcinomas showed a single age distribution at diagnosis irrespective of race and/or ER expression.

CONCLUSIONS

Distinct age-specific incidence patterns reflected bimodal breast cancer populations for breast carcinoma overall as well as for histopathologic subtypes, race, and ER expression. The one exception was medullary carcinoma. Of note, medullary carcinomas are rare tumors, which are associated with germ-line mutations in the BRCA1 gene. These descriptive and model-based results support emerging molecular data, suggesting two main types of breast carcinoma in the overall breast cancer population.

Dietary lignan intake and postmenopausal breast cancer risk by estrogen and progesterone receptor status

BACKGROUND

Studies conducted in Asian populations have suggested that high consumption of soy-based foods that are rich in isoflavone phytoestrogens is associated with a reduced risk of breast cancer. However, the potential associations of other dietary phytoestrogens--i.e., the lignans or their bioactive metabolites, the enterolignans--with the risk of breast cancer are unclear.

METHODS

We prospectively examined associations between the risk of postmenopausal invasive breast cancer and dietary intakes of four plant lignans (pinoresinol, lariciresinol, secoisolariciresinol, and matairesinol) and estimated exposure to two enterolignans (enterodiol and enterolactone), as measured with a self-administered diet history questionnaire, among 58,049 postmenopausal French women who were not taking soy isoflavone supplements. Relative risks (RRs) and 95% confidence intervals (CIs) were estimated using multivariable Cox proportional hazards regression models. Analyses were further stratified by the combined estrogen and progesterone receptor (ER/PR) status of the tumors. Statistical tests were two-sided.

RESULTS

During 383,425 person-years of follow-up (median follow-up, 7.7 years), 1469 cases of breast cancer were diagnosed. Compared with women in the lowest intake quartiles, those in the highest quartile of total lignan intake (>1395 microg/day) had a reduced risk of breast cancer (RR = 0.83, 95% CI = 0.71 to 0.95, P(trend) = .02, 376 versus 411 cases per 100,000 person-years), as did those in the highest quartile of lariciresinol intake (RR = 0.82, 95% CI = 0.71 to 0.95, P(trend) = .01). The inverse associations between phytoestrogen intakes and postmenopausal breast cancer risk were limited to ER- and PR-positive disease (e.g., RR for highest versus lowest quartiles of total plant lignan intake = 0.72, 95% CI = 0.58 to 0.88, P(trend) = .01, 174 versus 214 cases per 100,000 person-years, and RR for highest versus lowest quartiles of total enterolignan level = 0.77, 95% CI = 0.62 to 0.95, P(trend) = .01, 164 versus 204 cases per 100,000 person-years).

CONCLUSIONS

High dietary intakes of plant lignans and high exposure to enterolignans were associated with reduced risks of ER- and PR-positive postmenopausal breast cancer in a Western population that does not consume a diet rich in soy.

Body Size and Risk for Breast Cancer in Relation to Estrogen and Progesterone Receptor Status in Japan

PURPOSE

The aim of this study is to examine the association of height, weight, and body mass index (BMI) with breast cancer and its hormone receptor-defined subtype in a low-risk population.

METHODS

We identified 441 newly diagnosed cases of breast cancer during a 9.9-year follow-up of a population-based cohort consisting of 55,537 women aged 40 to 69 years. Body size was assessed by using a self-administered questionnaire.

RESULTS

We found a significant positive association of height and marginally significant positive associations of weight and BMI with breast cancer in postmenopausal women. Weight and BMI were associated more strongly with estrogen receptor-positive (ER+) than ER-negative (ER-) breast cancer in postmenopausal women. BMI was related significantly to increased risk for ER+ (hazard ratio [HR] per BMI increment of 1 kg/m2, 1.08; 95% confidence interval [CI], 1.01-1.15), but not ER- breast cancer (HR per BMI increment of 1 kg/m2, 0.95; 95% CI, 0.84-1.06; p for difference of HRs=0.048).

CONCLUSIONS

The present study suggests that height, weight, and BMI are associated with increased risk for breast cancer among postmenopausal women in Japan. The positive association of weight and BMI might be limited to ER+ breast cancer.

Role and impact of menstrual and reproductive factors on breast cancer risk in Japan

The aim of this study was to clarify the role and impact of menstrual and reproductive factors in relation to breast cancer and its hormone receptor-defined subtype, overall and separately among premenopausal and postmenopausal women in a low-risk population, using data from the Japan Public Health Center-based Prospective study. A total of 55 537 women aged 40-69 years completed a self-administered questionnaire, which included items about menstrual and reproductive history. During 1990-2002, 441 newly diagnosed cases of breast cancer were identified. Early age at menarche for premenopausal women, late age at natural menopause, nulliparity and low parity for both premenopausal and postmenopausal women, and late age at first birth for postmenopausal women were significantly associated with an increased risk of breast cancer. No overall significant associations were seen between the use of exogenous female hormones or breast feeding and breast cancer risk. Age at menarche and age at natural menopause were somewhat more closely associated with the risk of progesterone receptor-negative than positive breast cancer although no difference was observed for estrogen receptor status. Risks associated with parity, number of births and age at first birth did not significantly differ by hormone receptor-defined breast cancer. Our findings suggest that menstrual and reproductive factors may play an important role in the development of breast cancer among low-risk populations, similarly as they do in Western populations, and that risk factors might differ by hormone receptor status.

Differences in risk factors for breast cancer molecular subtypes in a population-based study

Analysis of gene expression data suggests that breast cancers are divisible into molecular subtypes which have distinct clinical features. This study evaluates whether pathologic features and etiologic associations differ among molecular subtypes. We evaluated 804 women with invasive breast cancers and 2,502 controls participating in a Polish Breast Cancer Study. Immunohistochemical stains for estrogen receptor alpha, progesterone receptor, human epidermal growth factor receptors (HER2 and HER1), and cytokeratin 5 were used to classify cases into five molecular subtypes: luminal A, luminal B, HER2-expresing, basal-like, and unclassified. Relative risks were estimated using adjusted odds ratios and 95% confidence intervals. We observed that compared with the predominant luminal A tumors (69%), other subtypes were associated with unfavorable clinical features at diagnosis, especially HER2-expressing (8%) and basal-like (12%) tumors. Increasing body mass index significantly reduced the risk of luminal A tumors among premenopausal women (odds ratios, 0.71; 95% confidence intervals, 0.57-0.88 per five-unit increase), whereas it did not reduce risk for basal-like tumors (1.18; 0.86-1.64; P(heterogeneity) = 0.003). On the other hand, reduced risk associated with increasing age at menarche was stronger for basal-like (0.78; 0.68-0.89 per 2-year increase) than luminal A tumors (0.90; 0.95-1.08; P(heterogeneity) = 0.0009). Although family history increased risk for all subtypes (except for unclassified tumors), the magnitude of the relative risk was highest for basal-like tumors. Results from this study have shown that breast cancer risk factors may vary by molecular subtypes identified in expression studies, suggesting etiologic, in addition to clinical, heterogeneity of breast cancer.

Intake of fruits, and vegetables in relation to breast cancer risk by hormone receptor status

SUMMARY

The inconsistent associations between fruit and vegetable intake and breast cancer risk may be due to heterogeneity of associations by estrogen (ER) and progesterone receptor (PR) status of the tumors. We evaluated this hypothesis in a large (2,386 cases and 2,503 controls) population-based case-control study in Poland, conducted between 2000 and 2003. We observed significant associations between reduced overall risk of breast cancer and increasing levels of total fruit intake (odds ratio (OR) for highest versus lowest quartile = 0.76, 95%CI = 0.63-0.91; p-trend = 0.01), but not for total vegetable intake (1.13 (0.93-1.37), p-trend = 0.25), after controlling for age, energy intake and known risk factors for breast cancer. The inverse association with total fruit intake was stronger for risk of ER+ (0.69 (0.54-0.88), p-trend = 0.01) than ER- tumors (0.89 (0.67-1.19), p-trend = 0.57) (p-heterogeneity = 0.02). In conclusion, this study suggests that fruit intake might have differential associations for breast tumor subtypes defined by ER status.

Hormone-related risk factors for breast cancer in women under age 50 years by estrogen and progesterone receptor status: results from a case-control and a case-case comparison

INTRODUCTION

It has been suggested that hormonal risk factors act predominantly on estrogen receptor and progesterone receptor (ER/PR)-positive breast cancers. However, the data have been inconsistent, especially in younger women.

METHODS

We evaluated the impact of age at menarche, pregnancy history, duration of breastfeeding, body mass index, combined oral contraceptive use, and alcohol consumption on breast cancer risk by ER/PR status in 1,725 population-based case patients and 440 control subjects aged 20 to 49 years identified within neighborhoods of case patients. We used multivariable unconditional logistic regression methods to conduct case-control comparisons overall as well as by ER/PR status of the cases, and to compare ER+PR+ with ER-PR- case patients.

RESULTS

The number of full-term pregnancies was inversely associated with the risk of ER+PR+ breast cancer (ptrend = 0.005), whereas recent average alcohol consumption was associated with an increased risk of ER+PR+ breast cancer (ptrend = 0.03). Neither of these two factors was associated with the risk of ER- PR- breast cancer. Late age at menarche and a longer duration of breastfeeding were both associated with decreased breast cancer risk, irrespective of receptor status (all ptrend< or = 0.03).

CONCLUSION

Our results suggest that the number of full-term pregnancies and recent alcohol consumption affect breast cancer risk in younger women predominantly through estrogen and progesterone mediated by their respective receptors. Late age at menarche and breastfeeding may act through different hormonal mechanisms.

Reproductive factors and breast cancer risk according to joint estrogen and progesterone receptor status: a meta-analysis of epidemiological studies

Introduction

Although reproductive factors have been known for decades to be associated with breast cancer risk, it is unclear to what extent these associations differ by estrogen and progesterone receptor (ER/PR) status. This report presents the first meta-analysis of results from epidemiological studies that have investigated parity, age at first birth, breastfeeding, and age at menarche in relation to ER⁺PR⁺ and ER^-PR^- cancer risk.

Materials and methods

We calculated summary relative risks (RRs) and corresponding 95% confidence intervals (CIs) using a fixed effects model.

Results

Each birth reduced the risk of ER⁺PR⁺ cancer by 11% (RR per birth = 0.89, 95% CI = 0.84–0.94), and women who were in the highest age at first birth category had, on average, 27% higher risk of ER⁺PR⁺ cancer compared with women who were in the youngest age at first birth category (RR = 1.27, 95% CI = 1.07–1.50). Neither parity nor age at first birth was associated with the risk of ER^-PR^- cancer (RR per birth = 0.99, 95% CI = 0.94–1.05; RR of oldest versus youngest age at first birth category = 1.01, 95% CI = 0.85–1.20). Breastfeeding and late age at menarche decreased the risk of both receptor subtypes of breast cancer. The protective effect of late age at menarche was statistically significantly greater for ER⁺PR⁺ than ER^-PR^- cancer (RR = 0.72 for ER⁺PR⁺ cancer; RR = 0.84 for ER^-PR^- cancer, p for homogeneity = 0.006).

Conclusion

Our findings suggest that breastfeeding (and age at menarche) may act through different hormonal mechanisms than do parity and age at first birth.

Estrogen deprivation for breast cancer prevention

Estrogen deprivation (ED) either as a result of a natural or artificial menopause or the use of aromatase inhibitors in postmenopausal women results in a reduction of the incidence of breast cancer. Two major clinical trials of this approach comparing anastrozole or exemestane with placebo are currently in progress to test their efficacy for prevention. Reduction of contralateral breast lesions by at least 50% compared with tamoxifen indicate this approach has promise. The target lesion within the breast for ED is not known but we argue that hyperplastic enlarged lobular units (HELUs) as well as more advanced lesions are good candidates. A major problem for ED is de novo or acquired resistance to its effectiveness. We discuss potential mechanisms of resistance including high concentrations of tissue estrogens, increase in growth factor, and signal transduction pathways within the epithelial cell and activation of paracrine pathways from breast adipocytes, macrophages and fibroblasts. It may be possible to increase effectiveness of ED by additional preventive agents or by lifestyle alterations.

The aged breast

There is a clear association between the development of breast cancer and increasing age, with 80% of cancers occurring in women more than 50 years of age and one-third in women over 70 years. Following the menopause the breast undergoes involution, with the main changes affecting the terminal ductal lobular unit. There is an increase in oestrogen receptor alpha (ERalpha)-positive cells, a decrease in proliferation but, in comparison to premenopausal breasts, a greater number of ERalpha-proliferating cells. The breast cancers that occur in women >/= 75 years are more likely to be ER-positive, with a low growth rate and limited expression of HER-2 and p53. It is proposed that uneven involution of the breast, the persistence of at-risk lesions, the presence of ERalpha-proliferating cells and local oestrogen metabolism in breast adipose tissue are factors in the development of breast cancers with a well-differentiated phenotype.

Ethnic differences in the time trend of female breast cancer incidence: Singapore, 1968-2002

BACKGROUND

From 1968 to 2002, Singapore experienced an almost three-fold increase in breast cancer incidence. This increase appeared to be different across the three main ethnic groups: Chinese, Malays and Indians. This paper used age-period-cohort (APC) modelling, to determine the effects of age at diagnosis, calendar period, and birth cohort on breast cancer incidence for each ethnic group.

METHODS

This study included all breast cancer cases (n = 15,269) in the three ethnic groups, reported to the Singapore Cancer Registry from 1968 to 2002 between the ages 25 to 79. Age-specific fertility rates from the Department of Statistics were used to explore the role of fertility.

RESULTS

In the 1970s, Indian women had the highest age-standardized breast cancer but by the mid-1980s the highest rates were seen among the Chinese. Remarkable differences were seen in the age-specific incidence rates by ethnic groups. After age 49, the incidence rates for the Chinese and Malays leveled off whereas it continued to rise in the Indians. While our analyses provided some evidence that an age-drift model described the trend seen in the Indians, age-period-cohort model and age-cohort model had the best fit for the Chinese and Malays aged 25 to 79 respectively. Overall, Chinese and Malay women born in later cohorts were at increased risk of developing breast cancer relative to their counterparts in the earlier cohorts. The three ethnic groups experienced similar changes in their fertility in the 1970s, which likely explained much of the increase in their breast cancer incidence but not the ethnic differences. There was a stronger inverse association between total fertility rate and pre-menopausal breast cancer incidence in the Chinese and Malays than the Indians.

CONCLUSION

The observed dissimilarity among ethnic groups suggests ethnic differences in exposure or response to certain risk factors. It is likely that longer and subtler differences in childbearing trends and other risk factors may further explain these ethnic differences.

Body weight and postmenopausal breast cancer risk defined by estrogen and progesterone receptor status among Swedish women: A prospective cohort study

Although obesity is one of the established risk factors for postmenopausal breast cancer, it is not clear whether this positive association differs across estrogen receptor (ER) and progesterone receptor (PR) status of breast tumors. We evaluated the association between body weight and ER/PR defined breast cancer risk stratified by postmenopausal hormone (PMH) use and a family history of breast cancer in the population-based Swedish Mammography Screening Cohort comprising 51,823 postmenopausal women. Relative body weight was measured by body mass index (kg/m2) based on self-reported weight and height collected in 1987 and 1997. Relative risks (RRs) were estimated by hazard ratios derived from Cox proportional hazards regression models. During an average of 8.3-year follow-up, 1,188 invasive breast cancer cases with known ER and PR status were diagnosed. When comparing to normal weight group, we observed a positive association between obesity and risk for the development of ER+ PR+ tumors (RR = 1.67, 95% CI = 1.34-2.07) and an inverse association for the development of all PR- tumors (RR = 0.68, 95% CI = 0.47-0.98). Statistically significant heterogeneity was observed in the RRs between ER+ PR+ tumors and all PR- tumors (p(heterogeneity) < 0.0001). The positive association of obesity with the development of ER+ PR+ tumors was confined to never-users of PMHs (RR = 1.90 (CI 95%:1.38-2.61)) and to those without a family history of breast cancer (RR = 1.82 (CI 95%:1.45-2.29)). Our results support the hypothesis that excess endogenous estrogen due to obesity contributes to an increased risk of ER+ PR+ postmenopausal breast cancer.

A comparison of the pattern of occurrence of breast cancer in Nigerian and British women

Studies have suggested a predominance of premenopausal breast cancer in black compared to white women. The aim of the study was to compare the age specific incidence of breast cancer in Nigerian and British women. The mean age at presentation was 43.1 and 64 years for Jos (Nigeria) and Norfolk (United Kingdom), respectively. The age specific incidence rates were higher in women above 50 years compared to women less than 50 years of age in both populations. The odds of having breast cancer for women aged less than 50 years is 3.0 times higher in Norfolk (95% Confidence Interval 2.0-4.4) than Jos and 9.0 times higher for women over 50 years of age in Norfolk (95% Confidence Interval 5.3-18.3) than Jos. The age specific incidence rates are higher for postmenopausal women in both populations; with higher rates for all age groups in the United Kingdom population.

Established breast cancer risk factors by clinically important tumour characteristics

Breast cancer is a morphologically and clinically heterogeneous disease; however, it is less clear how risk factors relate to tumour features. We evaluated risk factors by tumour characteristics (histopathologic type, grade, size, and nodal status) in a population-based case-control of 2386 breast cancers and 2502 controls in Poland. Use of a novel extension of the polytomous logistic regression permitted simultaneous modelling of multiple tumour characteristics. Late age at first full-term birth was associated with increased risk of large (> 2 cm) tumours (odds ratios (95% confidence intervals) 1.19 (1.07-1.33) for a 5-year increase in age), but not smaller tumours (P for heterogeneity adjusting for other tumour features (Phet) = 0.007). On the other hand, multiparity was associated with reduced risk for small tumours (0.76 (0.68-0.86) per additional birth; Phet = 0.004). Consideration of all tumour characteristics simultaneously revealed that current or recent use of combined hormone replacement therapy was associated with risk of small (2.29 (1.66-3.15)) and grade 1 (3.36 (2.22-5.08)) tumours (Phet = 0.05 for size and 0.0008 for grade 1 vs 3), rather than specific histopathologic types (Phet = 0.63 for ductal vs lobular). Finally, elevated body mass index was associated with larger tumour size among both pre- and postmenopausal women (Phet = 0.05 and 0.0001, respectively). None of these relationships were explained by hormone receptor status of the tumours. In conclusion, these data support distinctive risk factor relationships by tumour characteristics of prognostic relevance. These findings might be useful in developing targeted prevention efforts.

What can be learnt from models of incidence rates?

Models of breast cancer incidence have evolved from the observation by Armitage and Doll in the 1950s that the pattern of incidence by age differs for reproductive cancers from those of other major malignancies. Both two-stage and multistage models have been applied to breast cancer incidence. Consistent across modeling approaches, risk accumulation or the rate of increase in breast cancer incidence is most rapid from menarche to first birth. Models that account for the change in risk after menopause and the temporal sequence of reproductive events summarize risk efficiently and give added insights to potentially important mechanistic features. First pregnancy has an adverse impact on progesterone receptor negative tumors, while increasing parity reduces the risk of estrogen/progesterone receptor positive tumors but not estrogen/progesterone receptor negative tumors. Integrated prediction models that incorporate prediction of carrier status for highly penetrant genes and also account for lifestyle factors, mammographic density, and endogenous hormone levels remain to be efficiently implemented. Models that both inform and reflect the emerging understanding of the molecular and cell biology of carcinogenesis are still a long way off.

Patterns of cancer incidence, mortality, and prevalence across five continents: defining priorities to reduce cancer disparities in different geographic regions of the world

Efforts to reduce global cancer disparities begin with an understanding of geographic patterns in cancer incidence, mortality, and prevalence. Using the GLOBOCAN (2002) and Cancer Incidence in Five Continents databases, we describe overall cancer incidence, mortality, and prevalence, age-adjusted temporal trends, and age-specific incidence patterns in selected geographic regions of the world. For the eight most common malignancies-cancers of lung, breast, colon and rectum, stomach, prostate, liver, cervix, and esophagus-the most important risk factors, cancer prevention and control measures are briefly reviewed. In 2002, an estimated 11 million new cancer cases and 7 million cancer deaths were reported worldwide; nearly 25 million persons were living with cancer. Among the eight most common cancers, global disparities in cancer incidence, mortality, and prevalence are evident, likely due to complex interactions of nonmodifiable (ie, genetic susceptibility and aging) and modifiable risk factors (ie, tobacco, infectious agents, diet, and physical activity). Indeed, when risk factors among populations are intertwined with differences in individual behaviors, cultural beliefs and practices, socioeconomic conditions, and health care systems, global cancer disparities are inevitable. For the eight most common cancers, priorities for reducing cancer disparities are discussed.

Fruits, vegetables, and micronutrient intake in relation to breast cancer survival

OBJECTIVE

To determine whether fruit, vegetable, and micronutrient intake 1 year prior to breast cancer diagnosis is associated with a reduction in the subsequent risk of all-cause or breast cancer-specific mortality.

METHODS

Follow-up data from 1,235 invasive breast cancer cases age 25-98 years from the Long Island Breast Cancer Study Project were analyzed. At the 1996-1997 case-control interview, respondents completed a food frequency questionnaire, which assessed dietary intake of fruits, vegetables, and vitamin supplement use in the previous 12 months. All-cause mortality (n=186 deaths) and breast cancer-specific mortality status (n=125 deaths, 67.2%) were determined through December 31, 2002.

RESULTS

Hazard ratios (HRs) for all-cause mortality were insignificantly reduced for intake of any fruits, fruit juices, and vegetables (HR=0.68, 95% CI: 0.42-1.09) and leafy vegetables (HR=0.72, 95% CI: 0.41-1.24) among post-menopausal women only. Both of these associations were more pronounced among those with ER+PR+ tumors (HR=0.54, 95% CI: 0.27-1.10, and HR=0.66, 95% CI: 0.33-1.31, respectively). Similar associations were observed for breast cancer-specific mortality.

CONCLUSIONS

In a cohort of women diagnosed with breast cancer, higher intake of fruits, vegetables, and micronutrients was associated with a non-significant survival advantage in post-menopausal women only.

Clinical Stage of Breast Cancer by Parity, Age at Birth, and Time Since Birth: A Progressive Effect of Pregnancy Hormones?

Breast cancer diagnosed during pregnancy or 1 to 2 years after birth often occurs at a late stage. Little is known about tumor characteristics in the high-risk period shortly after a childbirth. We here explore whether stage of disease differs according to timing of births. Results are based on 22,351 Norwegian breast cancer patients of parity 0 to 5, ages 20 to 74 years. The proportion of stage II to IV tumors was considerably higher among parous than nulliparous women at age <30 years (52.7% versus 36.8%, P=0.009), but similar or lower in other age groups (P(interaction)=0.029). In general, the largest proportion of stage II to IV tumors was found among women diagnosed during pregnancy or <2 years after birth. However, among women with late-age births (first or second birth >or=30 years, third birth >or=35 years), as well as women with an early second birth (<25 years), the proportion with advanced disease was rather similar or even higher among those diagnosed 2 to 6 years after birth (49.3-56.0%). The association between clinical stage and time since birth reached statistical significance among women with a late first or second birth and among all triparous women (P <or= 0.032). The subgroups with a high proportion of advanced disease 2 to 6 years after birth corresponded quite well to those previously found to have the most pronounced transient increase in risk after birth. Thus, pregnancy hormones may have a progressive effect on breast cancer tumors in addition to a possible promoting effect. A potential effect of prolactin is discussed.

A French national survey on infiltrating breast cancer: analysis of clinico-pathological features and treatment modalities in 1159 patients

BACKGROUND

Despite the approximate 42,000 yearly new cases of breast cancer in France, there have been very few exhaustive studies on the clinicopathological features and treatment options of this disease.

METHODS

Thus, a prospective, non-selective, nationwide survey on infiltrating breast cancer (IBC) was conducted in France from September 2001 to April 2002, in order to assess the epidemiological features of newly diagnosed disease, the prognostic and predictive variables with a special emphasis on hormone receptors, and the current approaches to therapy in everyday clinical practice.

RESULTS

In total, 1159 patients were evaluable (median age 57 years); two-thirds of women were postmenopausal and 38% had undergone hormonal replacement therapy (HRT). Ductal and lobular infiltrating cancers represented 82.3% and 11.6% of cases, respectively. Most tumours expressed oestrogen (79.7%) and progesterone (69.7%) receptors. Overexpression of the human epidermal growth factor receptor-2 oncogene was found in 20.6% of the assessed cases. IBC diagnosed in women under HRT presented significantly better clinico-pathological features than in non-users. All patients underwent surgery as first treatment: 77.5% breast-conserving surgery (BCS) and 22.5% mastectomy; 1024 patients also underwent axillary surgery. The overall axillary lymph-node involvement rate was 44.4%. Radiotherapy was proposed in 98% and 83% of the women who had undergone BCS and mastectomy, respectively. Adjuvant chemotherapy was delivered in 58.7% of patients and hormonal treatment was provided in 76.5% of patients; tamoxifen was the most widely used hormonal treatment.

CONCLUSIONS

This study showed a trend for global downstaging of IBC (with favourable clinico-pathological features), leading to a high rate of BCS. Postoperative treatments were widely used, in accordance with national and international guidelines. Use of aromatase inhibitors and taxanes was limited, but is likely to rise in the future.

Content of 8-Hydroxy-2-Deoxyguanosine in Steroid Receptor-Positive and Receptor-Negative Breast Cancer Cells

The content of DNA damage marker 8-hydroxy-2-deoxyguanosine in 16 receptor-negative and 18 receptor-positive human breast neoplasms was measured by immunohistochemical methods. Positive staining was revealed in 81.3 and 50.0% samples of groups 1 and 2, respectively. The effect of arylhydrocarbon receptor agonist beta-naphthoflavone on the content of 8-hydroxy-2-deoxyguanosine and number of estrogen and progesterone receptors was evaluated in MCF-7 breast cancer cells. The degree of genotoxic damage significantly increased 1 h after combined treatment with estradiol and beta-naphthoflavone (in contrast to individual treatment) and remained practically unchanged in the follow-up period. According to the estrogen effect-switching phenomenon, genotoxic damage can contribute to the development of R(-)-breast cancer.

Distinct breast cancer incidence and prognostic patterns in the NCI's SEER program: suggesting a possible link between etiology and outcome

BACKGROUND

Breast cancer is a heterogeneous and chronic disease with relapses and death occurring 25 years or more after primary diagnosis. Standard tumor characteristics are used to predict initial relapse or death, but their ability to estimate long-term patterns of failure may be limited.

METHODS

To further evaluate the significance of standard tumor features, we compared incidence and prognostic patterns in the National Cancer Institute's (NCI's) large-scale population-based Surveillance, Epidemiology, and End Results (SEER) program for high-risk versus low-risk breast cancers, i.e., size > 2.0 versus < or = 2.0 cm, lymph node positive versus negative, high versus low histologic grade, and hormone receptor negative versus positive expression, respectively. Data were stratified by age 50 years to approximate menopause.

RESULTS

High-risk versus low-risk breast cancers demonstrated two very different incidence and prognostic patterns. Age-specific incidence rates among women with high-risk tumors increased until age 50 years then flattened, whereas rates among women with low-risk tumors increased continuously with aging. Hazard rates for breast cancer death spiked sharply two years following primary breast cancer diagnosis among women with high-risk but not with low-risk tumors. Paradoxically, hazard function crossed over 6-8 years following breast cancer diagnosis, with hazard rates lower for high-risk than for low-risk breast cancers.

CONCLUSION

Distinct incidence and prognostic patterns among high-risk and low-risk breast cancers suggest a possible link between breast cancer etiology and outcome. These epidemiologic results appear to complement emerging molecular genetic techniques, showing distinct genotypes for high-risk and low-risk breast cancer phenotypes.

Global trends in breast cancer incidence and mortality 1973-1997

BACKGROUND

Worldwide, breast cancer is the most common cancer and is the leading cause of cancer death among women.

METHODS

To describe global trends, we compared age-adjusted incidence and mortality rates over three decades (from 1973-77 to 1993-97) and across several continents.

RESULTS

Both breast cancer incidence and mortality rates varied 4-fold by geographic location between countries with the highest and lowest rates. Recent (1993-1997) incidence rates ranged from 27/100,000 in Asian countries to 97/100,000 among US white women. Overall, North American and northern European countries had the highest incidence rates of breast cancer; intermediate levels were reported in Western Europe, Oceania, Scandinavia, and Israel; and Eastern Europe, South and Latin America, and Asia had the lowest levels. Breast cancer incidence rose 30-40% from the 1970s to the 1990s in most countries, with the most marked increases among women aged > or =50 years. Mortality from breast cancer paralleled incidence: it was highest in the countries with the highest incidence rates (between 17/100,000 and 27/100,000), lowest in Latin America and Asia (7-14/100,000), and rose most rapidly in countries with the lowest rates.

CONCLUSIONS

Breast cancer incidence and mortality rates remain highest in developed countries compared with developing countries, as a result of differential use of screening mammograms and disparities in lifestyle and hereditary factors. Future studies assessing the combined contributions of both environmental and hereditary factors may provide explanations for worldwide differences in incidence and mortality rates.

Differences in Breast Cancer Risk Factors by Tumor Marker Subtypes among Premenopausal Vietnamese and Chinese Women

We evaluated associations between reproductive and lifestyle risk factors with breast cancer tumor marker status in a case-control study. Cases were premenopausal women living in Vietnam and China who were eligible for a clinical trial of oophorectomy and tamoxifen as treatment for breast cancer (n = 682). Controls were nonrelative hospital visitors, matched on age to the cases (n = 649). Immunohistochemical analysis was used to identify the presence of estrogen receptor (ER) and progesterone receptor and the overexpression of HER-2/neu oncogene. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using unconditional logistic regression, adjusted for known confounders. Overall, 280 (61%) tumor samples were ER positive and 176 (38%) were ER negative. HER-2/neu overexpression was detected in 161 (35%) samples, whereas 286 (26%) samples were HER-2/neu negative. We observed an inverse trend between increasing parity and decreasing breast cancer risk (P = 0.002). Women ages ≥25 years at first birth had increased breast cancer risk compared with women ages &lt;25 years at first birth (OR, 1.53; 95% CI, 1.20-1.95). Women who consumed alcohol had increased risk of breast cancer compared with women who did not (OR,1.85; 95% CI, 1.32-2.61). Compared with controls, OR estimates for breast cancer by parity and age at first birth were significantly associated with ER and/or HER-2/neu tumor status by Wald test (P &lt; 0.05). Family history, age at menarche, cumulative lactation, body mass index, and education were not significantly related to breast cancer risk. Our findings support the hypothesis that some breast cancer risk factors differ by ER and HER-2/neu tumor marker subtypes.

A Predictive Model for the Development of Hormone-Responsive Breast Cancer

BACKGROUND

Effective therapies to reduce the risk of hormone-sensitive breast cancers (ER or PR positive) exist. Available models predict the risk of breast cancer without addressing hormone receptor status. The purpose of this study was to identify risk factors predictive of the development of hormone-sensitive cancers.

METHODS

A total of 1285 invasive breast cancers in 1263 women were identified from a prospectively maintained database. Risk factors were compared for ER+ and ER- cancers by using Fisher's exact test.

RESULTS

Models were developed for premenopausal and postmenopausal women. In premenopausal women, white race, age at menarche < 12 years, and nulliparity or age at first birth > 20 years were used. The risk of ER+ cancer increased from 67.7% with 0 variables to 83.8% with all three (P = .013). In postmenopausal women, white race and a history of estrogen therapy were used. With none of the variables present, the incidence of ER+ cancer was 70.0%; it was 77.6% with one variable and 85.4% with both variables (P = .002). In postmenopausal women, variables predicted significant differences in hormone sensitivity only for those aged < or = 60 years. In the subset of women with information on alcohol use, adding this variable to the model improved the prediction of hormonal status.

CONCLUSIONS

Our findings, if prospectively validated, may help identify those who would obtain the greatest benefit from hormonal chemoprevention strategies for breast cancer risk reduction.

Polycyclic aromatic hydrocarbon-DNA adducts and breast cancer: a pooled analysis

Polycyclic aromatic hydrocarbon (PAH)-DNA adducts have been associated with breast cancer in several small studies. The authors' pooled analysis included 873 cases and 941 controls from a population-based case-control study. Competitive enzyme-linked immunosorbent assay in peripheral mononuclear cells was conducted in 2 rounds, and results were pooled on the basis of round-specific quantiles. The odds ratio for breast cancer was elevated in relation to detectable PAH-DNA adducts (1.29 as compared with nondetectable adduct levels; 95% confidence interval = 1.05, 1.58), but there was no apparent dose-response relationship with increasing quantiles. No consistent pattern emerged when the results were stratified by PAH sources (e.g., active cigarette smoking or PAH-containing foods), or when the cases were categorized by stage of disease or hormone receptor status. These data provide only modest support for an association between PAH-DNA adducts and breast cancer development.

Distinct incidence patterns among in situ and invasive breast carcinomas,with possible etiologic implications

BACKGROUND

Incidence patterns are well-established for invasive breast carcinoma (InvBC) overall and for InvBC defined by estrogen receptor (ER) expression, but are not as well-defined for breast carcinoma in situ (CIS).

METHODS

We, therefore, examined and compared the incidence patterns for CIS and InvBC in the SEER program to define these patterns and to generate etiologic hypotheses. Data were stratified by age < 50 and > or =50 years to approximate menopause.

RESULTS

During the years 1973-2000, annual age-adjusted incidence rates rose 660% for CIS and 36% for InvBC, with the most rapid increases occurring in women age > or =50 years. Age-specific incidence rate curves for CIS increased until age 50 years, and then flattened, irrespective of ER expression. On the other hand, rates for InvBC overall and for InvBC defined by ER-positive expression increased continuously with aging, whereas rates for InvBC defined by ER-negative expression flattened after 50 years. Age frequency distribution for CIS and for ER-negative InvBC demonstrated bimodal populations, with a predominant early onset peak incidence at age 50 years. Age frequency distribution for ER-positive InvBC showed bimodal populations with a predominant late-onset mode at age 71 years.

CONCLUSION

Over the last three decades, age-adjusted incidence trends differed for CIS and InvBC in the United States, possibly due to screening mammography and/or etiologic diversity. Indeed, age-specific incidence patterns suggested that carcinogenic events operating early in reproductive life had greater impact upon CIS and InvBC defined by ER-negative expression than upon InvBC overall and InvBC defined by ER-positive expression.

Environmental tobacco smoke and breast cancer incidence

To evaluate whether environmental tobacco smoke (ETS) influences breast cancer incidence, data from a population-based case-control study were analyzed. Respondents with available ETS information assessed by in-person questionnaires included 1356 newly diagnosed cases and 1383 controls. Relative to nonsmokers who reported no residential ETS exposure throughout the life course, the odds ratios (OR) for breast cancer were not substantially elevated in relation to ETS exposure, active smoking, or a joint measure of active and passive smoking (OR, 1.15, 95% CI, 0.90, 1.48). An increased OR, however, was noted among nonsmokers who lived with a smoking spouse for over 27 years (2.10, 95% CI, 1.47, 3.02), although no dose-response was evident. Also, among women with hormone-receptor-positive tumors only, the OR for both active and passive smoking was increased (1.42 for ER+ PR+, 95% CI, 1.00, 2.00). Our data suggest that if there is an effect for ETS on breast cancer, that effect is restricted to selected subgroups of women, such as those with long-term exposure from a smoking spouse.

Etiology of Hormone Receptor–Defined Breast Cancer: A Systematic Review of the Literature

Breast cancers classified by estrogen receptor (ER) and/or progesterone receptor (PR) expression have different clinical, pathologic, and molecular features. We examined existing evidence from the epidemiologic literature as to whether breast cancers stratified by hormone receptor status are also etiologically distinct diseases. Despite limited statistical power and nonstandardized receptor assays, in aggregate, the critically evaluated studies (n = 31) suggest that the etiology of hormone receptor–defined breast cancers may be heterogeneous. Reproduction-related exposures tended to be associated with increased risk of ER-positive but not ER-negative tumors. Nulliparity and delayed childbearing were more consistently associated with increased cancer risk for ER-positive than ER-negative tumors, and early menarche was more consistently associated with ER-positive/PR-positive than ER-negative/PR-negative tumors. Postmenopausal obesity was also more consistently associated with increased risk of hormone receptor–positive than hormone receptor–negative tumors, possibly reflecting increased estrogen synthesis in adipose stores and greater bioavailability. Published data are insufficient to suggest that exogenous estrogen use (oral contraceptives or hormone replacement therapy) increase risk of hormone-sensitive tumors. Risks associated with breast-feeding, alcohol consumption, cigarette smoking, family history of breast cancer, or premenopausal obesity did not differ by receptor status. Large population-based studies of determinants of hormone receptor–defined breast cancers defined using state-of-the-art quantitative immunostaining methods are needed to clarify the role of ER/PR expression in breast cancer etiology.

Models of Breast Cancer Growth and Investigations of Adjuvant Surgical Oophorectomy

Clinical observations of the natural history of breast cancer and its response to a variety of therapeutic interventions have contributed to changing concepts about the growth and metastatic spread of this disease. Increased attention has been given to tumor cell dormancy and the occurrence of greatly delayed metastatic disease development, which has been important to rethinking therapy. Although gene profiling of breast tumors recently has highlighted the importance of individual tumor characteristics in patients' prognosis, considerable data also support the concept of breast cancer as a problem of macro- and microenvironmental regulatory imbalance and dynamic chaos. Observations of unexpectedly large survival benefits from adjuvant surgical oophorectomy done in the luteal phase of the menstrual cycle in premenopausal women are consistent with an interpretation that extratumoral interactions in the host environment are important in prognosis. These observations also suggest that a treatment paradigm shift from an exclusive focus on cell kill and specific tumor cell molecular targets to one focused also on broad host regulatory control may be useful. Clinical trials and laboratory mechanistic investigations based on these data and observations can determine the potential impact of therapeutic interventions targeting host system macro and micro tumor cell environments.

Fruits, Vegetables, and Micronutrients in Relation to Breast Cancer Modified by Menopause and Hormone Receptor Status

Whether fruit, vegetable, and antioxidant micronutrient consumption is associated with a reduction in breast cancer incidence remains unresolved. To address this issue, we analyzed data from a large population-based case-control study, with consideration given to whether the associations varied with menopausal status or with clinical characteristics of the cases' disease. Study participants completed a modified Block food frequency questionnaire, which included assessment of the frequency and portion sizes of 13 fruits and fruit juices and 16 vegetables and the use of multiple and single vitamin supplements. Statistical analyses were done on 1,463 cases and 1,500 controls. Among postmenopausal women, reduced odds ratios [OR; 95% confidence intervals (95% CI)] were noted for the highest fifth, as compared with the lowest fifth, of intake of any vegetables [0.63 (0.46–0.86); P for trend &lt; 0.01] and leafy vegetables [0.66 (0.50–0.86); P for trend = 0.03] after controlling for age and energy intake. Adjusted ORs (95% CIs) were also decreased for postmenopausal breast cancer in relation to high intake of carotenoids, α-carotene, β-carotene, lutein, and particularly lycopene [0.66 (0.48–0.90); P for trend = 0.03]. Inverse associations for fruits and vegetables were stronger for postmenopausal women with estrogen receptor (ER)+ tumors (OR, 0.65; 95% CI, 0.51–0.82) than ER− tumors (OR, 0.92; 95% CI, 0.64–1.32), but results were less consistent for micronutrients. No similarly reduced associations were observed among premenopausal women. ORs did not appreciably differ by in situ or invasive breast cancer or by whether cases had begun chemotherapy. Our results support an inverse association for fruit and vegetable intake among postmenopausal but not premenopausal breast cancer, which may be more pronounced among women with ER+ tumors.

Comparison of Age-Specific Incidence Rate Patterns for Different Histopathologic Types of Breast Carcinoma

Objective: The age-specific incidence rate curve for breast carcinoma overall increases rapidly until age 50 years, and then continues to increase at a slower rate for older women. In this analysis, our objective was to compare age-specific incidence rate patterns for different morphologic types of breast carcinoma. Materials and methods: We analyzed age-specific incidence rate curves by histopathologic subclassification using records from 11 standard National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registries, diagnosed during the years 1992 to 1999. Data were examined by age &lt;50 and ≥50 years to simulate menopause. Results: Age-specific incidence rate curves showed three dominant patterns: (1) Rates for infiltrating duct carcinoma of no special type (duct NST), tubular, and lobular carcinomas increased rapidly until age 50 years then rose more slowly. (2) Rates for medullary and inflammatory breast carcinomas increased rapidly until age 50 years then failed to increase. (3) Rates for papillary and mucinous carcinomas increased steadily at all ages. Rate patterns varied by estrogen receptor expression but were unaffected by SEER registry, race, nodal status, or grade. Conclusion: Age-specific incidence rates for breast carcinomas differed by histopathologic type. Rates that failed to increase after 50 years suggested that menopause had greater impact on medullary and inflammatory carcinomas than on duct NST, tubular, and lobular carcinomas. Menopause did not seem to have any effect on papillary or mucinous carcinomas as evidenced by steadily rising rates at all ages. Future etiologic and/or prevention studies should consider the impact of age-specific risk factors and/or exposures on different histopathologic types of breast carcinomas.

A prognostic index for operable, node-negative breast cancer

Clinical data and samples from patients diagnosed, more than 10 years previously, with operable node-negative breast cancer (participants in the Scottish Adjuvant Tamoxifen trial), were revisited. Cases with two distinct categories of outcome were selected; more than 10 years disease-free survival ('good outcome') or distant relapse within 6 years of diagnosis ('poor outcome'). An initial set of cases was analysed for a range of putative prognostic markers and a prognostic index, distinguishing the two outcome categories, was calculated. This index was then validated by testing its predictive power on a second, independent set of cases. A combination of histological grade plus immunochemical staining for BCL-2, p27 and Cyclin D1, generated a useful prognostic index for tamoxifen-treated patients but not for those treated by surgery alone. The value of the index was confirmed in a second set of tamoxifen-treated, early stage breast cancers. Overall, it correctly predicted good and poor outcome in 79 and 74% of cases, respectively (odds ratio 11.0). Other markers assessed added little to prediction of outcome. In the case of molecular assays, sensitivity and reliability were compromised by the age of the tissue specimens and the variability of fixation protocols. In selecting patients for adjuvant systemic chemotherapy, the proposed index improves considerably on current international guidelines and matches the performance reported for 'gene-expression signature' analysis.

Risk factors for breast cancer according to estrogen and progesterone receptor status

BACKGROUND

Evaluations of epidemiologic risk factors in relation to breast cancer classified jointly by estrogen receptor (ER) and progesterone receptor (PR) status have been inconsistent. To address this issue, we conducted a prospective evaluation of risk factors for breast cancer classified according to receptor status.

METHODS

During 1 029 414 person-years of follow-up of 66 145 women participating in the Nurses' Health Study from 1980 through 2000, we identified 2096 incident cases of breast cancer for which information on ER/PR status was available: 1281 were ER+/PR+, 318 were ER+/PR-, 80 were ER-/PR+, and 417 were ER-/PR-. We fit a log-incidence model of breast cancer and used polychotomous logistic regression to compare coefficients for breast cancer risk factors in patients with different ER/PR status. To test for differences in risk factor odds ratios based on marginal ER/PR categories, we evaluated ER status controlling for PR status and vice versa. The predictive ability of our log-incidence model to discriminate between women who would develop ER+/PR+ breast cancer and those who would not (and similarly for ER-/PR- breast cancer) was evaluated by using receiver operator characteristic curve analysis. All statistical tests were two-sided.

RESULTS

We observed statistically significant heterogeneity among the four ER/PR categories for some risk factors (age, menopausal status, body mass index [BMI] after menopause, the one-time adverse effect of first pregnancy, and past use of postmenopausal hormones) but not for others (benign breast disease, family history of breast cancer, alcohol use, and height). The one-time adverse association of first pregnancy with incidence was present for PR- but not for PR+ tumors after controlling for ER status (P =.007). However, the association of BMI after menopause with incidence was present for PR+ but not PR- tumors (P =.005). Statistically significant differences in the incidence of ER+ and ER- tumors were seen with age, both before and after menopause (P =.003), and with past use of postmenopausal hormones (P =.01). Area under the receiver operator characteristic curve, adjusted for age, was 0.64 (95% confidence interval [CI] = 0.63 to 0.66) for ER+/PR+ tumors and 0.61 (95% CI = 0.58 to 0.64) for ER-/PR- tumors.

CONCLUSIONS

Incidence rates and risk factors for breast cancer differ according to ER and PR status. Thus, to accurately estimate breast cancer risk, breast cancer cases should be divided according to the ER and PR status of the tumor.

Is Male Breast Cancer Similar or Different than Female Breast Cancer?

OBJECTIVE

To determine if male breast carcinogenesis was similar to its more common female counterpart, we compared incidence patterns among men and women with breast cancer.

METHODS

Breast cancer records were obtained from the SEER database. Women were stratified by age < 50 and > or = 50 years to simulate premenopausal and postmenopausal breast cancer.

RESULTS

Age-adjusted incidence trends were stable among men but increased among women. Male to female breast cancer ratio was higher for blacks than for whites. Favorable prognostic factors reflective of tumor biology (nuclear grade and hormone receptor expression) were more common for men and postmenopausal women than for premenopausal women. For example, low nuclear grade, estrogen and progesterone receptor-positive expression were more common among men and postmenopausal women than among premenopausal women. The age-specific incidence rate curve for men increased steadily for all ages with a constant slope. On the other hand, age-specific rates for women increased rapidly until age 50 years then rose at a slower rate for postmenopausal women. Age-frequency distribution for male breast cancer was unimodal, with peak incidence at age 71 years. Age-frequency distribution for women was bimodal with early-onset and late-onset incidence at 52 and 71 years, respectively.

CONCLUSIONS

Gender-specific incidence trends differed, most likely reflective of female-related changes in surveillance and/or reproductive risk factors. On the other hand, similar prognostic factor profiles reflective of tumor biology, age-specific incidence rate patterns, and age-frequency distributions suggested that male breast cancer was more like postmenopausal than premenopausal female breast cancer.

Risk factors for breast cancer in young women by oestrogen receptor and progesterone receptor status

We used data from 765 cases and 564 controls in the population-based Australian Breast Cancer Family Study to investigate whether, in women under the age of 40, the profile of risk factors differed between breast cancer subtypes defined by joint oestrogen and progesterone receptor status. As hypothesised, no significant differences were found.

Electric Blanket Use and Breast Cancer on Long Island

BACKGROUND

Exposure to electromagnetic fields (EMF) has been hypothesized to increase the risk of breast cancer by inhibiting the normal nocturnal rise in melatonin levels.

METHODS

Information on electric blanket use was collected in a large, 2-stage, population-based, case-control investigation of breast cancer, The Long Island Breast Cancer Study Project (LIBCSP) and the EMF and Breast Cancer on Long Island Study (EBCLIS). The LIBCSP used a comprehensive questionnaire, including questions about electric appliance use, with responses available on 1354 cases diagnosed between mid-1996 and mid-1997 and 1426 control subjects. EBCLIS enrolled 576 cases and 585 control subjects who had participated in the LIBCSP and who had lived in their current homes for at least 15 years. EBCLIS participants were interviewed to obtain additional information on EMF exposures, including detailed questions on electric blanket use.

RESULTS

Analyses of both the EBCLIS and the LIBCSP groups showed no association with breast cancer for ever-use of electric blankets, current or former use, use directly on the body, or use throughout the night in either pre- or postmenopausal women (range of adjusted odds ratios for ever vs. never use: 0.9-1.2). Furthermore, there was no trend in risk with increased duration of use, frequency of use, or other indicators of more intense exposure to EMF. Electric blanket use was not associated with hormone receptor status of the tumor.

CONCLUSIONS

The results of this large investigation are consistent with those of most previous studies, and do not support the hypothesis that electric blanket use is associated with increased breast cancer risk.

Inflammatory breast carcinoma and noninflammatory locally advanced breast carcinoma: distinct clinicopathologic entities?

PURPOSE

Inflammatory breast carcinoma (IBC) and noninflammatory locally advanced breast carcinoma (LABC) are both associated with poor prognosis; however, whether they are distinct clinicopathologic entities remains controversial.

MATERIALS AND METHODS

To determine whether IBC and LABC were different, we compared tumor characteristics, prognosis, and age-specific incidence rate patterns in the Surveillance, Epidemiology, and End-Results program. An age of 50 years served as a surrogate marker for menopause.

RESULTS

Younger age at diagnosis, poorer tumor grade, and negative estrogen receptors (ERs) were more predictive of IBC (n = 2,237) than of LABC (n = 7,985). Breast carcinoma survival was worse for patients with IBC than for those with LABC (log-rank test, P <.0001). Age-specific incidence rates for IBC increased until 50 years and then flattened, whereas rates for LABC increased for all ages. When rates for LABC were stratified by estrogen receptor-positive (ERP) and -negative (ERN) expression, rates for ERP and ERN diverged; that is, rates for ERP increased with advancing age, whereas rates for ERN flattened after 50 years. When rates for IBC were stratified by ER expression, rates for both ERP and ERN flattened after 50 years of age.

CONCLUSION

IBC and LABC seemed to be distinct biologic entities, as indicated by different prognostic factor profiles and age-specific incidence rate patterns. Rates that increased before 50 years and then stabilized, possibly indicated that premenopausal exposures had a greater effect on maintaining rates for IBC than for LABC.

New insights into estrogen receptor function in human breast cancer

An important new concept associated with estrogen receptor (ER) function in breast cancer is that ER status/ phenotype is multifaceted. In particular, the two full-length, ligand binding ERs (ER-alpha and ER-beta) and possibly multiple variant isoforms of ER must be considered. In addition, cross-talk factors that can influence ER activity in a ligand independent fashion and factors downstream of the ER, including coactivators and corepressors, clearly have important roles in ER function. Their careful evaluation in addition to ER status will be necessary to more fully understand the etiology of breast cancer and the changes occurring in estrogen signaling during breast tumorigenesis and breast cancer progression. Such knowledge is necessary to have a significant impact on better prevention and treatment strategies for human breast cancer.

Incidence of invasive breast cancer by hormone receptor status from 1992 to 1998

PURPOSE

Between 1987 and 1998, breast cancer incidence rates rose 0.5%/yr in the United States. A question of potential etiologic and clinical importance is whether the hormone receptor status of breast tumors is also changing over time. This is because hormone receptor status may reflect different etiologic pathways and is useful in predicting response to adjuvant therapy and prognosis.

METHODS

Age-adjusted, age-specific breast cancer incidence rates by estrogen receptor (ER) and progesterone receptor (PR) status from 1992 to 1998 were obtained and compared from 11 population-based cancer registries in the United States that participate in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program.

RESULTS

From 1992 to 1998, the overall proportion of breast cancers that were ER-positive and PR-positive increased from 75.4% to 77.5% (P =.0002) and from 65.0% to 67.7% (P <.0001), respectively, continuing trends observed before 1992. These increases were limited to women 40 to 69 years of age. The proportions of ER-positive/PR-positive tumors increased from 56.7% to 62.3% (P =.0010) among 40- to 49-year-olds, from 58.0% to 63.2% (P =.0002) among 50- to 59-year-olds, and from 63.2% to 67.9% (P =.0020) among 60- to 69-year-olds.

CONCLUSION

From 1992 to 1998, the proportion of tumors that are hormone receptor-positive rose as the proportion of hormone receptor-negative tumors declined. Because the incidence rates of hormone receptor-negative tumors remained fairly constant over these years, the overall rise in breast cancer incidence rates in the United States seems to be primarily a result of the increase in the incidence of hormone receptor-positive tumors. Hormonal factors may account for this trend.

Age-dependent changes in breast cancer hormone receptors and oxidant stress markers

Breast cancer incidence increases with age but this relationship has not been fully explored with regard to expression of estrogen receptor (ER) and ER-inducible genes (PR, pS2, Bcl2, cathepsin D), or the age-dependence of oxidant stress markers that also affect ER-inducible gene expression. In this three-part study, we first correlated age at diagnosis with expression of breast cancer markers ER, PR, pS2, Bcl2, and cathepsin D, quantitated by enzyme immunoassays from a European collective of approximately 3000 cryobanked primary breast cancers and approximately 300 adjacent non-malignant breast tissues. Results were then compared with ER and PR data reported to the SEER registry for 83,541 US cancers diagnosed during 1992-1997. Lastly, a homogeneous subset of 70 ER-positive tumors preselected from the European collective was blindly analyzed for age-specific changes in the DNA-binding content of redox-sensitive transcriprtion factors, AP1 and Sp1, and the oxidant stress-activated protein kinase, phosphorylated(P)-Erk5. Increases in breast tumor ER from patients aged <30 to >80 years mirrored 10-fold lower increases in non-malignant breast tissue ER content up to age 60, rising faster thereafter and reaching a near 25-fold differential between malignant and non-malignant breast tissue by age 80. ER-inducible markers PR, pS2, Bcl2, and cathepsin D were overexpressed in tumors relative to non-malignant breast tissue but, unlike ER, did not increase with patient age. While SEER data demonstrated that the increase in US breast cancer incidence rates after age 50 is confined to ER-positive tumors in patients of all ethnic subsets, these patients also showed a striking increase in the proportion of higher-risk ER-positive/PR-negative breast cancers arising after age 50. Mechanistically essential for ER-inducible PR expression, Sp1 DNA-binding function (but not Sp1 content) was lost with age in ER-positive tumors; and this functional defect correlated with increased tumor content of the oxidant stress marker, P-Erk5. Altogether these findings support two hypotheses: (i) dysregulated ER expression underlies the age-specific increase in breast cancer incidence after age 50; and (ii) oxidative stress and loss of Sp1 DNA-binding may contribute to an increasing incidence in higher-risk ER-positive/PR-negative breast cancers with aging.

Estrogen receptor breast cancer phenotypes in the Surveillance, Epidemiology, and End Results database

BACKGROUND

Researchers question whether estrogen receptor alpha-negative (ERN) and -positive (ERP) represent different stages of one disease or different breast cancer types.

OBJECTIVE

To further examine ERalpha phenotypes, we stratified incident tumor characteristics in the Surveillance, Epidemiology, and End Results (SEER) Database (n = 82,488) by ERN and ERP.

METHODS

Study variables included black-white race, age-at-diagnosis, and standard incident tumor characteristics. These characteristics were arbitrarily dichotomized into good versus poor prognostic factor groups, for example, good (tumor size < or = 2.0 cm, negative axillary lymph nodes, and good histologic grade) versus poor (tumor size > 2.0 cm, positive nodes, and poor grade). Age frequency density plots were generated from the corresponding age-at-diagnosis frequency histograms. Average annual age-specific incidence rates (or risks) were adjusted to the 1970 United States standard female population.

RESULTS

Age frequency density plots demonstrated bimodal premenopausal and postmenopausal breast cancer populations. ERN was correlated with premenopausal disease, black race, and poor prognostic factor groups, whereas ERP was associated with postmenopausal disease, white race, and favorable tumor characteristics. ERN rates increased premenopausally and then flattened to a nearly constant level after 50 years of age. ERP risk rose for most of a woman's lifetime with the greatest risk occurring between 75 and 79 years.

CONCLUSIONS

ERalpha exhibited bimodal age frequency distribution with a dichotomous pattern for age-specific rates, racial, and prognostic factor profiles. Menopause had a greater effect on ERN than ERP. Possible implications for breast carcinogenesis and cancer prevention are discussed in the text.

Rates for breast cancer characteristics by estrogen and progesterone receptor status in the major racial/ethnic groups

It has been reported that age-specific breast cancer rates vary by estrogen receptor and progesterone receptor status. We report breast cancer rates for age-at-diagnosis, stage-at-diagnosis, histological grade and type by estrogen (ER) and progesterone (PgR) receptor status in six major racial/ethnic groups. The average annual age-adjusted rates for breast cancers with estrogen receptor positive (ER+), ER-, progesterone receptor positive (PgR+), PgR-, ER+PgR+, ER+PgR-, ER-PgR+ and ER-PgR- are determined from 123,732 breast cancers with known ER status, diagnosed from 1992 to 1998 from 11 Surveillance, Epidemiology, and End Results (SEER) cancer registries. For each racial/ethnic group, their ER+ (ER+PgR+ and ER+PgR-) age-specific rates increased with age (but at a slower pace after ages 50-54) while their ER- (ER- PgR+ and ER-PgR-) age-specific rates did not increase after ages 50-54. The rank orders of the rates among the racial/ethnic groups varied by ER/PgR status. The stage I rates were greater than the stage II rates for the ER/PgR groups except for ER- and ER- PgR- cancers. The grade 2 (moderately differentiated) rates were greater than the grades 3 and 4 (poorly differentiated and undifferentiated cancers) rates for ER+ cancers, but not for ER- cancers. These results suggest that although breast cancer is a disease with enormous heterogeneity, the multiple types of breast cancer can be separated into distinct subgroups by their ER status, and perhaps by their ER/PgR status, and their cancer characteristics may be important in understanding the multiple nature of breast cancer.

Role of dopamine in malignant tumor growth

The regulatory role of dopamine, a monoamine neurotransmitter and/or a neurohormone in controlling the secretion of several anterior pituitary hormones, cardiovascular, and renal functions, has already been extensively used by clinicians for therapeutic purposes. In addition to these important functions of dopamine, some recent reports also indicate its novel role in regulating malignant cell proliferation and controlling immune functions in tumor-bearing animals. Therefore, in this article, we discuss all the relevant information correlating dopamine and malignant tumor growth in order to understand the host-tumor relationship at the level of a neurotransmitter and/or a neurohormone.