Use of menopausal hormone therapy and risk of ductal and lobular breast cancer among women 55-74 years of age

The Challenges of Lobular Carcinomas from a Surgeon's Point of View

Invasive lobular breast cancer (ILC) presents unique challenges and considerations in the realm of surgical management. Characterized by its distinct histological features, including the loss of E-cadherin expression and dys-cohesive growth pattern, ILC often poses diagnostic and therapeutic dilemmas for clinicians. This abstract explores the surgical landscape of ILC, focusing on its epidemiology, clinical presentation, diagnostic modalities, and surgical interventions. Emphasizing the importance of individualized treatment strategies, this narrative delves into the nuances of surgical decision-making, including the role of breast-conserving surgery versus mastectomy, axillary staging, and the significance of margin status. Additionally, advancements in surgical techniques, such as oncoplastic approaches and sentinel lymph node biopsy, are examined in the context of optimizing oncologic outcomes and preserving cosmesis. Through a comprehensive review of current literature and clinical guidelines, this overview aims to provide a nuanced understanding of the surgical considerations inherent to the management of invasive lobular breast cancer.

Is There a Special Role for Ovarian Hormones in the Pathogenesis of Lobular Carcinoma?

Lobular carcinoma represent the most common special histological subtype of breast cancer, with the majority classed as hormone receptor positive. Rates of invasive lobular carcinoma in postmenopausal women have been seen to increase globally, while other hormone receptor-positive breast cancers proportionally have not followed the same trend. This has been linked to exposure to exogenous ovarian hormones such as hormone replacement therapy. Reproductive factors resulting in increased lifetime exposure to endogenous ovarian hormones have also been linked to an increased risk of lobular breast cancer, and taken together, these data make a case for the role of ovarian hormones in the genesis and progression of the disease. In this review, we summarize current understanding of the epidemiological associations between ovarian hormones and lobular breast cancer and highlight mechanistic links that may underpin the etiology and biology.

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.

Multivariate analysis of independent roles of socioeconomic status, occupational physical activity, reproductive factors, and postmenopausal hormonal therapy in risk of breast cancer

PURPOSE

This case-control study assesses the independent roles of reproductive history, postmenopausal hormonal therapy (HT), socioeconomic status (SES), and occupational physical activity on the risk of breast cancer (BC).

METHODS

Odds ratios (OR) were estimated from conditional logistic multivariate regression model in a data set of 19,253 Finnish women diagnosed with BC between 1994 and 2013 and 96,265 age-matched population controls.

RESULTS

Both pre- and postmenopausal white-collar workers had significantly increased risk of ductal and lobular BC as compared to manual workers. Moderate occupational physical activity reduced risk of lobular BC by 14%. There was a transient increase in the risk of BC observed after each birth followed by a protective effect starting some years after the delivery. As the number of children increased, the short-term excess risk was lower and protective effect was observed earlier. Continuous estrogen-progestin therapy (EPT) significantly increased the risk of both ductal and lobular BC and the magnitude of risk was directly proportional to duration of use (OR for 5+ years of use 2.26, 95% confidence interval 2.12-2.42). Monthly EPT for 5+ years increased the risk (OR 1.32, 95% CI 1.20-1.45). Users of estradiol plus levonorgestrel intrauterine system devices showed ORs of 1.56 (95% CI 1.45-1.69) and 2.18 (95% CI 1.81-2.64) for ductal and lobular BC, respectively.

CONCLUSION

This study concludes that pregnancy has a dual effect on BC risk, with a transient increase in risk followed by a long-term protective effect. The SES and HT have a large effect on BC risk while occupational physical activity has only a small independent effect.

Causes of death among women with breast cancer: A follow-up study of 50 481 women with breast cancer in Finland

Our study aims to assess mortality from causes other than breast cancer among women with breast cancer with focus on indications of joint aetiology. Data on female breast cancer patients were obtained from the Finnish Cancer Registry and their underlying causes of death in 54 categories from the Statistics Finland. Standardised mortality ratios (SMR) and their 95% confidence intervals (CIs) were calculated for 50 481 patients diagnosed between 1971 and 2000 and followed until December 2012, stratified by histology, age at diagnosis and time since diagnosis. The expected numbers of deaths were based on respective mortality rates among the Finnish general population. Hazard ratio (HR) was estimated from Poisson regression model to compare risks of cause of death by histology. 41% of 30 841 deaths were due to causes other than breast cancer. Significant excess mortality was observed for stomach cancer (SMR 1.43, 95% CI 1.26-1.62), circulatory system diseases (SMR 1.17, 95% CI 1.14-1.20) and suicide (SMR 1.51, 95% CI 1.28-1.78). In an age-adjusted analysis, significantly higher relative risk of stomach cancer mortality was observed for lobular vs ductal subtype (HR 2.00, 95% CI 1.32-3.02). Significantly increased SMRs were observed for cancers of respiratory organs among premenopausal women, and for other respiratory system diseases, dementia and Alzheimer disease among postmenopausal women. We conclude that female breast cancer patients are at increased risk of death from causes other than the breast cancer diagnosis including circulatory and respiratory system diseases and cancer of stomach, ovary and respiratory systems. The excess mortality because of different causes varies based on menopausal status and histology. There might be shared aetiological factors between the diagnosis of breast cancer and the causes of death among these patients.

Self-selection for mammography screening according to use of hormone replacement therapy: A systematic literature review

Mammography screening participation may be influenced by the awareness of an increase in breast cancer risk due to hormone replacement therapy (HRT), which received particular attention upon publication of the Women's Health Initiative (WHI) trial results in 2002. Our aim was to synthesize evidence on a potential self-selection for mammography screening according to HRT use. We systematically searched the literature (MEDLINE, EMBASE, CINAHL) for studies reporting on the association between HRT use and mammography screening participation. Data were extracted independently by two reviewers. Overall, 2018 studies were identified. Of these, 32 studies from nine countries, predominantly from North America (50%) and Europe (28%), were included. In studies from all countries and 94% of all studies, higher mammography screening uptake among HRT users compared to non-users was reported. In all 21 studies reporting an odds ratio, the association was positive, and in about 70% of these studies, this association was ≥2. This also held true for studies exclusively using data collected before publication of the WHI findings in 2002 (63% of all studies). The association was not restricted to certain types of screening (organized vs. opportunistic) or certain types of HRT (combined vs. estrogen-only). We found a consistent and relevant association between mammography screening uptake and HRT use. This is of considerable relevance for the design and interpretation of studies investigating risk factors or evaluating preventive measures for breast cancer.

Imaging of Breast Cancers With Predilection for Nonmass Pattern of Growth: Invasive Lobular Carcinoma and DCIS-Does Imaging Capture It All?

OBJECTIVE. Invasive lobular carcinoma (ILC) and ductal carcinoma in situ (DCIS) are distinct histopathologic entities with several commonalities: both have subtle clinical and imaging presentation, have been linked with controversy regarding optimal imaging techniques and management, and exemplify the codependence of adequate imaging evaluation and optimal treatment strategies in breast care. CONCLUSION. We review molecular mechanisms and histopathologic patterns that define the biologic behavior of both ILC and DCIS and discuss how these mechanisms translate into distinct clinical and imaging presentations that affect the staging workup and patient management algorithm.

Is There Etiologic Heterogeneity between Subtypes of Childhood Acute Lymphoblastic Leukemia? A Review of Variation in Risk by Subtype

Although substantial advances in the identification of cytogenomic subtypes of childhood acute lymphoblastic leukemia (ALL) have been made in recent decades, epidemiologic research characterizing the etiologic heterogeneity of ALL by subtype has not kept pace. The purpose of this review is to summarize the current literature concerning subtype-specific epidemiologic risk factor associations with ALL subtype defined by immunophenotype (e.g., B-cell vs. T-cell) and cytogenomics (including gross chromosomal events characterized by recurring numerical and structural abnormalities, along with cryptic balanced rearrangements, and focal gene deletions). In case-control analyses investigating nongenetic risk factors, home paint exposure is associated with hyperdiploid, MLL-rearranged, and ETV6-RUNX1 subtypes, yet there are few differences in risk factor associations between T- and B-ALL. Although the association between maternal smoking and ALL overall has been null, maternal smoking is associated with an increasing number of gene deletions among cases. GWAS-identified variants in ARID5B have been the most extensively studied and are strongly associated with hyperdiploid B-ALL. GATA3 single nucleotide variant rs3824662 shows a strong association with Ph-like ALL (OR = 3.14). However, there have been relatively few population-based studies of adequate sample size to uncover risk factors that may define etiologic heterogeneity between and within the currently defined cytogenomic ALL subtypes.

Low risk of invasive lobular carcinoma of the breast in carriers of BRCA1 (hereditary breast and ovarian cancer) and TP53 (Li-Fraumeni syndrome) germline mutations

BACKGROUND

Invasive lobular carcinoma (ILC) of the breast has epidemiological, molecular and clinical specificities, and should likely be considered a unique entity. As for genetic susceptibility, CDH1 germline mutations predispose exclusively to ILC. Data are however scarce regarding ILC in women with BRCA1/2 (Hereditary Breast and Ovarian Cancer) and TP53 (Li-Fraumeni syndrome) germline mutations.

METHODS

We included all breast cancers from female patients tested at our institute between 1992 and 2016 (n = 3469) for which pathology data were available. ILC proportion comparison according to mutational status was performed by a chi-squared test. The impact of susceptibility genes on ILC proportion was investigated by univariate logistic regression with wild-type patients as reference.

RESULTS AND DISCUSSION

There were 265 (7.64%) ILC: 2/342 (0.58%) in BRCA1 patients, 24/238 (10%) in BRCA2 patients, 1/57 (1.75%) in TP53 patients and 238/2832 (8.4%) in non-carriers. The majority of breast cancers in all groups were invasive ductal and ductal in situ carcinomas. The difference in ILC proportion was highly significant (P < 0.001). Compared to wild-type patients, BRCA1 was associated with a lower ILC proportion (OR 0.064 [95% CI 0.016;0.259], P < 0.0001). BRCA2 OR was 1.222 [95%CI 0.785;1.902] (P = 0.374), TP53 OR was 0.195 [95%CI 0.027;1.412] (P = 0.105). ILC are therefore underrepresented in BRCA1 and TP53 mutation carriers. Formal significance (P = 0.05) was not reached for TP53, but statistical power was only 38%. Based on ILC incidence in the general population, we make the hypothesis that BRCA1 and TP53 do not predispose to ILC, as the few occurrences of ILC in mutation carriers could be attributed to chance and not to germline mutations. Our observations will be useful to clinical cancer geneticists managing patients with ILC, as a BRCA1 or TP53 mutation in these patients would be unlikely. Genetic counseling should be adapted accordingly.

Polyfluorinated iodine alkanes regulated distinct breast cancer cell progression through binding with estrogen receptor alpha or beta isoforms

Polyfluorinated iodine alkanes (PFIs) are a kind of emerging chemicals with endocrine disrupting effects. Based on the different binding preferences of PFIs to estrogen receptor alpha and beta isoforms (ERα and β), two representative PFIs, dodecafluoro-1,6-diiodohexane (PFHxDI) and tridecafluorohexyl iodide (PFHxI), were selected to evaluate their effects on the proliferation of two kinds of breast cancer cells with different ERα/β expression levels, MCF-7 and T47D. The cell viability assay showed PFHxDI could cause higher cellular toxicity than did PFHxI in both MCF-7 and T47D. MCF-7 with relatively higher ERα/β expression ratio was more vulnerable to the cytotoxic treatments of PFHxI and PFHxDI when compared with T47D cells with relatively lower ERα/β expression ratio. EdU incorporation and cell cycle analysis revealed that, similar to 17β-estrodiol (E₂), non-cytotoxic levels of PFHxDI could significantly promote the proliferation of MCF-7 by increasing cell population at S phase (p < 0.01), while T47D proliferation was not influenced by PFHxI exposure due to cell cycle arrest at G2/M phase. The cellular responses caused by estrogenic PFIs were dominantly mediated by their preferential binding affinities for ER isoforms, which would be helpful in the accurate assessment for their potential influences on the breast cancer progression.

Reproductive risk factor associations with lobular and ductal carcinoma in the Carolina Breast Cancer Study

BACKGROUND

Invasive lobular breast tumors display unique reproductive risk factor profiles. Lobular tumors are predominantly Luminal A subtype, and it is unclear whether reported risk factor associations are independent of molecular subtype.

METHODS

Polytomous logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) for the associations between risk factors and histologic subtype [ductal (n = 2,856), lobular (n = 326), and mixed ductal-lobular (n = 473)] in the Carolina Breast Cancer Study (1993-2013). Three-marker immunohistochemical clinical subtypes were defined as Luminal A (ER+ or PR+/HER2-), Luminal B (ER+ or PR+/HER2+), Triple Negative (ER-/PR-/HER2-), and HER2+ (ER-/PR-/HER2+).

RESULTS

In case-case analyses compared to ductal, lobular tumors were significantly associated with lactation duration > 12 months [OR 1.86, 95% CI (1.33-2.60)], age at first birth ≥ 26 years [OR: 1.35, 95% CI: (1.03-1.78)], and current oral contraceptive use [OR: 1.86, 95% CI: (1.08-3.20)]. Differences in risk factor associations between ductal and lobular tumors persisted after restricting to Luminal A subtype.

CONCLUSIONS

Lobular tumors were associated with older age at first birth, increased lactation duration, and current oral contraceptive use. Etiologic heterogeneity by histology persisted after restricting to Luminal A subtype, suggesting both tumor histology and intrinsic subtype play integral parts in breast cancer risk.

Clinicopathological characteristics and survival outcomes of invasive lobular carcinoma in different races

To investigate the clinicopathological characteristics and to determine whether there is a differential effect of race and examine survival outcomes according to race, 18,295 breast invasive lobular carcinoma (ILC) patients were identified in the Surveillance, Epidemiology, and End Result (SEER) database, which includes White patients (n=15,936), Black patients (n=1,451) and patients of other races (including American Indians/Alaskan Natives and Asian/Pacific Islanders) (n=908). The Black ILC patients presented a higher rate of advanced histological grades and American Joint Committee on Cancer (AJCC) stages, a higher rate of lymph node (LN) involvement and a lower rate of progesterone receptors (PR)-positivity than the White patients and other races. The five-year overall survival (OS) and five-year breast cancer specific survival (BCSS) were worst in the Black patients among these patients (85.5%, 76.0% and 87.7%, P<0.01; 91.1%, 84.4% and 91.6%, P<0.01). Multivariate regression analyses were performed to determine the risk hazards ratios (HR) of death for patients of the White, Black and other races. Among these patients, the Black patients had the worst survival outcomes in five-year OS and BCSS outcomes (HR=1.35, 95% confidence interval (CI) :1.20-1.51, P<0.01; HR=1.39, 95%CI:1.21-1.61, P<0.01, respectively). After a 1:1:1 matching of the three groups, the Black patients still presented worse survival outcomes in BCSS compared to White patients (HR=1.88, 95%CI: 1.14-3.10, P=0.013), however, there was no difference in OS (HR=1.35, 95%CI: 0.93-1.96, P=0.111). Difference in outcomes may partially explained by difference in histological grades, AJCC stage, LN and PR status among the three groups. In conclusion, this study revealed that the Black patients had worse five-year OS and BCSS than White and other race patients.

Distinct Pattern of Metastases in Patients with Invasive Lobular Carcinoma of the Breast

BACKGROUND

Invasive lobular carcinoma (ILC) comprises around 10 - 15% of invasive breast cancers. Few prior studies have demonstrated a unique pattern of metastases between ILC and the more common invasive ductal carcinoma (IDC). To our knowledge, such data is limited to first sites of distant recurrence. We aimed to perform a comparison of the metastatic pattern of ILC and IDC at first distant recurrence as well as over the entire course of metastatic disease.

METHODS

We used a prospectively collated database of patients with metastatic breast cancer. Breast cancer recurrence or metastases were classified into various sites and a descriptive analysis was performed.

RESULTS

Among 761 patients, 88 (11.6%) were diagnosed with ILC and 673 (88.4%) with IDC. Patients with ILC showed more frequent metastases to the bone (56.8 vs. 37.7%, p = 0.001) and gastrointestinal (GI) tract (5.7 vs. 0.3%, p < 0.001) as first site of distant recurrence, and less to organs such as lung (5.7 vs. 24.2%, p < 0.001) and liver (4.6 vs. 11.4%, p = 0.049). Over the entire course of metastatic disease, more patients with ILC had ovarian (5.7 vs. 2.1%, p = 0.042) and GI tract metastases (8.0 vs. 0.6%, p < 0.001), also demonstrating reduced tendency to metastasize to the liver (20.5 vs. 49.0%, p < 0.001) and lung (23.9 vs. 51.9%, p < 0.001). All associations but bone held after sensitivity analysis on hormonal status. Although patients presenting with ILC were noted to have more advanced stage at presentation, recurrence-free survival in these patients was increased (4.8 years vs. 3.2 years, p = 0.017). However, overall survival was not (2.5 vs. 2.0 years, p = 0.75).

CONCLUSION

After accounting for hormone receptor status, patients with IDC had greater lung/pleura and liver involvement, while patients with ILC had a greater propensity to develop ovarian and GI metastases both at first site and overall. Clinicians can use this information to provide more directed screening for metastases; it also adds to the argument that these two variants of breast cancer should be managed as unique diseases.

Alcohol Intake and Risk of Breast Cancer by Histologic Subtype and Estrogen Receptor Status Among Women Aged 55 to 74 Years

Previous studies suggest that alcohol consumption and risk of breast cancer may differ by histologic subtype and hormone receptor status, though results are not entirely consistent. In this population-based case-control study, we evaluated the association between alcohol consumption and risk of invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC), and invasive ductal-lobular carcinoma (IDLC) overall and by estrogen receptor (ER) status, among women aged 55-74 years of age. Using polytomous regression, associations between current alcohol consumption, overall and by type of alcohol, and breast cancer risk were evaluated in 891 controls and 905 IDC, 567 ILC, and 489 IDLC cases. Current alcohol use was moderately associated with risk of ILC (odds ratio = 1.25, 95% confidence interval 0.99, 1.58) with a positive dose-response relationship based on average number of drinks per week consumed (P _trend = 0.0005). When further stratified by ER status, alcohol use was positively associated with risk of ER+ ILC (P _trend = 0.002) and ER+ IDC (P _trend = 0.02), but inversely associated with risk of ER-IDC (P _trend = 0.01). No association between alcohol and risk of IDLC tumors was observed. While the link between alcohol consumption and breast cancer risk is well established, our results suggest that the increased risk associated with alcohol is largely limited to ER+ ILC and ER+ IDC. Thus, avoiding or moderating alcohol consumption may be one way that women can lower their risks of these forms of breast cancer.

Postmenopausal Hormone Therapy and Breast Cancer Prognostic Characteristics: A Linkage between Nationwide Registries

BACKGROUND

The effects of use of different types of hormone therapy on breast cancer risk according to prognostic factors are largely unknown.

METHODS

We linked data from the Norwegian Prescription Database and the Cancer Registry of Norway during 2004 to 2009 on all women ages 45 to 79 years (N = 686,614). We estimated rate ratios and 95% confidence intervals for breast cancer in relation to hormone therapy using Poisson regression.

RESULTS

During an average 4.8 years of follow-up, 7,910 invasive breast cancers were diagnosed. Compared with nonusers of hormone therapy, users of estradiol and tibolone were more likely to be diagnosed with grade I, lymph node-negative, and estrogen receptor-positive (ER⁺)/progesterone receptor-positive (PR⁺) tumors. However, compared with nonusers, users of the most common estrogen and progestin combinations [estradiol-norethisterone acetate (NETA) preparations (Kliogest, Activelle or Trisekvens)] were at a 4- to 5-fold elevated risk of grade I tumors, 3-fold elevated risk of lymph node-negative tumors, and 3- to 4-fold elevated risk of ER⁺/PR⁺ tumors. Importantly, estradiol-NETA users were also at a 2- to 3-fold increased risk of medium differentiated (grade II) tumors and tumors with lymph node involvement.

CONCLUSIONS

Use of oral estradiol, tibolone, and estradiol-NETA predominantly increases the risk of breast cancer with favorable prognosis characteristics. However, use of estradiol-NETA preparations also increases the risk of breast cancers with less favorable characteristics.

IMPACT

The hormone therapy preparations most commonly used in the Nordic countries are associated with both breast cancers with good and less favorable prognosis characteristics. Cancer Epidemiol Biomarkers Prev; 25(11); 1464-73. ©2016 AACR.

Cancer statistics: Breast cancer in situ

An estimated 60,290 new cases of breast carcinoma in situ are expected to be diagnosed in 2015, and approximately 1 in 33 women is likely to receive an in situ breast cancer diagnosis in her lifetime. Although in situ breast cancers are relatively common, their clinical significance and optimal treatment are topics of uncertainty and concern for both patients and clinicians. In this article, the American Cancer Society provides information about occurrence and treatment patterns for the 2 major subtypes of in situ breast cancer in the United States-ductal carcinoma in situ and lobular carcinoma in situ-using data from the North American Association of Central Cancer Registries and the 13 oldest Surveillance, Epidemiology, and End Results registries. The authors also present an overview of in situ breast cancer detection, treatment, risk factors, and prevention and discuss research needs and initiatives.

The Urban/Rural Dichotomy in the Distribution of Breast Cancer across Pennsylvania

Breast cancer rates clearly differ across the United States. This is due to a variety of factors, but at least one determinant is the population density. Breast cancer detection rates and treatment paradigms may differ in rural areas when compared with more urban ones. As the population becomes more mobile and diffuse, this may or may not be a worsening problem. The current analysis was undertaken to examine the breast cancer incidence and outcomes in a single state in an attempt to plan for resource allocation in the future. A retrospective analysis was performed using data available from the Pennsylvania Department of Health regarding breast cancer rates by county, the distribution of cases with regard to degree of rurality, death rates by county as a function of rurality, and the age distribution of all presenting cases. Data from 1999 were compared with those of 2009. The United States Census Bureau definition of rurality was used, which specifies that a county be classified as rural if the population density is less than 284 persons/square mile. Between 1999 and 2009, the population of Pennsylvania increased by approximately 3.4 per cent (421,325 people). The urban population increased by 3.9 per cent, whereas the rural population increased by only 2.2 per cent. During that same period, the number of cancer cases/100,000 population remained about the same: 391.41 in 1999; 390.7 in 2009. However, the distribution of cases shifted during that time toward more rural areas of the state: in 1999, there were 372.3 breast cancer cases/100,000 population compared with 2009 when the rate was 384.4/100,000 population. The number of cancer deaths/100,000 population actually dropped overall during the decade: 98.5 in 1999 versus 82.3 in 2009. Though this was true in both urban and rural counties, the decrease was much less pronounced in the rural areas. In urban counties, the death rate dropped from 100.5 to 81.5/100,000 population, whereas in rural counties, the drop was only from 93.3 to 84.3. The greater increase in cases diagnosed in rural areas of Pennsylvania is only partially explained by the relatively greater increase in rural population. There are undoubtedly other issues at work in rural areas: environmental factors, diffusion of resources, less access to surveillance programs. In addition, though the death rate has dropped in both rural and urban areas, this is much less pronounced in rural counties. Coupled with the increase in prevalence in those areas, this suggests that breast cancer care may be lagging in rural areas. There is a need to examine allocation of resources and surveillance programs.

Breast cancer incidence and menopausal hormone therapy in Norway from 2004 to 2009: a register-based cohort study

In Norway, the breast cancer incidence increased by 50% in the 1990s, during a period with initiation of mammography screening as well as a fourfold increase in use of menopausal hormone therapy (HT). After 2002, the HT use has dropped substantially; however, the breast cancer incidence has declined only marginally. How much mammography screening contributed to the breast cancer incidence increase in the 1990s compared with HT use and specifically different types of HT use, has thus been discussed. Whether HT affects the incidence of subtypes of breast cancer differently has also been questioned. We have linked individual data from several national registries from 2004 to 2009 on 449,717 women aged 50–65 years. 4597 cases of invasive cancer and 681 cases of ductal carcinoma in situ (DCIS) were included in the analysis. We used Cox regression to estimate hazard ratio (HR) as a measure of the relative risk of breast cancer associated with use of HT. The HRs associated with prescriptions of HT for more than 1 year were 2.06 (1.90–2.24) for estrogen and progesterone combinations, 1.03 (0.85–1.25) for systemic estrogens, and 1.23 (1.01–1.51) for tibolone. Invasive lobular carcinoma was more strongly associated with use of estrogen and progesterone combinations, HR = 3.10 (2.51–3.81), than nonlobular carcinoma, HR = 1.94 (1.78–2.12). The corresponding value for DCIS was 1.61 (1.28–2.02). We estimated the population attributable fraction to 8.2%, corresponding to 90 breast cancer cases in 2006 indicating that HT use still caused a major number of breast cancer cases.

Lobular breast cancer: incidence and genetic and non-genetic risk factors

While most invasive breast cancers consist of carcinomas of the ductal type, about 10% are invasive lobular carcinomas. Invasive lobular and ductal carcinomas differ with respect to risk factors. Invasive lobular carcinoma is more strongly associated with exposure to female hormones, and therefore its incidence is more subject to variation. This is illustrated by US figures during the 1987 to 2004 period: after 12 years of increases, breast cancer incidence declined steadily from 1999 to 2004, reflecting among other causes the decreasing use of menopausal hormone therapy, and these variations were stronger for invasive lobular than for invasive ductal carcinoma. Similarly, invasive lobular carcinoma is more strongly associated with early menarche, late menopause and late age at first birth. As for genetic risk factors, four high-penetrance genes are tested in clinical practice when genetic susceptibility to breast cancer is suspected, BRCA1, BRCA2, TP53 and CDH1. Germline mutations in BRCA1 and TP53 are predominantly associated with invasive ductal carcinoma, while BRCA2 mutations are associated with both ductal and lobular cancers. CDH1, the gene coding for the E-cadherin adhesion protein, is of special interest as mutations are associated with invasive lobular carcinoma, but never with ductal carcinoma. It was initially known as the main susceptibility gene for gastric cancer of the diffuse type, but the excess of breast cancers of the lobular type in CDH1 families led researchers to identify it also as a susceptibility gene for invasive lobular carcinoma. The risk of invasive lobular carcinoma is high in female mutation carriers, as about 50% are expected to develop the disease. Carriers must therefore undergo intensive breast cancer screening, with, for example, yearly magnetic resonance imaging and mammogram starting at age 30 years.

Invasive lobular breast cancer: the prognostic impact of histopathological grade, E-cadherin and molecular subtypes

Aims

The aim of this study was to compare breast cancer specific survival (BCSS) for invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC) and, further, to evaluate critically the prognostic value of histopathological grading of ILC and examine E-cadherin as a prognostic marker in ILC.

Methods and results

The study comprised 116 lobular and 611 ductal breast carcinomas occurring between 1961 and 2008. All cases had been classified previously according to histopathological type and grade, stained for oestrogen receptor (ER), progesterone receptor (PR), antigen Ki67 (Ki67), epithelial growth factor receptor (EGFR), cytokeratin 5 (CK5) and human epidermal growth factor receptor 2 (HER2) and classified into molecular subtypes. For the present study, immunohistochemical staining for E-cadherin was performed. The Kaplan–Meier method and Cox proportional hazards models were used in the analyses. Grade 2 tumours comprised 85.3% of the lobular tumours and 51.9% of the ductal tumours. BCSS in ILC grade 2 was comparable to that of IDC grade 3. E-cadherin-negative ILC had a poorer prognosis compared to E-cadherin positive ILC and to IDC regardless of E-cadherin status.

Conclusions

The implication of histopathological grading may differ in ILC compared to IDC. E-cadherin may be useful in prognostication in ILC and thereby influence the determination of treatment strategies for this group of women.