Characterisation of male breast cancer: a descriptive biomarker study from a large patient series

Male breast cancer: a multicenter study to provide a guide for proper management

INTRODUCTION

To offer an extensive retrospective experience on the management of male breast cancer.

METHODS

A multicenter retrospective observational cohort study was conducted, including male patients diagnosed with breast cancer (invasive or in situ) in 12 Italian breast units from January 1975 to December 2019. Patients aged 18 years or older were assessed for eligibility. Exclusion criteria were metastatic cancer at diagnosis, previous cancer(s), received neoadjuvant treatment, incomplete data on (neo) adjuvant treatment(s), and/or follow-up data. Data on radiological examinations, demographic characteristics, risk factors, histological features, receptor status, treatments, and follow-up were collected.

RESULTS

In a series of 671 male patients with breast cancer assessed for eligibility, 403 (28 in situ and 375 invasive neoplasms) were included in the study. All included patients underwent surgery. The median age at surgery was 63.8 years (IQR 56.1-72.1). In 68% of cases, patients underwent echography, and in 55.1%, a mammography. Most patients were ER and PR positive (63.8%), HER2 negative (80.4%), with high (≥ 20%) Ki67 values (61.3%), and luminal B subtype (51.1%). The 10-year overall survival was 73.6% (95% CI 67.0-79.1) for invasive breast cancer and 90% (95% CI 65.6-97.4) for in situ breast cancer. In patients with invasive breast cancer, at univariable analysis, having a G3 tumor (vs. G1), pT2/3/4 (vs. pT1), pN2/3 (vs. pN0), luminal B subtype with Ki67 ≥ 20% (vs. Luminal A), were significantly associated with a higher risk of death. In multivariable analyses, pT2/3/4 (vs. pT1) remained significantly associated with a higher risk of death (HR 3.14, 95% CI 1.83-5.39), and having a HER2 positive or a triple-negative subtype (vs. Luminal A) was also significantly associated with a higher risk of mortality (HR 4.76, 95% CI 1.26-18.1).

CONCLUSION

Male breast cancer is a rare disease, the better understanding of which is necessary for a more effective diagnostic and therapeutic approach.

Biological Basis of Breast Cancer-Related Disparities in Precision Oncology Era

Precision oncology is based on deep knowledge of the molecular profile of tumors, allowing for more accurate and personalized therapy for specific groups of patients who are different in disease susceptibility as well as treatment response. Thus, onco-breastomics is able to discover novel biomarkers that have been found to have racial and ethnic differences, among other types of disparities such as chronological or biological age-, sex/gender- or environmental-related ones. Usually, evidence suggests that breast cancer (BC) disparities are due to ethnicity, aging rate, socioeconomic position, environmental or chemical exposures, psycho-social stressors, comorbidities, Western lifestyle, poverty and rurality, or organizational and health care system factors or access. The aim of this review was to deepen the understanding of BC-related disparities, mainly from a biomedical perspective, which includes genomic-based differences, disparities in breast tumor biology and developmental biology, differences in breast tumors' immune and metabolic landscapes, ecological factors involved in these disparities as well as microbiomics- and metagenomics-based disparities in BC. We can conclude that onco-breastomics, in principle, based on genomics, proteomics, epigenomics, hormonomics, metabolomics and exposomics data, is able to characterize the multiple biological processes and molecular pathways involved in BC disparities, clarifying the differences in incidence, mortality and treatment response for different groups of BC patients.

Exploring the One Health Paradigm in Male Breast Cancer

How cancer patterns in humans compare to those of other species remains largely unknown and there is an even bigger knowledge gap for rare cancers like male breast cancer. One Health is a convergence of human and animal healthcare that encourages cross-pollination of medical research uniting human and veterinary medicine. Recognising that breast cancer occurs spontaneously in other male species (e.g. primates, canines, felines), and knowing that no laboratory models exist for male breast cancer, which limits our ability to perform functional studies, we explored the feasibility of applying One Health to breast cancer in men by conducting a narrative review of the topic. Spontaneous development of breast cancer was reported in captive male primates and in companion canines and felines. Some parallels in tumour biology of human male breast cancer with canines and primates were found. The age distribution, pattern of biomarker expression and metastasis were similar, with mammary tumours typically detected after two-thirds of average lifespan. However, instances of triple negative and inflammatory breast cancer, which are rarely observed in human male breast cancer, were found in canines and histological classification was inconsistent between species. These disparities need redressing to enable full exploration of the One Health paradigm in rare cancers.

Adjuvant chemotherapy and survival in males aged 70 years or older with breast cancer: a population-based retrospective study

BACKGROUND

Male breast cancer constitutes a minority of breast cancer diagnoses, yet its incidence has been on the rise in recent decades. However, elderly male breast cancer patients have been inadequately represented in clinical trials, posing challenges in treatment decisions. This study seeks to clarify the efficacy of chemotherapy in this demographic and identify the population most likely to benefit from such intervention.

METHODS

We conducted a retrospective analysis using the Surveillance, Epidemiology, and End Results (SEER) database, encompassing a total of 1900 male breast cancer patients aged 70 years or older. Among them, 1652 were categorized in the no-chemotherapy group, while 248 were in the chemotherapy group. A multifactorial logistic regression model was employed to investigate the determinants influencing the administration of chemotherapy in elderly male breast cancer patients. Additionally, the multivariate Cox proportional hazards regression model was applied to identify factors associated with outcomes, with overall survival (OS) as the primary endpoint.

RESULTS

Multivariate logistic regression analysis revealed that grade, tumor size, and nodal status were robust predictors for elderly male breast cancer patients receiving chemotherapy. Furthermore, the multivariate analysis demonstrated that chemotherapy conferred benefits compared to the no-chemotherapy group (HR = 0.822, 95% CI: 0.682-0.991, p = 0.040). Stratified analyses indicated that individuals with N+, poorly/undifferentiated grade, and stage II/III disease could derive benefits from chemotherapy. Upon further investigation of progesterone receptor (PR) positive patients, it was found that only stage III patients experienced significant benefits from chemotherapy (HR = 0.571, 95% CI: 0.372-0.875, p = 0.010). Conversely, in PR negative patients, both stage II (HR = 0.201, 95% CI: 0.051-0.792, p = 0.022) and stage III patients (HR = 0.242, 95% CI: 0.060-0.972, p = 0.046) derived benefits from chemotherapy.

CONCLUSION

Adjuvant chemotherapy may benefit certain elderly male breast cancer patients, specifically those with positive lymph node status, poorly/undifferentiated grade, and PR-positive in stage III, as well as PR-negative expression in stage II/III. Given favorable physical tolerance, it is advisable not to hastily dismiss chemotherapy for these elderly male breast cancer patients.

Clinical characteristics and prognostic factors of male breast cancer in China

Purpose

This study aimed to explore the clinical characteristics of male breast cancer (MBC) patients and the factors influencing their prognosis.

Methods

We conducted a retrospective case series analysis of 117 MBC cases who were treated at Zhejiang Cancer Hospital from 2009 to 2022. Cox proportional hazard model was used to identify prognostic factors of MBC. Nomogram was constructed based on these factors, which was further evaluated by C-index and calibration curves.

Results

A total of 115 MBC cases were finally included in our analyses, with median diagnosis age of 59 years. Of these cases, 80.0% were estrogen receptor (ER) positive, 79.2% were progesterone receptor (PR) positive, 48.7% were human epidermal growth factor receptor 2 (HER2) negative, and 42.6% had Ki67 levels higher than 15%. 108 (93.9%) cases underwent radical mastectomy, while only 3 (2.6%) received breast-conserving surgery. The Logrank test suggested that lymphocyte-to-monocyte ratio (LMR) was negatively associated with both overall survival (OS) and disease-free survival (DFS) of MBC, while platelet-to-lymphocyte ratio (PLR) and neutrophil-to-lymphocyte ratio (NLR) were only positively associated with OS (all P-values < 0.05). Multivariate regression analysis showed that age (HR 1.08, 95% CI 1.03-1.13) was significant prognostic factors for OS. Meanwhile, age (HR 1.06, 95% CI 1.02-1.10), histological differentiation grade (poorly differentiated/undifferentiated vs. well-differentiated: HR 2.55, 95% CI 1.05-6.17), and TNM stage (IV vs. I: HR 31.59, 95% CI 6.01-165.93) were also significant prognostic factors for DFS. Nomograms were developed for DFS, with C-indexes of 0.782, indicating good predictive performance.

Conclusion

Increased age, bigger tumor size, higher TNM stage, and lower histological differentiation grade were associated with poor MBC prognosis, and LMR, PLR, and NLR might be potential predictors for MBC prognosis.

Time Trends in Male Breast Cancer Incidence, Mortality, and Survival in Austria (1983-2017)

Background

Male breast cancer (MBC) comprises less than 1% of all breast cancer cases globally and remains understudied with persisting sex-specific survival disadvantages. We aim to contribute to better understanding of MBC with a comprehensive analysis of time-trends over several decades in Austria.

Methods

We used Austrian National Cancer Registry data on 1648 cases of MBC cases diagnosed between 1983 and 2017 in Austria. Overall incidence, mortality, and survival rates, as well as age-, stage-, and period-specific incidence and survival rates were calculated. Joinpoint regression was performed to assess trends.

Results

MBC incidence rates increased throughout the whole observation period (1983-2017) with an annual percent change (APC) of 1.44% (95% confidence interval, CI: 0.77 to 2.11). During the same period, morality rates were stable (APC: -0.25, 95% CI: -0.53 to 0.60). Ten-year survival rates showed three phases of decreasing increases with an average APC of 2.45%, 1983-2009 (95% CI: 2.1 to 2.74). Five-year survival rates improved until 2000 (APC: 2.31, 95% CI: 1.34 to 3.30) and remained stable thereafter (APC: 0.10, 95% CI: -0.61 to 0.80). Stage-specific analyses showed a single trend of stable incidence rates of distant disease MBC (APC: -0.03, 95% CI: -1.67 to 1.65). Further, we observed increases in localised, regional, and unknown stage cancer incidence and increases in incidence rates across all age groups over the whole observation period. However, the estimates on these subgroup-specific trends (according to age- and stage) show wider 95% CIs and lower bounds closer to zero or negative in comparison to our findings on overall incidence, mortality, and survival.

Conclusion

Despite improvements in survival rates, MBC mortality rates remained largely stable between 1983 and 2017 in Austria, possibly resulting from a balance between increasing overall incidence and stable incidence rates of distant disease MBC.

Treatments Targeting the Androgen Receptor and Its Splice Variants in Breast Cancer

Breast cancer is a major cause of death worldwide. The complexity of endocrine regulation in breast cancer may allow the cancer cells to escape from a particular treatment and result in resistant and aggressive disease. These breast cancers usually have fewer treatment options. Targeted therapies for cancer patients may offer fewer adverse side effects because of specificity compared to conventional chemotherapy. Signaling pathways of nuclear receptors, such as the estrogen receptor (ER), have been intensively studied and used as therapeutic targets. Recently, the role of the androgen receptor (AR) in breast cancer is gaining greater attention as a therapeutic target and as a prognostic biomarker. The expression of constitutively active truncated AR splice variants in breast cancer is a possible mechanism contributing to treatment resistance. Therefore, targeting both the full-length AR and AR variants, either through the activation or suppression of AR function, depending on the status of the ER, progesterone receptor, or human epidermal growth factor receptor 2, may provide additional treatment options. Studies targeting AR in combination with other treatment strategies are ongoing in clinical trials. The determination of the status of nuclear receptors to classify and identify patient subgroups will facilitate optimized and targeted combination therapies.

HER2-Low Expression in Male Breast Cancer: Results from a Multicenter Series in Italy

In the field of breast cancer care, a significant breakthrough has occurred with the recognition of HER2-low expression as a target for novel anti-HER2 antibody-drug conjugates (ADC). This discovery is reshaping the treatment landscape, challenging previous perceptions that considered HER2-low as clinically insignificant. The ability to target HER2-low expression is expected to have substantial clinical implications, irrespective of gender, including in cases of male breast cancer (MBC). However, an estimate of the prevalence of the HER2-low subtype in MBC is missing. This retrospective, observational, multicenter study was aimed at characterizing the HER2-low subtype in MBC. For the purpose of this study, the three-tiered categorization of HER2 (HER2-0, HER2-low, and HER2-positive) was used to reclassify the HER2-negative group into HER-0 or HER2-low subtypes. In the whole series of 144 invasive MBCs, 79 (54.9%) were HER2-0 (IHC scores of 0), 39 (27.1%) HER2-low (IHC scores of 1+/2+ with negative ISH), and 26 (18.0%) HER2-positive (IHC scores of 3+/2+ with positive ISH). Specifically, among hormone receptor-positive (HR+) HER2-negative invasive MBCs, 34.8% were HER2-low and 65.2% HER2-0. Compared with HER2-0, HER2-low subtype was associated with a positive lymph node involvement (p = 0.01). Other pathologic characteristics including histology, staging, and grading did not show notable variations between the two subtypes. The presence of germline BRCA1/2 pathogenic variants (PVs) did not significantly differ between HER2-0 and HER2-low MBCs. However, about 13% of HER2-low MBCs had germline PVs in BRCA1/2 genes, mainly BRCA2, a clinically relevant observation in the context of combined target therapy. Overall, our data, which focused on the largest gender-specific breast cancer series, to our knowledge, confirm that the emerging three-tiered categorization of HER2 (HER2-0, HER2-low, and HER2-positive) can also be considered in MBC, to mitigate both the gender gap and the underrepresentation of males in clinical trials.

Clinicopathological analysis of 38 male patients diagnosed with breast cancer

BACKGROUND

Male breast cancer (MBC) accounts for one percent of all breast cancers. Due to the lack of awareness and routine screening programs, most patients present with systemic disease at the time of diagnosis with low overall survival.

OBJECTIVES

This study aims to investigate the prognostic factors of male breast cancer and its correlation with established prognostic parameters and patient outcomes.

METHODS

Thirty-eight male breast cancer patients are identified from the MKA Breast Cancer Clinic database, and their corresponding clinical and pathological characteristics are obtained. Cut-off values of 1% and 10% are applied to further classify ER and PR results.

RESULTS

Older men are more likely to develop MBC than younger men and are more likely to have spread to axillary lymph nodes. Invasive ductal carcinoma is a more common histologic type in MBC. All the tested patients have ER and PR positivity. Distant metastasis developed in 17/38 (44.7%) patients. Bone metastasis is seen commonly in metastatic MBC.

CONCLUSIONS

According to our cohort, MBC is seen in older males, presents in later stages, and shows hormone receptor positivity and a tendency to bone involvement. MBC is a heterogenous but distinct biological entity requiring a specific clinical and pathological approach.

Risk factors for male breast cancer

Male breast cancer (MBC) presents problems with identification of high-risk groups. Risk factors include hepatic dysfunction, high ambient working temperature, exposure to exhaust fumes and obesity, but none identify a group with a high absolute number of MBC cases. The two significant cohorts are BRCA2 mutation carriers and individuals with Klinefelter's syndrome (KS), responsible for up to 15% of cases. Since >90% of male tumours are ER+ve, endocrine intervention is logical with the likely agent being tamoxifen. In terms of an acceptable endocrine agent, compliance studies. Compliance studies indicate that men do not tolerate tamoxifen well because of side-effects. Although certain groups with an increased risk of MBC can be identified, the absolute number of cases is small so, at present, a meaningful prevention study is not an option.

Clinical, Pathological, and Prognostic Features of Male Breast Cancer: A Multicenter Study

Male breast cancer (BC) represents less than 1% of male tumors. Little is known about male BC characteristics, management, and survival, with many studies based on a small number of cases. Consequently, the treatment of male BC lacks specific guidelines. The aims of the study are to compare male and female breast cancer (FBC) in terms of cancer clinical and anatomopathological features and treatment approach, and to identify differences between male BC and FBC in terms of survival. Patients and methods: Data from 2006 to 2018 were retrospectively acquired. Amounts of 49 males and 680 postmenopausal females with primary non-metastatic BC who underwent breast surgery at Mauriziano Hospital or IRCCS Candiolo (TO-Italy) were included. The mean age at diagnosis for male BC was 68.6 years, and males presented a smaller tumor size than women (p < 0.05) at diagnosis. Most male BC patients received adjuvant endocrine therapy (AET) with tamoxifen (73.5%). AET drop-out rate due to side effects was 16.3% for males compared to 7.6% for women (p = 0.04). Comparing FBC and male BC, no differences have been identified in terms of DFS and OS, with a similar 10-year-relapse rate (12% male BC vs. 12.4% FBC). Propensity Score Matching by age, nodal status, pT, and molecular subtype had been performed and no differences in OS and DFS were seen between male BC and FBC. In conclusion, male BC and FBC have similar prognostic factors and survival outcomes. The drop-out rate of AET was higher in males, and side effects were the main reason for drug discontinuation.

Prediction models for hormone receptor status in female breast cancer do not extend to males: further evidence of sex-based disparity in breast cancer

Breast cancer prognosis and management for both men and women are reliant upon estrogen receptor alpha (ERα) and progesterone receptor (PR) expression to inform therapy. Previous studies have shown that there are sex-specific binding characteristics of ERα and PR in breast cancer and, counterintuitively, ERα expression is more common in male than female breast cancer. We hypothesized that these differences could have morphological manifestations that are undetectable to human observers but could be elucidated computationally. To investigate this, we trained attention-based multiple instance learning prediction models for ERα and PR using H&E-stained images of female breast cancer from the Cancer Genome Atlas (TCGA) (n = 1085) and deployed them on external female (n = 192) and male breast cancer images (n = 245). Both targets were predicted in the internal (AUROC for ERα prediction: 0.86 ± 0.02, p < 0.001; AUROC for PR prediction = 0.76 ± 0.03, p < 0.001) and external female cohorts (AUROC for ERα prediction: 0.78 ± 0.03, p < 0.001; AUROC for PR prediction = 0.80 ± 0.04, p < 0.001) but not the male cohort (AUROC for ERα prediction: 0.66 ± 0.14, p = 0.43; AUROC for PR prediction = 0.63 ± 0.04, p = 0.05). This suggests that subtle morphological differences invisible upon visual inspection may exist between the sexes, supporting previous immunohistochemical, genomic, and transcriptomic analyses.

Trichorhinophalangeal syndrome type 1 (TRPS1) expression in male breast carcinoma

Currently, there is a paucity of highly specific and sensitive markers to identify breast carcinoma in male patients. Immunohistochemical stains commonly used for unmasking primary breast carcinomas include estrogen receptor (ER) and GATA3. However, these markers are commonly expressed in carcinomas originating from other organ systems and can be reduced in breast carcinomas with higher histologic grades. Androgen receptor (AR) may be used to highlight primary male breast cancer, but this marker can also be expressed in other carcinomas. We evaluated TRPS1, a highly sensitive and specific marker for female breast carcinoma, in cases of male breast carcinoma. Through an institutional database search, we identified 72 cases of primary invasive breast carcinoma in male patients. Among ER/progesterone receptor (PR)-positive cancers, 97% showed intermediate or high positivity for both TRPS1 and GATA3. Among HER2-positive cancers, 100% showed intermediate or high positivity for TRPS1 and GATA3. One case of triple-negative breast cancer was collected, showing high positivity for TRPS1 and negativity for GATA3. AR staining was non-specific and heterogeneous: 76% showed high positivity, but the remaining 24% showed low or intermediate positivity. Additionally, among 29 cases of metastatic carcinoma to male breast tissue, 93% were negative for TRPS1, and the remaining 2 cases (7%), which were carcinomas from salivary gland primary tumors, were intermediate positive. TRPS1 is a sensitive and specific marker in the unmasking of male primary invasive breast carcinoma across different subtypes. Additionally, TRPS1 is not expressed in metastatic carcinomas of multiple primaries, with the exception of salivary gland primaries.

The prediction of distant metastasis risk for male breast cancer patients based on an interpretable machine learning model

OBJECTIVES

This research was designed to compare the ability of different machine learning (ML) models and nomogram to predict distant metastasis in male breast cancer (MBC) patients and to interpret the optimal ML model by SHapley Additive exPlanations (SHAP) framework.

METHODS

Four powerful ML models were developed using data from male breast cancer (MBC) patients in the SEER database between 2010 and 2015 and MBC patients from our hospital between 2010 and 2020. The area under curve (AUC) and Brier score were used to assess the capacity of different models. The Delong test was applied to compare the performance of the models. Univariable and multivariable analysis were conducted using logistic regression.

RESULTS

Of 2351 patients were analyzed; 168 (7.1%) had distant metastasis (M1); 117 (5.0%) had bone metastasis, and 71 (3.0%) had lung metastasis. The median age at diagnosis is 68.0 years old. Most patients did not receive radiotherapy (1723, 73.3%) or chemotherapy (1447, 61.5%). The XGB model was the best ML model for predicting M1 in MBC patients. It showed the largest AUC value in the tenfold cross validation (AUC:0.884; SD:0.02), training (AUC:0.907; 95% CI: 0.899-0.917), testing (AUC:0.827; 95% CI: 0.802-0.857) and external validation (AUC:0.754; 95% CI: 0.739-0.771) sets. It also showed powerful ability in the prediction of bone metastasis (AUC: 0.880, 95% CI: 0.856-0.903 in the training set; AUC: 0.823, 95% CI:0.790-0.848 in the test set; AUC: 0.747, 95% CI: 0.727-0.764 in the external validation set) and lung metastasis (AUC: 0.906, 95% CI: 0.877-0.928 in training set; AUC: 0.859, 95% CI: 0.816-0.891 in the test set; AUC: 0.756, 95% CI: 0.732-0.777 in the external validation set). The AUC value of the XGB model was larger than that of nomogram in the training (0.907 vs 0.802) and external validation (0.754 vs 0.706) sets.

CONCLUSIONS

The XGB model is a better predictor of distant metastasis among MBC patients than other ML models and nomogram; furthermore, the XGB model is a powerful model for predicting bone and lung metastasis. Combining with SHAP values, it could help doctors intuitively understand the impact of each variable on outcome.

Defining genomic, transcriptomic, proteomic, epigenetic, and phenotypic biomarkers with prognostic capability in male breast cancer: a systematic review

Although similar phenotypically, there is evidence that male and female breast cancer differ in their molecular landscapes. In this systematic review, we consolidated all existing prognostic biomarker data in male breast cancer spanning genetics, transcriptomics, proteomics, and epigenetics, and phenotypic features of prognostic value from articles published over a 29-year period (March 16, 1992, to May 1, 2021). We identified knowledge gaps in the existing literature, discussed limitations of the included studies, and outlined potential approaches for translational biomarker discovery and validation in male breast cancer. We also recognised STC2, DDX3, and DACH1 as underexploited markers of male-specific prognostic value in breast cancer. Finally, beyond describing the cumulative knowledge on the extensively researched markers oestrogen receptor-α, progesterone receptor, HER2, androgen receptor, and BRCA2, we highlighted ATM, CCND1, FGFR2, GATA3, HIF1-α, MDM2, TP53, and c-Myc as well studied predictors of poor survival that also aligned with several hallmarks of cancer.

Tumor Microenvironment in Male Breast Carcinoma with Emphasis on Tumor Infiltrating Lymphocytes and PD-L1 Expression

Male breast cancer (MBC) is rare and usually presents as a locally advanced disease. Stromal tumor-infiltrating lymphocytes (sTILs) are associated with a better response to neoadjuvant chemotherapy and improved prognosis in all molecular subtypes of female breast cancer, but their role in MBC is less clear. We studied sTILs and the expression of programmed cell death ligand 1 (PD-L1) and pan-TRK in MBC. We retrospectively studied 113 cases of MBC surgically treated between 1988 and 2015. The tumors were evaluated for histological type and grade, stage, intrinsic subtype and sTILs. We performed immunohistochemistry for PD-L1 (clone SP142) and pan-TRK (clone EPR17341) on tissue microarrays. Pan-TRK positive cases were further analyzed by next-generation sequencing. The median age was 69 years (range 60−77). Invasive carcinoma of no special type was found in 94.7% of cases, of which 53.1% were grade 2. Estrogen receptor was positive in 92% of the tumors, progesterone receptor in 85.8%, androgen receptor in 70.8%; 4.4% were human epidermal growth factor receptor 2 (HER2)-positive, and 55.8% HER2-low. 40.7% of tumors were luminal A and 51.3% luminal B, 4.4% HER2-enriched and 3.5% triple negative carcinoma. sTILs density was <50% in 96.4% of the tumors, >50% in 3.6% of the tumors. PD-L1 immune cell score >1% was found in 7.1% of the tumors (all of luminal subtype). A weak focal cytoplasmic pan-TRK staining was present in 8.8% but without NTRK fusion. Neither sTILs nor PD-L1 had statistically significant outcomes. Our findings suggest that a subset of MBC patients harbors an immunological environment characterized by increased sTILs with PD-L1 expression. These patients may potentially benefit from immune checkpoint inhibitor therapy. Frequent HER2-low may offer novel anti-HER2 treatment options.

The role of postoperative radiation therapy in stage I–III male breast cancer: A population-based study from the surveillance, epidemiology, and End Results database

Background

This study aimed to investigate the role of postoperative radiation therapy in a large population-based cohort of patients with stage I–III male breast cancer (MaBC).

Methods

Patients with stage I–III breast cancer treated with surgery were selected from the Surveillance, Epidemiology, and End Results cancer database from 2010 to 2015. Multivariate logistic regression identified the predictors of radiation therapy administration. Multivariate Cox regression model was used to evaluate the predictors of survival.

Results

We identified 1321 patients. Age, stage, positive regional nodes, surgical procedure, and HER2 status were strong predictors of radiation therapy administration. There was no difference between patients who received radiation therapy and those who did not (P = 0.46); however, after propensity score matching, it was associated with improved OS (P = 0.04). In the multivariate analysis of the unmatched cohort, the factors associated with better OS were administration of radiation therapy and chemotherapy. In the subset analysis of the unmatched cohort, postoperative radiation therapy was associated with improved OS in men undergoing breast-conserving surgery (BCS), with four or more node-positive or larger primary tumours (T3/T4). Furthermore, we found no benefit of radiation therapy, regardless of the type of axillary surgery in mastectomy (MS). In older MaBC patients with T1-2N1 who underwent MS, radiation therapy showed no significant effects, regardless of chemotherapy.

Conclusion

Postoperative radiation therapy could improve the survival of MaBC patients undergoing BCS, with four or more node-positive or larger primary tumours. Moreover, it should be carefully considered in patients undergoing MS and older T1-2N1 patients.

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Postoperative radiation therapy may improve survival of some male breast cancer patients.

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Patients undergoing breast-conserving surgery or with large tumours may benefit.

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Radiation therapy had no benefits in mastectomy regardless of axillary surgery type.

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Radiation therapy was not effective in older T1-2N1 patients with receiving mastectomy.

FOXA1 in Breast Cancer: A Luminal Marker with Promising Prognostic and Predictive Impact

The present review focuses on the function of the forkhead protein FOXA1 in breast cancer (BC) in relation to steroid hormone receptors. We explored the currently available analytic approaches for FOXA1 assessment both at gene and protein levels, comparing the differences between the available techniques used for its diagnostic assessment. In addition, we elaborated on data regarding the prognostic and predictive role of this marker in BC based on several studies that evaluated its expression in relation to the outcome and/or response to therapy. FOXA1, similar to the androgen receptor (AR), may have a dual role in BC according to hormonal status. In luminal cancers, its expression contributes to a better prognosis, while in triple-negative breast cancers (TNBC), it implies an adverse outcome. Consequently, we observed that FOXA1-positive expression in a neoadjuvant setting may predict a lack of response in luminal BC as opposed to TNBC, in which FOXA1 allegedly increases its chemosensitivity. In conclusion, considering its accessible and convenient identification by immunohistochemistry, its important impact on prognosis, and its suitability to identify patients with different responses to chemotherapy, we propose that FOXA1 could be tested in routine diagnostics as an additional prognostic and predictive marker in BC.

Analysis of the Clinical Advancements for BRCA-Related Malignancies Highlights the Lack of Treatment Evidence for BRCA-Positive Male Breast Cancer

Male breast cancer (MBC) is a rare disease that accounts for less than 1% of all breast cancers and male malignancies. Despite recognised clinico-pathological and molecular differences to female breast cancer (FBC), the clinical management of MBC follows established FBC treatment strategies. Loss of function mutations in the DNA damage response genes BRCA1 and BRCA2, have been strongly implicated in the pathogenesis of MBC. While there have been extensive clinical advancements in other BRCA-related malignancies, including FBC, improvements in MBC remain stagnant. Here we present a review that highlights the lack of treatment evidence for BRCA-related MBC and the required national and global collaborative effort to address this unmet need. In doing so, we summarise the transformative clinical advancements with poly(ADP-ribose) polymerase (PARP) inhibitors in other BRCA-related cancers namely, FBC and prostate cancer.

Morphological Features and Immunohistochemical Profiling of Male Breast Gynaecomastia; A Large Tissue Microarray Study

Introduction

Gynaecomastia is the commonest male breast condition accounting for approximately 85% of male breast lesions. There is minimal information on the immunohistochemical profile of gynaecomastia. We aimed to comprehensively profile a large series of gynaecomastia samples for putative mammary diagnostic, predictive and prognostic markers.

Methods

A total of 156 samples, were histologically reviewed, assembled onto tissue microarrays, and stained for oestrogen receptors (ERα, ERβ1, ERß2), progesterone receptors (total PR, PRα), androgen receptor (AR), basal & luminal cytokeratins (CK5/6, CK14, CK8/18) and the proliferation marker Ki67. Relevant cut offs for marker positivity were defined based on existing literature: AR (10%), ERα and PR (Allred score >3/8), ERß (10% and 20%), cytokeratins (10%) and Ki67 (10% and 20%).

Results

108 samples from 86 patients aged 13-75 years were available for immunohistochemical assessment. 73.1% of the lesions were AR positive, compared to 99% for ERα and 100% for both ERß1 and ERß2. 98% of samples were positive for total PR and 97.1% for PRα. 69.8% expressed CK5/6 whilst 57% were CK14 positive. A tri-layered pattern of cytokeratin expression was also observed. Ki67 positivity was low with 17.1% and 6.7% classified as Ki67 positive using 10% and 20% cut off values respectively. A significant negative correlation was found between ERα expression and patient age (rs = -0.221, p=0.023). Bivariate correlations were produced, and comparisons made with previously published data regarding the immunohistochemical status in normal female breast tissue, proliferative and neoplastic breast diseases of the female and male breast.

Conclusions

Hormone receptors, including oestrogen receptor α and ß isoforms as well as androgen receptors were abundantly expressed within the intraductal luminal hyperplastic epithelium in gynaecomastia supporting the hormonal role in the pathogenesis and treatment. ERα, ERβ1 and ERβ2 were expressed in a higher proportion of cells compared with their expression in the female breast benign lesions which further characterises gynaecomastia biology. The identification of a low Ki67 proliferative index and the mixed cytokeratin profile in gynaecomastia differentiates this benign condition from male breast cancer. Therefore, Ki67 and cytokeratins can help in the differential diagnosis from histological mimics in the routine diagnostic work up.

Male Breast Cancer: From Molecular Genetics to Clinical Management

MBC is a rare disease accounting for almost 1% of all cancers in men and less than 1% of breast cancer. Emerging data on the genetic drivers of predisposition for MBC are available and different risk factors have been associated with its pathogenesis. Genetic alterations, such as pathogenetic variants in BRCA1/2 and other moderate-/low-penetrance genes, along with non-genetic risk factors, have been recognized as pathogenic factors for MBC. Preventive and therapeutic implications could be related to the detection of alterations in predisposing genes, especially BRCA1/2, and to the identification of oncogenic drivers different from FBC. However, approved treatments for MBC remain the same as FBC. Cancer genetic counseling has to be considered in the diagnostic work-up of MBC with or without positive oncological family history. Here, we review the literature, reporting recent data about this malignancy with a specific focus on epidemiology, and genetic and non-genetic risk factors. We introduce the perspective of cancer genetic counseling for MBC patients and their healthy at-risk family members, with a focus on different hereditary cancer syndromes.

Management of Male Breast Cancer: The Journey so Far and Future Directions

Male breast cancer is now shown to be a unique entity and should be considered as a distinct disease. Given the relatively smaller number of cases, randomized controlled trials for treatment are extremely limited and majority of practices are derived from female breast cancer studies. This paper reviews available literature on surgical, radiation, and systemic therapies for male breast cancer, and discusses current practice recommendations.

Is it time to consider the Androgen receptor as a therapeutic target in breast cancer?

Breast cancer (BC) is a heterogeneous disease and the most prevalent malignant tumor in women worldwide. The majority of BC cases are positive for estrogen receptor (ER) and progesterone receptor (PgR), both known to be involved in cancer pathogenesis, progression, and invasion. In line with this, hormonal deprivation therapy appears to be a useful tool and an effective treatment for these BC subtypes. Unfortunately, prognosis among patients with hormone-negative tumors or therapy-refractory and metastatic patients remains poor. Novel biomarkers are urgently needed in order to predict the course of the disease, make better therapy decisions and improve the overall survival of patients. In this respect, the androgen receptor (AR), a member of the hormonal nuclear receptor superfamily and ER and PgR, emerges as an interesting feature widely expressed in human BCs. Despite the advances, the precise tumorigenic mechanism of AR and the role of its endogenous ligands are yet not well-understood. In this review, we aim to elaborate on the prognostic impact of AR expression and current AR-targeting approaches based on previous studies investigating AR's role in different BC subtypes.

A biomarker study in Peruvian males with breast cancer

BACKGROUND

Breast cancer (BC) frequency in males is extremely low and tumor features vary from its female counterpart. Breast cancer clinical and pathological features differ by race in women. Tumor infiltrating lymphocyte (TIL) levels, mismatch repair (MMR) protein loss, androgen receptor (AR) expression, and PIK3CA gene mutations are predictive biomarkers of response to biological therapy in female BC. There is limited information about clinical and pathological features as well as predictive biomarkers in males of non-Caucasian races with BC.

AIM

To investigate clinicopathological features and biomarkers of BC tumors in males and their prognostic value in Peruvian population.

METHODS

This study looked at a single-institution series of 54 Peruvian males with invasive BC who were diagnosed from Jan 2004 to June 2018. Standard pathological features, TIL levels, MMR proteins, AR immunohistochemistry staining, and PIK3CA gene mutations were prospectively evaluated in cases with available paraffin material. Percentage of AR and estrogen receptor (ER) positive cells was additionally calculated by software after slide scanning. Statistical analyses included association tests, intraclass correlation test and Kaplan Meier overall survival curves.

RESULTS

The median age was 63 years and most cases were ER-positive (85.7%), HER2 negative (87.2%), Luminal-A phenotype (60%) and clinical stage II (41.5%) among our male breast tumors. Median TIL was 10% and higher levels tended to be associated with Luminal-B phenotype and higher grade. AR-positive was found in 85.3% and was correlated with ER (intraclass index of 0.835, P < 0.001). Loss of MMR proteins was found in 15.4% and PIK3CA mutation (H1047R) in 14.3% (belonged to the Luminal-A phenotype). Loss of MMR proteins was associated with AR-negative (P = 0.018) but not with ER (P = 0.43) or TIL (P = 0.84). Early stages (P < 0.001) and lower grade (P = 0.006) were associated with longer overall survival. ER status, phenotype, AR status, TIL level, MMR protein loss nor PIK3CA mutation was not associated with survival (P > 0.05).

CONCLUSION

Male BC is usually ER and AR positive, and Luminal-A. MMR loss and PIK3CA mutations are infrequent. Stage and grade predicted overall survival in our South American country population.

Proteomics and its applications in breast cancer

Breast cancer is an individually unique, multi-faceted and chameleonic disease, an eternal challenge for the new era of high-integrated precision diagnostic and personalized oncomedicine. Besides traditional single-omics fields (such as genomics, epigenomics, transcriptomics and metabolomics) and multi-omics contributions (proteogenomics, proteotranscriptomics or reproductomics), several new "-omics" approaches and exciting proteomics subfields are contributing to basic and advanced understanding of these "multiple diseases termed breast cancer": phenomics/cellomics, connectomics and interactomics, secretomics, matrisomics, exosomics, angiomics, chaperomics and epichaperomics, phosphoproteomics, ubiquitinomics, metalloproteomics, terminomics, degradomics and metadegradomics, adhesomics, stressomics, microbiomics, immunomics, salivaomics, materiomics and other biomics. Throughout the extremely complex neoplastic process, a Breast Cancer Cell Continuum Concept (BCCCC) has been modeled in this review as a spatio-temporal and holistic approach, as long as the breast cancer represents a complex cascade comprising successively integrated populations of heterogeneous tumor and cancer-associated cells, that reflect the carcinoma's progression from a "driving mutation" and formation of the breast primary tumor, toward the distant secondary tumors in different tissues and organs, via circulating tumor cell populations. This BCCCC is widely sustained by a Breast Cancer Proteomic Continuum Concept (BCPCC), where each phenotype of neoplastic and tumor-associated cells is characterized by a changing and adaptive proteomic profile detected in solid and liquid minimal invasive biopsies by complex proteomics approaches. Such a profile is created, beginning with the proteomic landscape of different neoplastic cell populations and cancer-associated cells, followed by subsequent analysis of protein biomarkers involved in epithelial-mesenchymal transition and intravasation, circulating tumor cell proteomics, and, finally, by protein biomarkers that highlight the extravasation and distant metastatic invasion. Proteomics technologies are producing important data in breast cancer diagnostic, prognostic, and predictive biomarkers discovery and validation, are detecting genetic aberrations at the proteome level, describing functional and regulatory pathways and emphasizing specific protein and peptide profiles in human tissues, biological fluids, cell lines and animal models. Also, proteomics can identify different breast cancer subtypes and specific protein and proteoform expression, can assess the efficacy of cancer therapies at cellular and tissular level and can even identify new therapeutic target proteins in clinical studies.

Male breast cancer: an update

Male breast cancer (MBC) is rare, accounting for less than 1% of all breast cancer but the incidence has increased worldwide. Risk factors include increased longevity, obesity, testicular diseases and tumours, and germline mutations of BRCA2. BRCA2 carriers have 80 times the risk of the general population. Men generally present with breast cancer at an older age compared with women. Histologically, MBC is often of grade 2, hormone receptor positive, HER2 negative, and no special type carcinoma although in situ and invasive papillary carcinomas are common. Reporting and staging are similar to female breast cancer. Metastatic lesions to the male breast do occur and should be differentiated from primary carcinomas. Until recently, MBC was thought to be similar to the usual ER positive post-menopausal female counterpart. However, advances in MBC research and trials have highlighted significant differences between the two. This review provides an up to date overview of the biology, genetics, and histology of MBC with comparison to female breast cancers and differential diagnosis from histological mimics.

Genetic Landscape of Male Breast Cancer

Male breast cancer (MBC) is now considered molecularly different from female breast cancer (FBC). Evidence from studies indicates that common genetic and epigenetic features of FBC are not shared with those diagnosed in men. Genetic predisposition is likely to play a significant role in the tumorigenesis of this rare disease. Inherited germline variants in BRCA1 and BRCA2 account for around 2% and 10% of MBC cases, respectively, and the lifetime risk of breast cancer for men harboring BRCA1 and BRCA2 mutations is 1.2% and 6.8%. As for FBC, pathogenic mutations in other breast cancer genes have also been recently associated with an increased risk of MBC, such as PALB2 and CHEK2 mutations. However, while multigene germline panels have been extensively performed for BC female patients, the rarity of MBC has resulted in limited data to allow the understanding of the magnitude of risk and the contribution of recently identified moderate penetrance genes of FBC for MBC predisposition. This review gathers available data about the germline genetic landscape of men affected by breast cancer, estimated risk associated with these genetic variants, and current guidelines for clinical management.

Comparison between male and female breast cancer survival using propensity score matching analysis

Male breast cancer (MBC) is a rare disease. The few studies on MBC reported conflicting data regarding survival outcomes compared to women. This study has two objectives: to describe the characteristics of a single-cohort of MBC and to compare overall survival (OS) and disease-free survival (DFS) between men and women using the propensity score matching (PSM) analysis. We considered MBC patients (n = 40) diagnosed between January 2004 and May 2019. Clinical, pathological, oncological and follow-up data were analyzed. Univariate analysis was performed to determine the prognostic factors on OS and DFS for MBC. We selected female patients with BC (n = 2678). To minimize the effect of the imbalance of the prognostic factors between the two cohorts, the PSM method (1:3 ratio) was applied and differences in survival between the two groups were assessed. The average age of MBC patients was 73 years. The 5-year OS and DFS rates were 76.7% and 72.2% respectively. The prognostic factors that significantly influenced OS and DFS were tumor size and lymph node status. After the PSM, 5 year-OS was similar between MBC and FBC (72.9% vs 72.3%, p = 0.70) while we found a worse DFS for MBC (72.2% vs 91.4%, p  = 0.03). Our data confirmed previous reported MBC characteristics: we found a higher risk of recurrence in MBC compared to FMC but similar OS. MBC and FMC are different entities and studies are needed to understand its epidemiology and guide its management.

Poor prognosis of male triple-positive breast Cancer patients: a propensity score matched SEER analysis and molecular portraits

Background

The purpose of this study was to explore clinicalpathology features, molecular features and outcome of male breast cancer patients who expressed ER, PR as well as HER-2, namely triple-positive male breast cancer (TP-MBC), and compared them with triple-positive female breast cancer patients (TP-FBC).

Methods

TP-MBC and TP-FBC from 2010 to 2017 were selected from the Surveillance, Epidemiology, and End Results database (SEER). Kaplan-Meier plotter and multivariable Cox regression model were applied to analyse the difference between TP-MBC and TP-FBC on cancer-specific survival (CSS) and overall survival (OS). Propensity score matched (PSM) analysis was used to ensure well-balanced characteristics. 7 cases TP-MBC and 174 cases TP-FBC patients with the genomic and clinical information were identified from the cohort of The Cancer Genome Atlas (TCGA) and the Memorial Sloan Kettering (MSK).

Result

336 TP-MBC and 33,339 TP-FBC patients were taken into the study. The percentages of TP-MBC in MBC patients were higher than the rates of TP-FBC in FBC patients from 2010 to 2017 except 2012. Compared with TP-FBC, more TP-MBC were staged III (17.9% vs. 13.5%) or stage IV (11.0% vs. 6.9%). TP-MBC were more frequently to be older than 65-years-old (47.0% vs. 29.3%), Balck (15.2% vs. 10.8%), ductal carcinoma (91.7% vs. 84.4%) and metastases to lung (4.5% vs. 2.1%) or bone (8.6% vs. 4.7%). TP-MBC had worse OS and CSS than TP-FBC in all stages (P < 0.001). In multivariable prediction model of TPBC, male patients had a higher risk than female. Lastly, the worse OS (P < 0.001) and CSS (P = 0.013) were seen in the 1:3 PSM analysis between TP-MBC and TP-FBC. Genomic analysis revealed that TP-MBCs have some notable rare mutations, like ERBB2, ERBB3, RB1, CDK12, FGFR2, IDH1, AGO2, GATA3, and some of them are not discovered in TP-FBC.

Conclusion

TP-MBC had a worse survival than TP-FBC, and there were different genomic features between two groups. Current knowledge and treatment to TP-MBC maybe inadequate and remain to be explored.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08267-9.

Integrated analysis of label-free quantitative proteomics and bioinformatics reveal insights into signaling pathways in male breast cancer

Male breast cancer (MBC) is a rare malignancy that accounts for about 1.8% of all breast cancer cases. In contrast to the high number of the “omics” studies in breast cancer in women, only recently molecular approaches have been performed in MBC research. High-throughput proteomics based methodologies are promisor strategies to characterize the MBC proteomic signatures and their association with clinico-pathological parameters. In this study, the label-free quantification-mass spectrometry and bioinformatics approaches were applied to analyze the proteomic profiling of a MBC case using the primary breast tumor and the corresponding axillary metastatic lymph nodes and adjacent non-tumor breast tissues. The differentially expressed proteins were identified in the signaling pathways of granzyme B, sirtuins, eIF2, actin cytoskeleton, eNOS, acute phase response and calcium and were connected to the upstream regulators MYC, PI3K SMARCA4 and cancer-related chemical drugs. An additional proteomic comparative analysis was performed with a primary breast tumor of a female patient and revealed an interesting set of proteins, which were mainly involved in cancer biology. Together, our data provide a relevant data source for the MBC research that can help the therapeutic strategies for its management.

Male breast cancer: A closer look at patient and tumor characteristics and factors associated with survival

Background

The prognostic effect of molecular subtypes on male breast cancer (MBC) remains unclear. The aim of this study was to evaluate the clinicopathological and prognostic factors of MBC patients.

Methods

From 1 January 1990 to 31 December 2014, the data of 152 MBC and 304 female breast cancer (FBC) patients were identified and extensively compared.

Results

Compared with the FBC group, MBC patients were found to have a higher rate of cancer family history (30.9% vs. 18.4%, P = 0.001), mass around the areola area (37.5% vs. 5.6%, P = 0.000), lymph node invasion (44.1% vs. 34.2%, P = 0.006) and hormonal receptor positivity (66.4% vs. 49.3%, P = 0.027). Luminal A was the most common subtype accounting for 69.8%, whereas HER2‐positive (12.7%) and TNBC (1.6%) subtypes were rare in the MBC group. However, it was significantly lower for MBC than for FBC who received endocrine therapy (38.8% vs. 49.3%, P = 0.041). MBC showed the worse overall survival (OS) and disease‐free survival (DFS) than those of FBC patients. However, 10‐year OS and DFS were similar between MBC and FBC patients in the subgroups of nonluminal subtype (P < 0.001), but worse in MBC patients than those in FBC patients in the subgroups of luminal A (P = 0.004 for OS; P = 0.002 for DFS) and luminal B (P = 0.006 for OS; P = 0.003 for DFS). Multivariate analysis indicated tumor size, radical mastectomy and endocrine therapy as independent risk factors for OS and DFS of MBC patients.

Conclusions

Our study determined that MBC patients possessed a worse prognosis, usually with lymph node invasion, and were estrogen receptor (ER), progesterone receptor (PR)‐positive and human epidermal growth factor receptor (HER2)‐negative. Molecular subtypes based on FBC did not provide the same prognostic information in MBC, even in the luminal groups.

Histology of Luminal Breast Cancer

Background

Invasive breast cancer (IBC) can be categorized into prognostic and predictive molecular subtypes (including luminal breast cancer) using gene expression profiling. Luminal IBC comprises a variety of histological subtypes with varying clinical and pathological features.

Summary

IBC of no special subtype is the most common histological subtype in general and likewise within luminal IBC. Classical invasive lobular breast cancer, typically clustering into luminal subgroup, is characterized by discohesive growth and loss of E-cadherin expression. Infrequent, morphologically distinct luminal IBC subtypes are tubular, invasive cribriform, mucinous, and invasive micropapillary carcinomas. Breast carcinoma with apocrine differentiation, with characteristic expression of androgen receptor (AR), often clusters into the luminal AR category. Rarely, neuroendocrine neoplasms of the breast can be seen. IBC of the male breast usually matches with the luminal subtype.

Key Messages

Independently from histological subtypes, invasive breast cancer (IBC) can be divided into molecular subtypes based on mRNA gene expression levels. Using this molecular subtyping, risk scores based on gene expression profiling (established for hormone receptor-positive, HER2-negative IBC), grading, and Ki-67 index, prognosis of patients with luminal breast cancer and response to chemotherapy can be predicted. In routine diagnostics, the expression of estrogen receptor (ER) and progesterone receptor (PR), HER2 status, and the proliferation rate (Ki-67) are used to determine a surrogate (molecular-like) subtype. Within luminal(-like) IBC, no special subtype and invasive lobular breast carcinoma are the most common histological subtypes. Other rare histological subtypes (e.g., tubular carcinoma) should be recognized due to their distinct clinical and pathological features.

Pharmacological management of male breast cancer

INTRODUCTION

Despite its rarity, male breast cancer shows a steadily rising incidence. Given the absence of ad hoc prospective randomized clinical trials, treatment strategies are based on extrapolation from female breast cancer recommendations or solely on population-based data.

AREAS COVERED

This review discusses the current treatment landscape for male breast cancer in the adjuvant and in the metastatic setting. The authors also discuss the biology and genomic landscape of male breast cancer. Original research and review articles, relative to the period 2010-2019, were included in the review of the literature.

EXPERT OPINION

There is a major medical need to include male patients with breast cancer in prospective clinical trials. The call to equality in breast cancer care can be pursued via two divergent paths: (i) a gender-neutral delivery of breast cancer information and (ii) the creation of separate sections, for the more common female breast cancer and for the rare male ones. We propose to differentiate male breast cancer care, acknowledging unique onco-sexual and social needs that can be only partially shared.

Epidemiology and biological characteristics of male breast cancer in Italy

AIM

To evaluate the epidemiology of male breast cancer (MBC) in Italy and to describe incidence and survival data in relation to age, morphology, year of incidence, geographic area, and possible association with other cancers compared with female BC.

METHODS

Cases were extracted from 40 Italian Cancer Registries. Standardized incidence rates (SIR), age-specific rates, and 5-year survival were calculated. The association with second tumors was also evaluated. All data were compared with data from female BCs.

RESULTS

In the 2000-2014 period, 2175 new cases of MBC were registered, with an SIR of 1.7 × 100,000. The incidence showed a slight upward trend and increased with increasing age. The 5-year survival was 82% in the first two periods (2000-2004, 2005-2009), lower than in females (87%). The most frequent morphology was the ductal carcinoma (84%). Stage at diagnosis was 39.5% stage I, 33.1% stage II, 20.9% in stage III, and 6.4% in stage IV. Concerning receptor status, 96.4% had ER+ and 82.5% PR+; 46.5% had high Ki67 and 14.7% HER2 amplified. The risk of BC increased if the man had already had a previous tumor in any site (excess absolute risk, EAR = 2.7) and especially if he had had prostate cancer (EAR = 5.1). Instead, males with a previous diagnosis of BC had an increased risk of testicular, kidney and lung cancer.

CONCLUSIONS

MBC requires more attention in terms of diagnosis and treatment as clinicians tend to follow the guidelines that have been developed for female BC management.

Male breast cancer: clinicopathological characterization of a National Danish cohort 1980-2009

Background

To describe relevant pathological parameters of Danish male breast cancer patients (MBCP) diagnosed from 1980 to 2009, and to relate these data to treatment, overall survival (OS) and standardized mortality rate (SMR).

Materials and methods

The MBCP cohort was defined from national Danish registers. A total of 643 MBCP were identified with tissue available in 457. Among these, 384 were primary operable. Where tissue blocks were available, tumor type, grade, estrogen receptor (ER), progesteron receptor (PgR) and androgen-receptor (AR) status as well as HER 2 and Ki67 were performed. OS was quantified by Kaplan–Meier estimates and SMR was calculated based on mortality rate among patients relative to the mortality rate in the general population.

Results

Male breast cancer was more often of ductal type, grade II and a very high proportion were ER and AR positive and HER2 negative. Intrinsic subtypes based on immunohistochemical evaluation showed luminal subtype. Ki67 ratio increased over period of study. OS declined by increased age, bigger tumor size, positive lymph node status, higher grade and Luminal B subtype. Hazard ratio and relative risk of SMR were highest for patients aged < 60 years.

Conclusion

Male breast cancer is of luminal subtype, but more often Luminal B. Ki67 is crucial in evaluation of subtypes by immunohistochemistry, but have limitations. Subtyping seems to be of major importance. AR also can have a role in future treatment.

Electronic supplementary material

The online version of this article (10.1007/s12282-020-01066-3) contains supplementary material, which is available to authorized users.

Male breast cancer: a neglected disease

Male breast cancer (MBC) is rare, tending to afflict sedentary men, with adolescent obesity being a risk factor. Men fare worse compared with matched females with breast cancer. The preponderance of ER+ve disease affects the molecular profile: most cases have luminal A tumors. Through male ignorance and risk-taking, delay is frequent and this lacuna needs addressing with health education. The major gene mutation responsible for MBC is BRCA2. Five single nucleotide polymorphisms (SNPs) are significantly and uniquely associated with MBC risk with two located in the 8q24.21 regions. Mastectomy is being gradually replaced by nipple-preserving surgery and radiotherapy but this trend could be expedited with neoadjuvant endocrine therapy. Significant advances will occur only after expansion of collaborative groups and this is a matter of pressing importance.

FDA Approval Summary: Palbociclib for Male Patients with Metastatic Breast Cancer

On April 4, 2019, the FDA approved a supplemental new drug application for palbociclib (IBRANCE), to expand the approved indications in women with hormone receptor (HR)-positive, HER2-negative advanced or metastatic breast cancer (MBC) in combination with an aromatase inhibitor or fulvestrant, to include men. Palbociclib was first approved in 2015 for use in combination with letrozole for the treatment of estrogen receptor-positive, HER2-negative advanced breast cancer as initial endocrine-based therapy in postmenopausal women and subsequently in 2016 in combination with fulvestrant in women with HR-positive, HER2-negative advanced breast cancer with disease progression following endocrine therapy. The current approval was primarily based on the results of the PALOMA-2 and PALOMA-3 trials and, supported by real-world data from electronic health records and insurance claims. To support the safety evaluation in male patients, data from two phase I studies with palbociclib and safety information from the global safety database, were also reviewed. This article summarizes FDA decision-making and data supporting the approval of palbociclib for the treatment of male patients with HR-positive, HER2-negative advanced or MBC.

Metachronous Contralateral Male Breast Cancer: Case Report and Literature Review

Male breast cancer (MBC) is rare and consequently understudied. Here we present the case of contralateral breast cancer in a male patient nearly a quarter century following his initial breast cancer diagnosis and treatment. The epidemiology, risk factors, diagnosis, characterization, treatment, and prognosis of male breast cancer are reviewed. MBC accounts for <1% of all breast cancer with an estimated incidence nearly 1.25 per 100,000 person years. Our patient tested positive for ATM mutation of undetermined significance. More commonly in males, a BRCA2 mutation confers a >1 in 15 lifetime risk of breast cancer and is present in >11% of MBC patients, while BRCA1 is present in an estimated <1.5% of MBC patients. The risk of contralateral breast cancer developing in a male with a unilateral lesion is much higher than for a primary male breast cancer in the general population. Men tend to be diagnosed at a later age and stage than females. Prognosis for male and female breast cancer is similar considering both age of patient and stage of the tumor at diagnosis, and similar treatment paradigms have resulted in similar outcomes. Although lumpectomy with radiation therapy may have the same prognosis as mastectomy, the standard of care for male breast cancer continues to be simple mastectomy with sentinel lymph node biopsy.

Characterization of male breast cancer: results of the EORTC 10085/TBCRC/BIG/NABCG International Male Breast Cancer Program

Background

Male breast cancer (BC) is rare, managed by extrapolation from female BC. The International Male BC Program aims to better characterize and manage this disease. We report the results of part I, a retrospective joint analysis of cases diagnosed during a 20-year period.

Methods

Patients with follow-up and tumor samples, treated between 1990 and 2010, in 93 centers/9 countries. Samples were centrally analyzed in three laboratories (the United Kingdom, the Netherlands and the United States).

Results

Of 1822 patients enrolled, 1483 were analyzed; 63.5% were diagnosed between 2001 and 2010, 57 (5.1%) had metastatic disease (M1). Median age at diagnosis: 68.4 years. Of 1054 M0 cases, 56.2% were node-negative (N0) and 48.5% had T1 tumors; 4% had breast conserving surgery (BCS), 18% sentinel lymph-node biopsy; half received adjuvant radiotherapy; 29.8% (neo)adjuvant chemotherapy and 76.8% adjuvant endocrine therapy (ET), mostly tamoxifen (88.4%). Per central pathology, for M0 tumors: 84.8% ductal invasive carcinomas, 51.5% grade 2; 99.3% estrogen receptor (ER)-positive; 81.9% progesterone receptor (PR)-positive; 96.9% androgen receptor (AR)-positive [ER, PR or AR Allred score ≥3]; 61.1% Ki67 expression low (<14% positive cells); using immunohistochemistry (IHC) surrogates, 41.9% were Luminal-A-like, 48.6% Luminal-B-like/HER-2-negative, 8.7% HER-2-positive, 0.3% triple negative. Median follow-up: 8.2 years (0.0-23.8) for all, 7.2 years (0.0-23.2), for M0, 2.6 years (0.0-12.7) for M1 patients. A significant improvement over time was observed in age-corrected BC mortality. BC-specific-mortality was higher for men younger than 50 years. Better overall (OS) and recurrence-free survival (RFS) were observed for highly ER+ (P = 0.001), highly PR+ (P = 0.002), highly AR+ disease (P = 0.019). There was no association between OS/RFS and HER-2 status, Ki67, IHC subtypes nor grade.

Conclusions

Male BC is usually ER, PR and AR-positive, Luminal B-like/HER2-negative. Of note, 56% patients had T1 tumors but only 4% had BCS. ER was highly positive in >90% of cases but only 77% received adjuvant ET. ER, PR and AR were associated with OS and RFS, whereas grade, Ki67 and IHC surrogates were not. Significant improvement in survival over time was observed.

Surgical options for male breast cancer

BACKGROUND

Male breast cancer (MBC) is a rare disease for which no randomised controlled trials (RCT) have been conducted to determine optimal surgical management. The available data have been reviewed to identify reasonable options and reveal areas in need of investigation.

METHODS

All published series on the surgical management of MBC have been reviewed to determine approaches to treatment of the primary, the breast and the axilla together with the psychological sequelae of surgery.

FINDINGS

Mastectomy is still the major surgical offer but a convincing case can be made for the use of neoadjuvant endocrine treatment in order to facilitate breast conserving surgery. Sentinel node biopsy has been successfully used for staging MBC although nomograms for prediction of nodal status are inadequately calibrated. There are psychological sequelae of mastectomy in males and as yet no evidence that the needs of those with MBC are being met.

CONCLUSIONS

Collaborative studies are required so that men can participate in meaningful RCTs to provide an evidence-based rational foundation for the surgery of MBC.

Magee Equation Recurrence Score Is Associated With Distal Metastatic Risk in Male Breast Carcinomas: Experience From Two Institutions

OBJECTIVES

To conduct a clinicopathologic study of male breast carcinoma with Magee equation recurrence score (RS).

METHODS

Seventy-four cases of male invasive breast cancers (MBCs) were studied, including 63 hormone receptor (HR)-positive, 10 human epidermal growth factor receptor 2-positive, and one triple-negative breast cancers.

RESULTS

Among 63 HR-positive MBC patients, nine patients developed distal metastasis. Statistical analysis demonstrated distal metastasis was significantly associated with positive lymph node, high Nottingham grade, and increased Magee equation RS. All HR-positive MBCs were further stratified into two categories (low RS <18; intermediate/high RS ≥18). There was a significantly increased risk for distal metastasis in MBCs with intermediate/high Magee equation RS, but no increased risk for lymph node metastasis.

CONCLUSIONS

Our data suggest Magee equation RS may be useful to predict distal metastatic risk in MBC patients.

Male breast cancer: a disease distinct from female breast cancer

PURPOSE

Male breast cancer (BC) is rare, representing approximately 1% of cancers that occur in men and approximately 1% of all BCs worldwide. Because male BC is rare, not much is known about the disease, and treatment recommendations are typically extrapolated from data available from clinical trials enrolling female BC patients.

METHODS

We review the epidemiology, risk factors, prognosis, and the varied molecular and clinicopathologic features that characterize male BC. In addition, we summarize the available data for the use of systemic therapy in the treatment of male BC and explore the ongoing development of targeted therapeutic agents for the treatment of this subgroup of BCs.

RESULTS

There are important biological differences between male and female BC. Male BC is almost exclusively hormone receptor positive (+), including the androgen receptor (AR), and is associated with an increased prevalence of BRCA2 germline mutations, especially in men with increased risk for developing high-risk BC. Additional research is warranted to better characterize male BC. To accomplish this, a multi-national consortium approach, such as the International Male Breast Cancer Program, is needed in response to the scarcity of patients. This approach allows the pooling of information from a large number of men with BC and the creation of registries for future therapeutic-focused clinical trials.

CONCLUSIONS

Given the unique biology of BC in men, promising new therapeutic targets are currently under investigation, including the use of poly-ADP-ribose polymerase inhibitors or AR-targeted agents either as monotherapy or in combination with other agents.

Characterising the adipose-inflammatory microenvironment in male breast cancer

Male breast cancer (MBC) incidence seems to parallel global increases in obesity. The stromal microenvironment contributes to carcinogenesis; yet, the role of adipocytes in this is understudied in MBC. We identified four cohorts of male breast tissues diagnosed when obesity was rare (archival cohort) and more common (contemporary cohort). We examined the microenvironment of archival and contemporary cohorts of MBC, diagnosed 1940-1970 and 1998-2006, respectively, with two cohorts of, archival and contemporary gynaecomastia, diagnosed 1940-1979 and 1996-2011, respectively, serving as controls. We quantified adipocytes, crown-like structures (CLS) and the presence of CD8, α smooth muscle actin (αSMA) and CD68+ macrophages in both cohorts, and determined how these affected survival, in the contemporary MBC cohort. In both MBC cohorts, mean adipocyte diameter was larger in the distant stroma compared with stroma close to the invading tumour (92.2 µm vs 66.7 µm). This was not seen in gynaecomastia. CLS were more frequent in both MBC cohorts than gynaecomastia (44/55 (80%) vs 11/18 (61%), P < 0.001). No relationship was found between CLS number and adipocyte size, although there were greater numbers of CLS in contemporary MBC > archival MBC > gynaecomastia. CD8 and CD68 expression in the stroma was significantly associated with reduced survival, with no effects seen with αSMA. Changes in the adipose-inflammatory microenvironment may be a contributing factor to the increase seen in MBC diagnosis.

Survival Comparisons Between Early Male and Female Breast Cancer Patients

We aimed to compare the overall survival (OS) and standardized mortality rate (SMR) of the male breast cancer (MBC) with female breast cancer (FBC) after propensity score matching. Based on the Surveillance, Epidemiology, and End Results (SEER), the early breast cancer patients (T1-2N0-2M0) were extracted from 1998-2007. This study included 1,111 and 2,151 patients with early MBC and FBC, respectively, whose clinicopathological characteristics were well balanced. At a mean follow-up time of 97 months, 10-year OS rate was 58.3% in the MBC group and 68.7% in the FBC (log-rank test, P < 0.001; hazard ratio (HR) = 1.45, 95% confidence interval (CI) = 1.29 to 1.64). Adjusted HR for OS between MBC and FBC were revealed from propensity score matched-multivariable Cox proportional hazards models (HR = 1.53, 95% CI = 1.35 to 1.73). Similar adjusted SMRs between MBC and FBC ((SMR = 1.98, 95% CI = 1.83,2.14) for FBC and (SMR = 2.07, 95% CI = 1.88-2.28) for MBC) were observed. The nomogram was constructed for FBC, and predicted probabilities were generally good (C-index = 0.71), whose area under curve is higher than TNM stage classification (0.74 vs 0.62). OS was significantly decreased among early MBC patients compared with FBC, but similar SMRs and its trends by age groups were observed between MBC and FBC except for young patients.

The endocrinology of male breast cancer

Male breast cancer (MBC) is a rare disease but, as a result of epidemiological collaborations, there is now greater clarity concerning endocrine risk factors. The significant rise in global age-standardised mean BMI in men is likely to lead to increases in incidence of maturity-onset diabetes and MBC. The metabolic changes accompanying obesity decrease androgens and sex hormone-binding globulin (SHBG), thereby increasing available oestrogens. The higher rates of MBC in North and Equatorial Africa are largely due to liver damage from endemic bilharziasis and hepatitis B causing elevated oestradiol (E₂) levels from hepatic conversion of androgen. Klinefelter's syndrome (XXY) is associated with a 50-fold increase in incidence of MBC compared with XY males, and this is the most pronounced evidence for testicular malfunction amplifying risk. Delay in presentation means that up to 40% of cases have stage III or stage IV disease at diagnosis. No randomised controlled trials have been reported on endocrine treatment of advanced disease or adjuvant/neoadjuvant therapy following or preceding surgery. Tamoxifen is the most effective endocrine therapy, but side effects can lead to non-compliance in a substantial number of men. Aromatase inhibitors are less effective because they do not inhibit testicular oestrogen production. There is an urgent need for collaborative trials to provide an evidence base for the most effective endocrine and least toxic therapies for men with breast cancer.

The biology of male breast cancer

Important differences have begun to emerge concerning the molecular profile of female and male breast cancer which may prove to be of therapeutic value. This review examined all the available data on the genomics of MBC. Most male cancers are ER+ve but without a corresponding increase in PR positivity and only a weaker association with estrogen-controlled markers such as PS2, HSP27 and Cathepsin-D. HER2 +ve cancers are rare in males and the role of androgen receptor is controversial. Although the Luminal A phenotype was the most frequent in both MBC and FBC, no Luminal B or HER2 phenotypes were found in males and the basal phenotype was very rare. Using hierarchical clustering in FBC, ERα clustered with PR, whereas in MBC, ERα associated with ERβ and AR. Based on limited data it appears that Oncotype DX is effective in determining recurrence risk in selected MBC. In future, tailored therapies based on genomics will probably yield the most promising approach for both MBC and FBC.