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

Predicting Overall Survival in Patients with Male Breast Cancer: Nomogram Development and External Validation Study

Background

Male breast cancer (MBC) is an uncommon disease. Few studies have discussed the prognosis of MBC due to its rarity.

Objective

This study aimed to develop a nomogram to predict the overall survival of patients with MBC and externally validate it using cases from China.

Methods

Based on the Surveillance, Epidemiology, and End Results (SEER) database, male patients who were diagnosed with breast cancer between January 2010, and December 2015, were enrolled. These patients were randomly assigned to either a training set (n=1610) or a validation set (n=713) in a 7:3 ratio. Additionally, 22 MBC cases diagnosed at the First Affiliated Hospital of Guangxi Medical University between January 2013 and June 2021 were used for external validation, with the follow-up endpoint being June 10, 2023. Cox regression analysis was performed to identify significant risk variables and construct a nomogram to predict the overall survival of patients with MBC. Information collected from the test set was applied to validate the model. The concordance index (C-index), receiver operating characteristic (ROC) curve, decision curve analysis (DCA), and a Kaplan-Meier survival curve were used to evaluate the accuracy and reliability of the model.

Results

A total of 2301 patients with MBC in the SEER database and 22 patients with MBC from the study hospital were included. The predictive model included 7 variables: age (hazard ratio [HR] 1.89, 95% CI 1.50-2.38), surgery (HR 0.38, 95% CI 0.29-0.51), marital status (HR 0.75, 95% CI 0.63-0.89), tumor stage (HR 1.17, 95% CI 1.05-1.29), clinical stage (HR 1.41, 95% CI 1.15-1.74), chemotherapy (HR 0.62, 95% CI 0.50-0.75), and HER2 status (HR 2.68, 95% CI 1.20-5.98). The C-index was 0.72, 0.747, and 0.981 in the training set, internal validation set, and external validation set, respectively. The nomogram showed accurate calibration, and the ROC curve confirmed the advantage of the model in clinical validity. The DCA analysis indicated that the model had good clinical applicability. Furthermore, the nomogram classification allowed for more accurate differentiation of risk subgroups, and patients with low-risk MBC demonstrated substantially improved survival outcomes compared with medium- and high-risk patients (P<.001).

Conclusions

A survival prognosis prediction nomogram with 7 variables for patients with MBC was constructed in this study. The model can predict the survival outcome of these patients and provide a scientific basis for clinical diagnosis and treatment.

HER2 expression and pathway status in male breast cancer patients: results of an integrated analysis among 6,150 patients

The role of human epidermal growth factor 2 (HER2) in male breast cancer (MBC) is poorly defined. A comprehensive description of HER2 status was conducted. A total of 6,015 MBC patients from 45 studies and 135 MBC patients with sequencing data were identified. HER2 positive rates and hazard ratios (HR) for overall survival (OS) were combined using Metaprop. The prevalence of HER2 + MBC was 10.0% (95% CI: 8.0-13.0%). Subgroup analyses showed that 7% (95% CI: 2.0-14.0%) had HER2 + protein overexpression. 10% of MBC patients had HER2 + overexpression and/or gene amplification. Asian MBC patients had the highest HER2 + incidence of 17% (95% CI: 12.0-22.0%). The prevalence of HER2 positive MBC fluctuated widely from 2001 to 2015 and then stabilized at 10%. HER2 positivity was significantly correlated with worse OS than negative ones (HR = 1.92, 1.47-2.51). The proportion of HER2 + MBC was inconsistent with the results for the intrinsic HER2-enriched subtype. Altered genes in HER2 + MBC, such as ERBB2, AGO2, RECQL4, and CLTC, were not detected in HER2-MBC. Genomic analysis revealed differences between the patients with HER2 + MBC and those with HER2 + FBC. The percentage of HER2 + MBC was slightly lower than that of women. Multiple approaches may be needed to jointly assess HER2 status in MBC.

The role of radiation therapy in the multidisciplinary management of male breast cancer: A systematic review and meta-analysis on behalf of the Clinical Oncology Breast Cancer Group (COBCG)

Male breast cancer (MaBC) is an uncommon disease. It is generally assimilated to post-menopausal female breast cancer and treated accordingly. However, the real impact of radiation therapy, after both mastectomy and breast conservation, has yet to be established. We performed a systematic review and meta-analysis to assess the clinical impact of radiation therapy in MBC patients to support the clinical decision-making process and to inform future research. We performed a systematic search of 'male', 'breast', 'cancer', 'radiotherapy' and corresponding synonyms on PubMed/MEDLINE and EMBASE databases. We included interventional studies reporting on radiation therapy effect on overall survival (OS) in MBC patients. Reviews, editorials, letters to the editor, conference abstracts and case reports, and studies with less than 20 MaBC patients or without data on OS were excluded. We extracted relevant characteristics and outcomes for each study, including the hazard ratio (HR) for OS, after adjustment for potential confounders. We calculated an overall adjusted hazard ratio (aHR) for OS for patients receiving radiation therapy compared to those who did not. A random effect model was used. The search strategy yielded 10,260 articles. After removal of duplicates (n = 8254), 2006 articles remained and underwent abstract screening. A total of 168 manuscripts was selected for full text screening. After full text screening, 22 articles were included in the qualitative systematic review. Among them, 14 were included in the quantitative synthesis, reporting on 80.219 MaBC patients. A statistically significant reduction in the risk of death was observed for patients receiving radiation therapy, with a pooled aHR = 0.73 (95 %CI: 0.66-0.81) for OS. Significant heterogeneity among reported aHR estimates was seen (I2=77 %). A significant clinical benefit on OS has been observed when including radiation therapy in the therapeutic algorithm of patients with MaBC. These findings, which are based on retrospective studies and tumour registry reports, deserve further investigation to identify MaBC patient subgroups who most benefit from radiation therapy.

Influence of tumour grade on disease survival in male breast cancer patients: a systematic review

PURPOSE

Histological grading of tumours is a well-established biomarker used to guide treatment in female breast cancer. However, its significance in male breast cancer remains unclear. This systematic review investigates the prognostic significance of tumour grade in relation to breast cancer-specific survival (BCSS) in male breast cancer patients undergoing surgery.

METHODS

MEDLINE, PUBMED Central and EMBASE databases were searched to identify randomised trials and observational studies related to male breast neoplasms, tumour grading, recurrence, and survival.

RESULTS

A total of fifteen observational type studies were included in the review. A significant association between tumour grade and BCSS was reported in a majority of studies. This association was most evident with regard to high-grade (grade III) compared to low grade (grade I) tumours, with a significant relationship in 4 out of 4 studies. For intermediate-grade II tumours an association was demonstrated in a minority of studies.

CONCLUSIONS

This study confirms an association between high-grade male breast cancers and poorer disease-specific survival, however, the significance of intermediate-grade tumours remains unclear. Further research is required to investigate the biology of male breast cancer in relation to histological grade and optimally define intermediate-grade disease.

HER2 Low Expression in Primary Male Breast Cancer

Purpose

The introduction of HER2-targeting antibody drug conjugates (ADCs) offers new treatment options for female breast cancer patients (FBC) expressing low levels of HER2 (HER2 low). No evidence was found that HER2 low describes a new FBC subtype. There is a lack of studies determining the impact of HER2 low in male breast cancer (MBC). In this study, we evaluate the prevalence of HER2 low in primary MBC and correlate the results with patient characteristics.

Patients and Methods

In this study, histological specimens were obtained from 120 male patients diagnosed and treated for primary invasive breast cancer from 1995 to 2022 at Breast Cancer Units in Bergisch Gladbach, Chemnitz, and Zwickau, Germany. HER2 immunostaining and in situ hybridization were performed by central pathology and evaluated based on the ASCO/CAP guidelines. The correlation of expression of HER2 low with tumor biological characteristics and patient outcomes was investigated.

Results

Out of all cases, four patients (3.3%) showed HER2 positivity (3+), 39 (32.5%) patients were classified as HER2 low, 7 (5.8%) were HER2 2+ (no amplification), 32 (26.7%) were HER2 1+, and 77 (64.2%) were classified as HER2 zero. Out of 77 HER2 zero cases, 47 tumors (61.0%) showed incomplete staining, with <10% of tumor cells classified as HER2 ultralow. No statistical correlation between HER2 low and tumor biological characteristics and patients' survival was found.

Conclusion

Our findings show a notable, albeit lower, prevalence of HER2 low expression in primary MBC. However, tumors expressing HER2 low do not show specific tumor biological features to define a new breast cancer subtype in MBC. Our results suggest that a significant number of MBC patients could benefit from ADCs, as shown in FBC. Further studies are required to better understand HER2 low breast cancer, both generally and in MBC.

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.

HR+/HER2- de novo metastatic breast cancer: a true peculiar entity?

De novo metastatic breast cancer (dnMBC) accounts for ~6-10% of all breast cancers and for ~30% of MBC with increasing incidence over time. Hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR⁺/HER2^-) tumours are the most frequent subtype with a similar incidence to that observed amongst recurrent MBC (rMBC). Higher frequency of PI3KCA and ARID2 mutations and a lower frequency of ESR1 mutations and of genes involved in DNA damage, as compared with rMBC, have been reported in HR⁺/HER2^- dnMBC; however, these are not correlating with prognosis, whilst tumour mutational burden is inversely correlated with outcome. Bone represents the most frequent metastatic site, being the single site in up to 60% of patients with dnMBC. HR⁺/HER2^- dnMBC has been generally reported to have better outcomes than rMBC, with a median overall survival ranging from 26 months to nearly 5 years in patients with favourable features such as age <40 years and bone-only disease, but not when compared with patients with late recurring disease (≥2-5 years). Analyses of the de novo cohorts within randomized clinical trials and large real-world series report a better outcome after treatment with CDK4/6 inhibitors and endocrine agents as compared to rMBC. Despite the limitations of retrospective studies and controversial results of the randomized trials, locoregional treatment of the primary tumour after response to systemic therapy appears to confer a survival benefit, particularly in patients with favourable prognostic factors. Altogether genomic, biological and clinical findings highlight HR⁺/HER2^- dnMBC as a peculiar entity as compared with rMBC and deserve a dedicated treatment algorithm. This article is part of the Tackling clinical complexity in breast cancer Special Issue: https://www.drugsincontext.com/special_issues/tackling-clinical-complexity-in-breast-cancer/.

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.

Endocrine adherence in male versus female breast cancer: a seer-medicare review

PURPOSE

Breast cancer in men (BC-M) is almost exclusively hormone receptor positive. We conducted a large review of the SEER-Medicare linked database to compare endocrine therapy adherence, discontinuation, and survival outcomes of male versus female patients with breast cancer.

METHODS

Study data were obtained through the SEER-Medicare linked database. The study included patients age ≥ 65 years-old diagnosed with breast cancer between 2007 and 2015. The primary endpoints were rates of adherence and discontinuation of endocrine therapy (ET). Adherence was defined as a gap of less than 90 days in-between consecutive Medicare prescriptions. Discontinuation was defined as a gap of greater than 12 months in-between Medicare prescriptions. Secondary endpoint was the association of use of ET with overall survival (OS).

RESULTS

Of the 363 male patients on ET, 214 patients (59.0%) were adherent to the therapy, and 149 patients (41.0%) were nonadherent. Of the 20,722 females on ET, 10,752 (51.9%) were adherent to the therapy, and 9970 (48.1%) were nonadherent. 39 male patients (10.7%) discontinued therapy, while 324 (89.3%) did not discontinue therapy. 1849 female patients (8.9%) discontinued therapy, while 18,873 (91.1%) patients did not. Men were significantly more adherent than women (p = 0.008), but there was no significant difference in discontinuation among men and women (p = 0.228). Survival was significantly improved in both men (HR 0.77, 95% CI 0.60-0.99, p = 0.039) and women (HR 0.84, 95% CI 0.81-0.87, p < 0.001) on ET.

CONCLUSION

Identification of contributing factors impacting adherence and discontinuation is needed to allow physicians to address barriers to long term use of ET.

Prognostic difficulties of men with breast cancer

Most adequately powered studies confirm a worse prognosis for males versus matched females with breast cancer. There is in-stage migration for stage I cancers with a different ratio of tumor/normal breast tissue in males. Younger men have a better prognosis, largely the result of increased morbidity in the elderly, exacerbated by smoking, low socioeconomic differences, and ethnic disparity. BRCA2 carriers with MBC have a worse outcome than noncarriers as do men with amplification of EMSY. Men with tumors having a high cytosol level of plasminogen activator inhibitor 1 (PAI-1) may have more invasive cancers leading to earlier spread and hence a worse outcome. PREDICT+ is a useful prognostic model for MBC and multigene testing enables more specific systemic therapies to be used.

Prognostic relevance of Ki67 expression in primary male breast cancer: determination of cut-off points by different evaluation methods and statistical examinations

PURPOSE

1% of all breast cancer cases occur in men. There are significant differences regarding clinical behaviour and genetic profiles between female (FBC) and male breast cancer (MBC). Parameters for decision-making on treatment and prognosis are derived from FBC. Ki67 has a high value as a prognostic and predictive factor in FBC, but accurate Ki67 cut-off points for MBC are missing. In this study, we aimed to evaluate adequate examination methods and reliable cut-off points for Ki67 to assess the highest prognostic value for patient's overall survival (OS).

METHODS

In this multicentric retrospective study, histological specimens were obtained from 104 male patients who were diagnosed and treated for primary invasive breast cancer. We applied three methods of Ki67 analysis: Tumor average scoring (TA), tumor border scoring (TB) and hot-spot scoring (HS). Calculated Ki67 cut-off points for each method were assessed as a threshold for patients' overall survival (OS).

RESULTS

Ki67 cut-off points were 13.5 for the TA group, 22.5 for the HS group and 17.5 for the TB group. Only Ki67 TA cut-off calculations demonstrated statistical significance (p = 0.04). Ki67 expression analysis of TA showed that more than 90% of patients with low Ki67 levels (< 13.5) were alive after 5-year follow-up.

CONCLUSION

Our findings demonstrate that determination of Ki67 expression in TA is the most reliable to define a cut-off point with high prognostic value. A Ki67 cut-off point of 13.5 shows highest statistical power to define luminal A subgroup and OS.

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.

Genetic testing results in Slovenian male breast cancer cohort indicate the BRCA2 7806-2A > G founder variant could be associated with higher male breast cancer risk

PURPOSE

To analyze the prevalence of pathogenic/likely pathogenic variants (P/LPVs) in BRCA1 and BRCA2 genes in the largest cohort of Slovenian male breast cancer (MBC) patients to date and to explore a possible correlation between the Slovenian founder variant BRCA2:c.7806-2A > G and predisposition to MBC.

METHODS

We performed a retrospective analysis of 81 MBC cases who underwent genetic counseling and/or testing between January 1999 and May 2020. To explore a possible genotype-phenotype correlation, we performed additional analyses of 203 unrelated families with P/LPVs in BRCA2 and 177 cases of female breast cancer (FBC) in carriers of P/LPVs in BRCA2.

RESULTS

Detection rate of P/LPVs in the BRCA1 and BRCA2 genes was 24.7% (20/81) with 95% of them in BRCA2 gene. The only two recurrent P/LPVs were BRCA2:c.7806-2A > G and BRCA2:c.3975_3978dupTGCT (9 and 5 MBC cases, respectively). In families with BRCA2:c.7806-2A > G, the incidence of MBC cases was higher compared to families with other P/LPVs in BRCA2; however, the difference did not reach statistical significance (17.8% vs. 8.9%, p = 0.105). BRCA2:c.7806-2A > G was detected in both families with multiple cases of MBC. This splice-site variant represented a significantly higher proportion of all BRCA2 P/LPVs detected in MBC carriers compared to FBC carriers (47.4% vs. 26%, p = 0.049).

CONCLUSION

We observed a high mutation detection rate and conclude this may be due to the prevalent BRCA2:c.7806-2A > G variant in Slovenia. Our results indicate a possible association between this variant and higher risk of breast cancer in males compared to other identified P/LPVs in BRCA2.

Sex-Based Heterogeneity in the Clinicopathological Characteristics and Prognosis of Breast Cancer: A Population-Based Analysis

Purpose

To better understand the differences in clinicopathological features and prognosis between male breast cancer (MBC) and female breast cancer (FBC).

Material and Methods

Data on patients diagnosed with breast cancer from January 1, 2010, to December 31, 2016, were obtained from the Surveillance, Epidemiology, and End Results database. Selected patients were classified into MBC and FBC, of which population demographics and clinicopathological features at baseline were successively extracted for analysis. Comparative analysis was performed to explore the differences in baseline characteristics, followed by propensity-score matching to calibrate the objective distinctions for adjusted analysis. Survival analysis was carried out to investigate divergences presented in prognosis from the two cohorts, and risk factors for prognosis were successively identified using univariate and multivariate COX regression analyses.

Results

A total of 407341 individuals were eligible, including 3111 MBC (0.7%) and 404230 FBC (99.3%) patients. Comparatively, patients with MBC tended to be older at diagnosis, with a higher confirmation of ductal carcinoma, a higher histological grade, a higher TNM stage, a higher proportion of luminal-like subtype, a higher rate of lung metastasis, a lower incidence of liver involvement, and a lower rate of surgical, radiation, and chemotherapeutic delivery. The overall prognosis of MBC was significantly worse than that of FBC, with a decreasing divergence both in median overall survival (65.5 months vs. 72.7 months, P<0.0001) and median breast cancer-specific survival (75.4 months vs. 77.8 months, P<0.0001). However, these discrepancies were not consistent among patients from different subgroups stratified by molecular subtype, age at diagnosis, or disease stage.

Conclusion

In this study, sex-based heterogeneity in clinicopathological characteristics and prognostic profiles was observed in the overall population of patients with breast cancer and was significantly variable among different subgroups. A male-specific design with reasonable endpoints for a clinical trial protocol will be warranted in the future.