Prospective evaluation of risk factors for male breast cancer

Second Primary Cancer Risks After Breast Cancer in BRCA1 and BRCA2 Pathogenic Variant Carriers

PURPOSE

Second primary cancer (SPC) risks after breast cancer (BC) in BRCA1/BRCA2 pathogenic variant (PV) carriers are uncertain. We estimated relative and absolute risks using a novel linkage of genetic testing data to population-scale National Disease Registration Service and Hospital Episode Statistics electronic health records.

METHODS

We followed 25,811 females and 480 males diagnosed with BC and tested for germline BRCA1/BRCA2 PVs in NHS Clinical Genetics centers in England between 1995 and 2019 until SPC diagnosis, death, migration, contralateral breast/ovarian surgery plus 1 year, or the 31st of December 2020. We estimated standardized incidence ratios (SIRs) using English population incidences, hazard ratios (HRs) comparing carriers to noncarriers using Cox regression, and Kaplan-Meier 10-year cumulative risks.

RESULTS

There were 1,840 BRCA1 and 1,750 BRCA2 female PV carriers. Compared with population incidences, BRCA1 carriers had elevated contralateral BC (CBC; SIR, 15.6 [95% CI, 11.8 to 20.2]), ovarian (SIR, 44.0 [95% CI, 31.4 to 59.9]), combined nonbreast/ovarian (SIR, 2.18 [95% CI, 1.59 to 2.92]), colorectal (SIR, 4.80 [95% CI, 2.62 to 8.05]), and endometrial (SIR, 2.92 [95% CI, 1.07 to 6.35]) SPC risks. BRCA2 carriers had elevated CBC (SIR, 7.70 [95% CI, 5.45 to 10.6]), ovarian (SIR, 16.8 [95% CI, 10.3 to 26.0]), pancreatic (SIR, 5.42 [95% CI, 2.09 to 12.5]), and combined nonbreast/ovarian (SIR, 1.68 [95% CI, 1.24 to 2.23]) SPC risks. Compared with females without BRCA1/BRCA2 PVs on testing, BRCA1 carriers had elevated CBC (HR, 3.60 [95% CI, 2.65 to 4.90]), ovarian (HR, 33.0 [95% CI, 19.1 to 57.1]), combined nonbreast/ovarian (HR, 1.45 [95% CI, 1.05 to 2.01]), and colorectal (HR, 2.93 [95% CI, 1.53 to 5.62]) SPC risks. BRCA2 carriers had elevated CBC (HR, 2.40 [95% CI, 1.70 to 3.40]), ovarian (HR, 12.0 [95% CI, 6.70 to 21.5]), and pancreatic (HR, 3.56 [95% CI, 1.34 to 9.48]) SPC risks. Ten-year cumulative CBC, ovarian, and combined nonbreast/ovarian cancer risks were 16%/6.3%/7.8% (BRCA1 carriers), 12%/3.0%/6.2% (BRCA2 carriers), and 3.6%/0.4%/4.9% (noncarriers). Male BRCA2 carriers had higher CBC (HR, 13.1 [95% CI, 1.19 to 146]) and prostate (HR, 5.61 [95% CI, 1.96 to 16.0]) SPC risks than noncarriers.

CONCLUSION

Survivors of BC carrying BRCA1 and BRCA2 PVs are at high SPC risk. They may benefit from enhanced surveillance and risk-reduction measures.

Male and female disparities in breast cancer epidemiology: A comparative cross-sectional analysis of a Brazilian cohort (2017-2021)

Male breast cancer (MBC) is a rare condition, accounting for approximately 1 % of all breast cancer cases. Nevertheless, the paucity of MBC-specific research has impeded a thorough understanding of MBC. In this study, we aimed to delineate the epidemiological implications of MBC in Brazil and benchmarked it against female breast cancer (FBC). This retrospective study analyzed data from the DATASUS database (2017-2021), which assessed the incidence of breast cancer in both sexes. All statistical analyses were performed using descriptive statistics and inferential methods, with significance set at a 95 % confidence interval. We identified 4,326 (1.7 %) and 233,793 (94.2 %) patients with MBC and FBC, respectively, in Brazil. Despite the general population concentration in the Southeast, MBC cases were more prevalent in the Northeast (p < 0.0004). At breast cancer diagnosis, males were typically older (mean age 59.5 [±10.2] years) than females (mean age 55.7 7 [±9.8] years). MBC was more commonly diagnosed clinically compared with FBC, which was most commonly diagnosed via screening. Surgical diagnostics were twice as likely in males, who also more frequently presented with advanced disease stages (stages III and IV; 72.8 % vs. 59.3 %), leading to a higher rate of mastectomy. Treatment was initiated earlier in males than in females. Although MBC comprises a minority of breast cancer cases, it is more frequently diagnosed at an advanced stage compared with FBC and necessitates aggressive treatment. Our study also underscores the potential benefit of prompt initiation of therapy and need for tailored clinical approaches in patients with MBC.

Trends in incidence, prevalence, and survival of breast cancer in the United Kingdom from 2000 to 2021

Breast cancer is the most frequently diagnosed cancer in females globally. However, we know relatively little about trends in males. This study describes United Kingdom (UK) secular trends in breast cancer from 2000 to 2021 for both sexes. We describe a population-based cohort study using UK primary care Clinical Practice Research Datalink (CPRD) GOLD and Aurum databases. There were 5,848,436 eligible females and 5,539,681 males aged 18+ years, with ≥ one year of prior data availability in the study period. We estimated crude breast cancer incidence rates (IR), prevalence and survival probability at one-, five- and 10-years after diagnosis using the Kaplan-Meier method. Analyses were further stratified by age. Crude IR of breast cancer from 2000 to 2021 was 194.4 per 100,000 person-years for females and 1.16 for males. Crude prevalence in 2021 was 2.1% for females and 0.009% for males. Both sexes have seen around a 2.5-fold increase in prevalence across time. Incidence increased with age for both sexes, peaking in females aged 60-69 years and males 90+ . There was a drop in incidence for females aged 70-79 years. From 2003-2019, incidence increased > twofold in younger females (aged 18-29: IR 2.12 in 2003 vs. 4.58 in 2018); decreased in females aged 50-69 years; and further declined from 2015 onwards in females aged 70-89 years. Survival probability for females after one-, five-, and ten-years after diagnosis was 95.1%, 80.2%, and 68.4%, and for males 92.9%, 69.0%, and 51.3%. Survival probability at one-year increased by 2.08% points, and survival at five years increased by 5.39% from 2000-2004 to 2015-2019 for females, particularly those aged 50-70 years. For males, there were no clear time-trends for short-term and long-term survival probability. Changes in incidence of breast cancer in females largely reflect the success of screening programmes, as rates rise and fall in synchronicity with ages of eligibility for such programmes. Overall survival from breast cancer for females has improved from 2000 to 2021, again reflecting the success of screening programmes, early diagnosis, and improvements in treatments. Male breast cancer patients have worse survival outcomes compared to females, highlighting the need to develop male-specific diagnosis and treatment strategies to improve long-term survival in line with females.

Pleomorphic/solid lobular carcinoma of male breast with PALB2 germline mutation: case report and literature review

Male breast cancer (MBC) accounts for approximately 1% of all breast cancers and among these infiltrating lobular carcinomas (ILC) represents only 1-2% of all MBC cases. Pleomorphic invasive lobular carcinoma (PILC) is an aggressive variant of ILC with only eight cases reported until now in males. Up to 10% of MBC cases have a germline pathogenic variant in a predisposing gene such as BRCA1 and BRCA2 genes. Mutations in PALB2 (partner and localizer of BRCA2) have been reported in men with breast cancer, with a frequency that ranges from 0.8 to 6.4%, but it has never been reported in male ILC. Here, we report a rare and interesting case of an invasive pleomorphic/solid lobular carcinoma, which carries a pathogenic variant in PALB2 gene, and a family history of breast cancer without other well defined risk factors for developing this type of neoplasia. In addition, we review the current literature.

Male Breast Cancer: a Review on Diagnosis, Treatment, and Survivorship

PURPOSE OF REVIEW

Male breast cancer is a relatively uncommon and rare disease that is often managed based on evidence adopted from trials pertaining to female breast cancer due to low accrual rates or exclusion of males. This is despite the known differences in the biology and epidemiology of this condition. This review provides an update regarding the management and surveillance of male breast cancer.

RECENT FINDINGS

Men with breast cancer tend to undergo more extensive surgery in the breast and axilla. The outcomes of male breast cancer compared to a similar subtype of female breast cancer appear worse when matched for stage. Systemic therapies remain predominantly based on recommendations for female breast cancer, although tamoxifen is the more optimal endocrine therapy for men than women. Surveillance with mammograms is recommended for patients harboring a breast cancer susceptibility gene but is otherwise not advised for men who have undergone a mastectomy. Notably, the role of other imaging modalities, including ultrasound and magnetic resonance imaging, is minimal. Although the focus on survivorship care among men is low, it is abundantly clear that this is a stigmatizing diagnosis for men, and they suffer from long-term physical and psychological sequelae following a diagnosis and treatment of breast cancer. In summary, providing more gender-inclusive care and advocating for increased representation of men in prospective breast cancer studies and clinical trials may help improve outcomes and provide enhanced support for this population.

Establishment of Prognostic Nomogram for Male Breast Cancer Patients: A Surveillance, Epidemiology and End Results Database Analysis

BACKGROUND

Male breast cancer (MBC) represents a rare subtype of breast cancer, with limited prognostic factor studies available. The purpose of this research was to develop a unique nomogram for predicting MBC patient overall survival (OS) and breast cancer-specific survival (BCSS).

METHODS

From 2010 to 2020, clinical characteristics of male breast cancer patients were obtained from the Surveillance, Epidemiology and End Results (SEER) database. Following univariate and multivariate analyses, nomograms for OS and BCSS were created. Kaplan-Meier plots were further generated to illustrate the relationship between independent risk variables and survival. The nomogram's ability to discriminate was measured by employing the area under a time-dependent receiver operating characteristic curve (AUC) and calibration curves. Additionally, when the nomogram was used to direct clinical practice, we also used decision curve analysis (DCA) to evaluate the clinical usefulness and net clinical benefits.

RESULTS

A total of 2143 patients were included in this research. Univariate and multivariate analysis showed that age, grade, surgery, chemotherapy status, brain metastasis status, subtype, marital status, race, and AJCC-T, AJCC-N, and AJCC-M stages were significantly correlated with OS. Lung metastasis, age, marital status, grade, surgery, and AJCC-T, AJCC-N, and AJCC-M stages were significantly correlated with BCSS. By comprising these variables, a predictive nomogram was constructed in the SEER cohort. Then, it could be validated well in the validation cohort by receiver operating characteristics (ROCs) curve and calibration plot. Furthermore, the nomogram demonstrated better decision curve analysis (DCA) results, indicating the ability to forecast survival probability with greater accuracy.

CONCLUSION

We created and validated a unique nomogram that can assist clinicians in identifying MBC patients at high risk and forecasting their OS/BCSS.

Multigene Panel Sequencing Identifies a Novel Germline Mutation Profile in Male Breast Cancer Patients

Even though male breast cancer (MBC) risk encompasses both genetic and environmental aetiologies, the primary risk factor is a germline pathogenic variant (PV) or likely pathogenic variant (LPV) in BRCA2, BRCA1 and/or PALB2 genes. To identify new potential MBC-specific predisposition genes, we sequenced a panel of 585 carcinogenesis genes in an MBC cohort without BRCA1/BRCA2/PALB2 PV/LPV. We identified 14 genes carrying rare PVs/LPVs in the MBC population versus noncancer non-Finnish European men, predominantly coding for DNA repair and maintenance of genomic stability proteins. We identified for the first time PVs/LPVs in PRCC (pre-mRNA processing), HOXA9 (transcription regulation), RECQL4 and WRN (maintenance of genomic stability) as well as in genes involved in other cellular processes. To study the specificity of this MBC PV/LPV profile, we examined whether variants in the same genes could be detected in a female breast cancer (FBC) cohort without BRCA1/BRCA2/PALB2 PV/LPV. Only 5/109 women (4.6%) carried a PV/LPV versus 18/85 men (21.2%) on these genes. FBC did not carry any PV/LPV on 11 of these genes. Although 5.9% of the MBC cohort carried PVs/LPVs in PALLD and ERCC2, neither of these genes were altered in our FBC cohort. Our data suggest that in addition to BRCA1/BRCA2/PALB2, other genes involved in DNA repair/maintenance or genomic stability as well as cell adhesion may form a specific MBC PV/LPV signature.

Breast Cancer Screening in Men

Breast cancer screening has been highly successful in women in reducing mortality through early detection. In comparison, clinical detection of breast cancer remains the norm in men, and delay in diagnosis is reflected by a persistent survival disparity compared to women despite advances in modern therapy. Male breast cancer presents an interesting dilemma. While mammography is highly sensitive and specific for male breast cancer, routine screening is not justified by the overall low disease incidence. Yet there has been interest in leveraging mammography in targeted screening of men with identifiable risk factors to allow early detection, and early data may support this approach. The purpose of this article is to explore the potential utility of targeted breast cancer screening in men by examining unique clinical and biologic characteristics of male breast cancers that may lend themselves to mammographic detection. We will also discuss available evidence in screening outcomes in men and summarize recent updates in risk management recommendations in Society guidelines.

Orbital Metastases of Breast Cancer in Males

We report a case of orbital metastasis of infiltrative breast carcinoma in a 65-year-old man. The patient was diagnosed with stage four breast cancer one year before, for which a mastectomy was performed. He refused postoperative radiotherapy and chemotherapy at that time. He had a history of lung, liver, and mediastinal metastases. At admission, he presented with blurred vision, diplopia, ocular pain, and mild swelling of the upper lid of the left eye (LE). Computed tomography (CT) of the brain and orbit revealed a front-ethmoidal tissue mass with left orbital and frontal intracranial extension. Ophthalmologic examination revealed exophthalmos on the LE with a downward and outward deviation of the eyeball, proptosis, and intraocular pressure (IOP) of 40 mmHg. The patient's treatment started with topical maximal anti-glaucomatous drops and radiotherapy sessions. After three weeks of follow-up, there was a gradual improvement of local symptoms and signs and a normal IOP.

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.

Dietary and physical activity changes and adherence to WCRF/AICR cancer prevention recommendations following a remotely delivered weight loss intervention for female breast cancer survivors: The Living Well after Breast Cancer randomized controlled trial

BACKGROUND

Diet, exercise, and weight management are key in improving outcomes for breast cancer survivors, with international recommendations for cancer survivors relating to these behaviors. However, few behavioral interventions have reported outcomes aligned specifically with these recommendations.

OBJECTIVE

To evaluate a remotely delivered weight loss intervention versus usual care for female breast cancer survivors, on changes in multiple diet and physical activity behaviors.

DESIGN

A randomized controlled trial with assessments at study baseline, 6-, 12- and 18 months (i.e., mid-intervention, post-intervention, and non-contact follow-up).

PARTICIPANTS/SETTING

Participants were recruited between October 2012 and December 2014 through hospitals in Brisbane (Australia) and the state-based cancer registry. Eligible participants (female, 18-75 years, BMI 25-45 kg/m², diagnosed with stage I-III breast cancer in previous two years) were randomly allocated to intervention (n=79) or usual care (n=80).

INTERVENTION

Participants randomized to the intervention group received 22 counseling telephone calls targeting diet and physical activity aimed at achieving 5-10% weight loss, and optional text messages, over 12 months. Usual care participants received their standard medical care and brief feedback following each assessment, which was similar to that provided to intervention participants with the exception that usual care participants' results were not compared to national and study recommendations.

MAIN OUTCOME MEASURES

Dietary intake (24-hour recalls); physical activity (hip-worn Actigraph); sitting time (thigh-worn activPAL3); and, adherence to World Cancer Research Fund/American Cancer Research Institute (WCRF/AICR) recommendations for cancer survivors (0-7 score) were measured at each assessment, with data collected between November 2012 and October 2016.

STATISTICAL ANALYSES PERFORMED

Intervention effects were assessed by linear mixed models, accounting for repeated measures and baseline values. Significance was set at P<0.05.

RESULTS

At baseline, participants were (mean±SD) aged 55±9 years, with a BMI of 31.4±5.0 kg/m², 10.7±5.0 months post-diagnosis, and primarily non-minority. At baseline, only 8% (n=12) of participants met ≥5/7 WCRF/AICR recommendations (mean±SD WCRF/AICR adherence score: 3.8±1.0). At 12 months, significant intervention effects were observed in walking/running ( +21 mins/week; 95%CI: 4, 38) and WCRF/AICR adherence scores (+0.3 points; 95%CI: 0.0, 0.6) only. At 18 months, significant intervention effects were observed for energy intake (-229 kcal/day energy; 95%CI: -373, -84), total fat (-10 g/day; 95%CI: -18, -2), and saturated fat (-5 g/day; 95%CI: -9, -1), and were sustained for WCRF/AICR adherence scores (+0.5 points; 95%CI: 0.2, 0.8).

CONCLUSIONS

This remotely delivered weight loss intervention led to sustained improvements in WCRF/AICR adherence scores, and some improvements in diet and physical activity. These findings provide support for the health benefit of programs targeting lifestyle behaviors in line with cancer survivor recommendations, and the potential for dissemination of such programs following treatment for early-stage female breast cancer.

18F-FDG PET/CT for the evaluation of male breast cancer: a systematic review

BACKGROUND

In the last years, some studies on the usefulness of 18F-fluorodeoxyglucose PET/computed tomography (18F-FDG PET/CT) for the evaluation of male breast cancer (MBC) have been produced. The aim of this review is to analyze the usefulness of 18F-FDG PET/CT and its diagnostic performances for the assessment of MBC.

METHODS

A wide literature search of the PubMed/MEDLINE, Scopus, Embase and Cochrane library databases was made to find relevant published articles on the role of 18F-FDG PET/CT for the evaluation of MBC. Moreover, quality assessment including the risk of bias and applicability concerns was carried out using QUADAS-2 evaluation.

RESULTS

The comprehensive computer literature search revealed 3178 articles. On reviewing the titles and abstracts, 3170 articles were excluded because the reported data were not within the field of interest and finally eight studies were included in the review, for a total of 176 male patients. The studies considered revealed high diagnostic accuracy of 18F-FDG PET/CT for the evaluation of MBC both at staging and restaging of disease. Moreover, its added values compared to conventional imaging are starting to emerge and insight into its controversial prognostic importance is growing.

CONCLUSION

Despite some limitations affecting our review, 18F-FDG PET/CT seems to be a valuable tool to assess MBC. Further research studies are required to better underline the role of hybrid imaging with 18F-FDG for the evaluation of MBC, especially in comparison with female breast cancer.

Risk of breast cancer in men in relation to weight change: a national case‐control study in England and Wales

Breast cancer is uncommon in men and knowledge about its causation limited. Obesity is a risk factor but there has been no investigation of whether weight change is an independent risk factor, as it is in women. In a national case‐control study, 1998 men with breast cancer incident in England and Wales during 2005 to 2017 and 1597 male controls were interviewed about risk factors for breast cancer including anthropometric factors at several ages. Relative risks of breast cancer in relation to changes in body mass index (BMI) and waist/height ratios at these ages were obtained by logistic regression modelling. There were significant trends of increasing breast cancer risk with increase in BMI from age 20 to 40 (odds ratio [OR] 1.11 [95% confidence interval (CI) 1.05‐1.17] per 2 kg/m² increase in BMI; P < .001), and from age 40 to 60 (OR 1.12 [1.04‐1.20]; P = .003), and with increase in self‐reported adiposity compared to peers at age 11 to BMI compared with peers at age 20 (OR 1.19 [1.09‐1.30]; P < .001). Increase in waist/height ratio from age 20 to 5 years before diagnosis was also highly significantly associated with risk (OR 1.13 [1.08‐1.19]; P < .001). The associations with increases in BMI and waist/height ratio were significant independently of each other and of BMI or waist/height ratio at the start of the period of change analysed, and effects were similar for invasive and in situ tumours separately. Increases in BMI and abdominal obesity are each risk factors for breast cancer in men, independently of obesity per se. These associations might relate to increasing oestrogen levels with weight gain, but this needs investigation.

What's new?

Although obesity is an established risk factor for breast cancer in men, there have been no investigations of whether weight change is an independent risk factor, as it is in women. In an interview case‐control study including 1998 cases and 1597 controls, authors found that increase in body mass index and in abdominal obesity are each significant risk factors for breast cancer in men, independent of obesity per se.

Obesity and Breast Cancer Risk in Men: A National Case-Control Study in England and Wales

Background

Breast cancer is rare in men, and information on its causes is very limited from studies that have generally been small. Adult obesity has been shown as a risk factor, but more detailed anthropometric relations have not been investigated.

Methods

We conducted an interview population-based case-control study of breast cancer in men in England and Wales including 1998 cases incident during 2005-2017 at ages younger than 80 years and 1597 male controls, with questions asked about a range of anthropometric variables at several ages. All tests of statistical significance were 2-sided.

Results

Risk of breast cancer statistically significantly increased with increasing body mass index (BMI) at ages 20 (odds ratio [OR] = 1.07, 95% confidence interval [CI] = 1.02 to 1.12 per 2-unit change in BMI), 40 (OR = 1.11, 95% CI = 1.07 to 1.16), and 60 (OR = 1.14, 95% CI = 1.09 to 1.19) years, but there was also an indication of raised risk for the lowest BMIs. Large waist circumference 5 years before interview was more strongly associated than was BMI with risk, and each showed independent associations. Associations were similar for invasive and in situ tumors separately and stronger for HER2-positive than HER2-negative tumors. Of the tumors, 99% were estrogen receptor positive.

Conclusions

Obesity at all adult ages, particularly recent abdominal obesity, is associated with raised risk of breast cancer in men, probably because of the conversion of testosterone to estrogen by aromatase in adipose tissue. The association is particularly strong for HER2-expressing tumors.

Male Breast Cancer: Clinical, Demographical, and Pathological Features in a Cohort of 41 Patients

Background and objective

Male breast cancer (MBC) is a rare malignancy, and it accounts for less than 1% of all cancers in men. The pathogenesis of MBC remains unclear, with most available data obtained from single-center studies and retrospective series. The aim of this study was to share our experiences of MBC cases and to describe the characteristics of MBC patients.

Materials and methods

We retrospectively reviewed the records of 41 MBC cases and recorded the pathological, clinical, and demographic features of the patients. Data on progression-free survival (PFS) and overall survival (OS) were also recorded.

Results

The mean age of the patients was 64.1 ± 10.0 years. The most common histopathological subtype was invasive ductal carcinoma. Hormone receptor positivity was detected in 39 (95.1%) patients. Human epidermal growth factor receptor 2 (HER2) positivity was present in five (12.2%) patients. Most of the patients had early-stage disease. Surgery was the treatment of choice for most primary tumors. Thirty-nine (95.1%) patients received hormonotherapy, and 21 (51.2%) received systemic chemotherapy. OS was found to be 126.4 months and PFS was 83.2 months. The OS and PFS time in patients with a Nottingham Prognostic Index (NPI) score of <5.4 were longer than those with an NPI score of >5.4.

Conclusion

The hormone receptor status of most of the MBC patients was positive, and their HER2 status was negative. A multimodality approach was associated with longer survival, which has been reported in female patients with breast cancer as well. The NPI score is a useful tool for predicting survival time in MBC patients.

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.

Metastatic Prostate Cancer Synchronous with Male Breast Papillary Ductal Carcinoma in situ: Management Dilemma and Literature Review

Prostate cancer is common in men, but tumour of the male breast is rare. For these two tumours to be presented synchronously in a male patient is even rarer. The focus of this paper is the case of a 72-year-old man diagnosed with papillary ductal carcinoma in situ after he presented with a unilateral breast mass associated with nipple discharge. Imaging staging for his breast tumour and subsequent prostate biopsy found an incidental synchronous asymptomatic prostate adenocarcinoma as well as bone metastases. He denies risk factors for malignancies and refuses genetic testing. The first part of our discussion will highlight the uncommon occurrence of male breast ductal carcinoma in situ and its management controversies. The subsequent part of our discussion will focus on the association between male breast cancer and prostate cancer, and implication of this on the future treatment of these patients. More importantly, our case will illustrate the challenges in managing dual primaries that present concurrently.

Male Triple-Negative Breast Cancer

Male breast cancer is a rarely encountered disease, when compared with female breast cancer, often detected in more advanced stage at the time of diagnosis, and associated with more lymph node metastasis rates, more estrogen receptors positivity, and less human epidermal growth factor receptor-2 expression (HER-2) rates. Surgical management also shows some difference, where the most common operative technique of male breast cancer patients is mastectomy and/or axillary surgery. Triple-negative breast cancer is less frequent than other subtypes and is associated with poorer prognosis. This is because of its association with higher histopathological grade than that in other types of breast cancer. Only fewer treatment options are available compared to hormone-positive, HER-2 positive breast cancer. We are present a case of 71-year-old gentleman with triple-negative breast cancer.

Contribution of the tumor and obese microenvironment to triple negative breast cancer

The growing burden of obesity and incidence of the aggressive triple negative breast cancer (TNBC) is a challenge, especially amongst vulnerable populations with unmet medical needs and higher mortality from breast cancer. While some mechanisms linking obesity and TNBC have been identified, the complex nature of pathogenesis, in both obesity as well as TNBC poses a real challenge in establishing a causative role of obesity in risk of TNBC. In this review article, we discuss pathological mechanisms identified in the tumor microenvironment (TME) as well as the obese microenvironment (OME), such as inflammation, insulin resistance and survival pathways that contribute to the development and progression of TNBC. Insights into the cross-talk between TME and OME, and their contribution to TNBC development and progression, may pave the way for personalized therapies against TNBC progression, relapse and metastasis.

An updated review of epidemiology, risk factors, and management of male breast cancer

Unlike female breast cancer, male breast cancer (MBC) is rare and not very well understood. Prospective data in the management of MBC are lacking and majority of treatment strategies are adopted from the established guidelines for breast cancer in women. The understanding of biology, clinical presentation, genetics, and management of MBC is evolving but there still remains a large knowledge gap due to the rarity of this disease. Older age, high estradiol levels, klinefelter syndrome, radiation exposure, gynecomastia, family history of breast cancer, BRCA2 and BRCA1 mutation are some of the known risk factors for MBC. Routine screening mammography is not recommended for asymptomatic men. Diagnostic mammogram with or without ultrasound should be considered if there is a suspicion for breast mass. Majority of men with early-stage breast cancer undergo mastectomy whereas breast conserving surgery (BCS) with sentinel lymph node biopsy (SLNB) remains an alternative option in selected cases. Since the majority of MBC are hormone receptor positive (HR+), adjuvant hormonal therapy is required. Tamoxifen for a total of 5 to 10 years is the mainstay adjuvant hormonal therapy. The role of neoadjuvant and adjuvant chemotherapy for early-stage breast cancer is uncertain and not commonly used. The role of gene recurrence scores like oncotype Dx and mammaprint is evolving and can be used as an aid for adjuvant chemotherapy. Majority of metastatic MBC are treated with hormonal therapy with either tamoxifen, gonadotropin-releasing hormone agonist (GnRH) with aromatase inhibitors (AI), or fulvestrant. Chemotherapy is reserved for patients with visceral crisis or rapidly growing tumors.

The Tumor Promotional Role of Adipocytes in the Breast Cancer Microenvironment and Macroenvironment

The role of the adipocyte in the tumor microenvironment has received significant attention as a critical mediator of the obesity-cancer relationship. Current estimates indicate that 650 million adults have obesity, and thirteen cancers, including breast cancer, are estimated to be associated with obesity. Even in people with a normal body mass index, adipocytes are key players in breast cancer progression because of the proximity of tumors to mammary adipose tissue. Outside the breast microenvironment, adipocytes influence metabolic and immune function and produce numerous signaling molecules, all of which affect breast cancer development and progression. The current epidemiologic data linking obesity, and importantly adipose tissue, to breast cancer risk and prognosis, focusing on metabolic health, weight gain, and adipose distribution as underlying drivers of obesity-associated breast cancer is presented here. Bioactive factors produced by adipocytes, both normal and cancer associated, such as cytokines, growth factors, and metabolites, and the potential mechanisms through which adipocytes influence different breast cancer subtypes are highlighted.

Family history of breast cancer in men with non-BRCA male breast cancer: implications for cancer risk counseling

PURPOSE

The role of genetic predisposition in male breast cancer (MBC) patients who test negative for a BRCA mutation is unclear. The aim of this study is to define the association between MBC and family history of breast cancer in patients without mutations in BRCA1 or BRCA2.

METHODS

We conducted an unmatched case-control study with men who received commercial testing for germline mutations in cancer susceptibility genes, including 3,647 MBC cases who tested negative for deleterious mutations in BRCA1/BRCA2, and 4,269 men with a personal history of colorectal cancer who tested negative for mutations in DNA mismatch repair genes to serve as controls. Associations between family history of breast cancer and MBC were estimated using unconditional multivariable logistic regression with adjustment for age, race/ethnicity and year of testing.

RESULTS

Breast cancer in a first- or second-degree relative was associated with a four-fold increased odds of MBC (OR 4.7; 95% CI 4.1, 5.3). Associations with MBC were strongest for family history of breast cancer in 2 or more first-degree relatives (FDR) (OR 7.8; 95% CI 5.2, 11.6), for probands and FDR diagnosed at age < 45 years (OR 6.9; 95% CI 3.9, 12.4), and for family history of MBC (OR 17.9; 95% CI 7.6, 42.1). Findings were confirmed in a sensitivity analysis of MBC cases who tested negative on a 25-gene pan-cancer panel.

CONCLUSIONS

MBC patients without mutations in BRCA1/2 have significantly higher odds of a family history of breast cancer, suggesting the existence of unidentified MBC susceptibility alleles.

Male Breast Cancer Risk Assessment and Screening Recommendations in High-Risk Men Who Undergo Genetic Counseling and Multigene Panel Testing

BACKGROUND

Emerging data suggest screening mammography may be effective in detecting breast cancer early in high-risk men. We evaluated current screening recommendations as a risk management strategy in men at elevated risk for breast cancer.

PATIENTS AND METHODS

This institutional review board-approved, Health Insurance Portability and Accountability Act (HIPAA)-compliant study reviewed consecutive men who underwent genetic counseling and multigene panel testing (MGPT) for breast cancer risk assessment at our institution between 2012 and 2018. Patient risk factors, test indications, and MGPT outcomes were recorded, then correlated with screening recommendations by either clinical breast examination or screening mammography. Recommendation consistency among practitioners was evaluated. Patient adherence to screening mammography (defined as undergoing screening mammography as recommended) was assessed. Statistical analysis was performed at the 2-sided 5% significance level.

RESULTS

A total of 414 asymptomatic men underwent both genetic counseling and MGPT (mean age, 47 years; range, 18-91 years) for breast cancer risk assessment. Of this group, 18 (4.3%) of 414 had a personal history of breast cancer, and 159 (38.4%) of 414 had a family history of breast cancer before MGPT. Among 112 men with positive MGPT results, BRCA1/2 mutations were the most common (56.3%, 63/112). Most BRCA mutation carriers (80.9%, 51/63) were recommended clinical breast examination only. Only 5.9% (2/34) BRCA2 and 10.3% (3/29) BRCA1 carriers were recommended screening mammograms (7.9%, 5/63 of all BRCA carriers). Among men with a personal history of breast cancer, only 9 (50%) of 18 were recommended screening mammograms. Overall adherence to screening mammogram in men was 71.4% (10/14), which ultimately yielded two cancers. Breast cancer screening recommendations varied widely among practitioners, with some recommending clinical breast examination only, and others also recommending mammography.

CONCLUSION

Men who are found to be at an elevated risk for breast cancer after undergoing genetic counseling and testing currently receive relatively inconsistent screening recommendations.

Image-based screening for men at high risk for breast cancer: Benefits and drawbacks

Male breast cancer is a rare malignancy. Due to low prevalence and limited data to support male breast cancer screening, there are currently no recommendations for image-based screening in asymptomatic men and few recommendations for men at high risk for breast cancer. However, symptomatically diagnosed cancers in men are typically advanced, suggesting that earlier detection may improve outcomes. In this article we briefly review the risk factors for male breast cancer, and discuss the potential benefits and possible drawbacks of routine image-based screening for men at high risk for breast cancer.

Subtype-Specific Breast Cancer Incidence Rates in Black versus White Men in the United States

Compared with white women, black women have higher incidence rates for triple-negative breast cancer but lower rates for hormone receptor (HR)–positive cancers in the United States. Whether similar racial difference occurs in male breast cancer is unclear. We examined racial differences in incidence rates of breast cancer subtypes defined by HR and human epidermal growth factor receptor 2 (HER2) by sex using nationwide data from 2010 to 2016. Among men, rates were higher in blacks than whites for all subtypes, with the black-to-white incidence rate ratios of 1.41 (95% confidence interval [CI ]= 1.32 to 1.50) for HR+/HER-, 1.65 (95% CI = 1.40 to 1.93) for HR+/HER2+, 2.62 (95% CI = 1.48 to 4.43) for HR-/HER2+, and 2.27 (95% CI = 1.67 to 3.03) for triple-negative subtype. Conversely, among women, rates in blacks were 21% lower for HR+/HER2- and comparable for HR+/HER2+ but 29% and 93% higher for HR-/HER2+ and triple-negative subtypes, respectively. Future studies are needed to identify contributing factors to the dissimilar racial patterns in breast cancer subtype incidence between men and women.

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.

Clinical features of patients with male breast cancer in Shanxi province of China from 2007 to 2016

This study aims to understand the clinical features, treatment, and prognosis of patients with male breast cancer (MBC) in Shanxi province of China from 2007 to 2016. Data for 77 patients with MBC were collected for analysis. Immunohistochemistry, pathological results, and other data such as demographic characteristics (age, marital status, smoking history, drinking history, and family history of cancer) as well as clinical data were investigated by retrieving information from the patients' medical records. A total of 12,404 patients were diagnosed with breast cancer between 2007 and 2016, and 77 were patients with MBC among them. The median diagnosis age of patients with MBC was 62 years (range, 24-84 years). The most common complaint was a painless lump in the breast, accounting for 68.8% of the patients, and the main pathological type in MBC was infiltrating ductal carcinoma (66.2%). In terms of hormone receptors, 80.5% (62/77) of patients with MBC were estrogen receptor positive, 75.3% (58/77) of patients were progesterone receptor positive, and only 6.5% (5/77) of patients were HER2 overexpressing. The multivariant Cox proportional hazards regression analysis showed that M stage is an independent prognostic factor (p=0.018, HR=18.791, 95% CI 1.663 to 212.6). The epidemiological and clinical features of Chinese MBC are similar to that of other countries. As the Chinese public have limited knowledge of MBC, it is necessary to increase awareness among them about it. Further research with a large sample size is required for better understanding of the risks associated with MBC.

Influence of Age on the Clinical Outcome of Breast Cancer for Men and the Development of Second Primary Cancers

BACKGROUND

Low incidence of breast cancer in men (BCM) (< 1% of all breast cancers) has led to a paucity of outcome data. This study evaluated the impact of age on BCM outcomes.

METHODS

For this study, BCM patients treated between 2000 and 2011 were stratified by age (≤ 65 or > 65 years). Kaplan-Meier methods were used to compare overall survival (OS) and breast cancer-specific survival (BCSS). Competing-risk methods analyzed time to second primary cancers (SPCs), with any-cause death treated as a competing risk.

RESULTS

The study identified 152 BCM patients with a median age of 64 years (range 19-96 years). The median body mass index (BMI) was 28 kg/m². Men age 65 years or younger (n = 78, 51%) were more overweight/obese than men older than 65 years (n = 74, 49%) (89% vs 74%, respectively; P = 0.008). Both groups had similar nodal metastases rates (P = 0.4), estrogen receptor positivity (P = 1), and human epidermal growth factor receptor 2 (HER2)neu overexpression (P = 0.6). Men 65 years of age or younger were more likely to receive chemotherapy (P = 0.002). The median follow-up period was 5.8 years (range 0.1-14.4 years). The 5-year OS was 86% (95% confidence interval [CI] 80-93%), whereas the 5-year BCSS was 95% (95% CI 91-99%). The BCM patients 65 years of age and younger had better OS (P = 0.003) but not BCSS (P = 0.8). The 5-year cumulative incidence of SPC was 8.4% (95% CI 3.4-13.4%). The prior SPC rate was higher for men older than 65 years (n = 20, 31%) than for those age 65 years or younger (n = 7, 11%) (P = 0.008). This did not account for differences in life years at risk. No difference was observed in SPC cumulative incidence stratified by age (P = 0.3).

CONCLUSIONS

Men 65 years of age or younger received more chemotherapy and had improved OS, but not BCSS, compared with men older than 65 years. For all BCM, SPC is a risk, and appropriate screening may be warranted.

5-alpha Reductase Inhibitors and risk of male breast cancer: a systematic review and meta-analysis

OBJECTIVE

To assess the relationship between 5α-reductase inhibitors (5ARIs) and the risk of male breast cancer (MBC).

MATERIAL AND METHODS

We systematically searched Medline via PubMed, Embase and the Cochrane Library Central Register up to May 2017 to identify published articles related to 5ARIs and the risk of MBC.

RESULTS

Summary effect estimates were calculated by a random-effect model, and tests for multivariable-unadjusted pooled risk ratios (RR) and heterogeneity, as well as the sensitivity analyses were conducted to assess publication bias. All four studies were conducted in a quality assessment according to the Newcastle Ottawa Scale system. The strength of association between 5ARIs and the prevalence of MBC was evaluated by using summarized unadjusted pooled RR with a 95% confidence interval [CI]. Four studies involving 595.776 participants, mean age range from 60 to 73.2 years old, were included in a meta-analysis, which produced a summary unadjusted RR of the risk of MBC for the treatment of 5ARIs of 1.16 (95% CI 0.85-1.58, P=0.36) and the multivariable-adjusted RR is 1.03, (95% CI 0.75-1.41, p=0.86). There was no heterogeneity among included studies (I2=0%, P=0.49). Estimates of total effects were generally consistent with the sensitivity.

CONCLUSION

We did not observe a positive association between the use of 5ARIs and MBC. The small number of breast cancer cases exposed to 5ARIs and the lack of na association in our study suggest that the development of breast cancer should not influence the prescribing of 5ARIs therapy.

Male Breast Cancer in the Age of Genetic Testing: An Opportunity for Early Detection, Tailored Therapy, and Surveillance

In detection, treatment, and follow-up, male breast cancer has historically lagged behind female breast cancer. On the whole, breast cancer is less common among men than among women, limiting utility of screening, yet the incidence of male breast cancer is rising, and there are men at high risk for breast cancer. While women at high risk for breast cancer are well characterized, with clearly established guidelines for screening, supplemental screening, risk prevention, counseling, and advocacy, men at high risk for breast cancer are poorly identified and represent a blind spot in public health. Today, more standardized genetic counseling and wider availability of genetic testing are allowing identification of high-risk male relatives of women with breast cancer, as well as men with genetic mutations predisposing to breast cancer. This could provide a new opportunity to update our approach to male breast cancer. This article reviews male breast cancer demographics, risk factors, tumor biology, and oncogenetics; recognizes how male breast cancer differs from its female counterpart; highlights its diagnostic challenges; discusses the implications of the widening clinical use of multigene panel testing; outlines current National Comprehensive Cancer Network guidelines (version 1, 2018) for high-risk men; and explores the possible utility of targeted screening and surveillance. Understanding the current state of male breast cancer management and its challenges is important to shape future considerations for care. Shifting the paradigm of male breast cancer detection toward targeted precision medicine may be the answer to improving clinical outcomes of this uncommon disease. ^©RSNA, 2018.

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.

A Case Report of Triple-Positive Micropapillary Carcinoma of the Male Breast

Background

Micropapillary carcinoma (MPC), a morphologically distinct subtype of invasive ductal carcinoma, of the male breast is an exceedingly uncommon disease.

Case Report

Herein, we report a case of triple-positive MPC of the male breast with axillary lymph node involvement and no recurrence for over 2 years. Specifically, a 60-year-old male patient presented with a hard, elastic, and well-defined painless mass in the right breast. The patient underwent unilateral (right) modified radical mastectomy with axillary clearance. Histopathology revealed MPC grade 3 and metastasis in 16/16 lymph nodes. Hormone receptor analysis demonstrated strong positivity (total score 08) for estrogen/progesterone receptors and overexpression (score 3+) of human epidermal growth factor receptor 2. The patient received adjuvant chemotherapy (6 courses of CAF: cyclophosphamide, doxorubicin, and 5-fluorouracil), radiation, and tamoxifen. The patient has remained disease-free for over 2 years.

Conclusion

This study demonstrates that triple-positive MPC of the male breast as a rare malignancy appears to respond promisingly to multimodality treatment.

Advanced breast cancer in a relatively young man with severe obesity and type 2 diabetes mellitus

It is known that male breast cancer is extremely rare and obesity is a strong risk factor of breast cancer in both male and female. In general, the prognosis in breast cancer in males is known to be very poor compared to that in females as it tends to be more advanced stage due to delayed initial diagnosis. Therefore, we should be aware of the possibility that breast cancer could be developed even in relatively young males without any specific risk factors especially when the subjects have severe obesity.

Descriptive characteristics of prostate cancer in patients with a history of primary male breast cancer - a SEER analysis

Background

Current evidence on risk of prostate cancer following a diagnosis of male breast cancer is limited and guidance for screening in this potentially higher-risk population remainsunclear. Our objective was to quantify prostate cancer risk in men diagnosed with breast cancer.

Methods

We identified men diagnosed with first primary breast cancer between 1988 and 2012 using the Surveillance, Epidemiology and End Results Program registry databases. Men were followed for occurrence of a second primary prostate cancer and secondary outcomes of cancer-specific and overall survival. Stratified analyses were performed by age, breast cancer stage, race, and breast cancer hormone receptor status. Excess risk per 10,000 person-years and standardized incidence ratios (SIR) with 95% confidence intervals (95% CI) were calculated. We used multivaraible Cox proportional hazard models to estimate hazard ratios (HR) and 95% CI for characteristics associated with secondary prostate cancer and survival.

Results

From a cohort of 5753 men with breast cancer with median follow up of 4.3 years, we identified 250 cases of second primary prostate cancer. Overall, the incidence of second primary prostate cancer was modestly greater than expected (SIR = 1.12, 95% CI 0.93–1.33), although not statistically significant. Stratified analyses demonstrated associations for men ages 65–74 at the time of breast cancer diagnosis (SIR = 1.34, 95%CI 1.01–1.73), hormone receptor-positive breast cancer (SIR = 1.23, 95%CI 1.11–1.39) or AJCC stage I breast cancer (SIR = 1.36, 95%CI 1.04–1.75) and second primary prostate cancer diagnosis.

Conclusions

The incidence of prostate cancer in men with history of breast cancer is similar to the general population. Men with favorable characteristics of their breast cancer were more likely to develop prostate cancer, possibly due to a lower competing risk of breast cancer mortality.

CHEK2 c.1100delC mutation is associated with an increased risk for male breast cancer in Finnish patient population

Background

Several susceptibility genes have been established for female breast cancer, of which mutations in BRCA1 and especially in BRCA2 are also known risk factors for male breast cancer (MBC). The role of other breast cancer genes in MBC is less well understood.

Methods

In this study, we have genotyped 68 MBC patients for the known breast or ovarian cancer associated mutations in the Finnish population in CHEK2, PALB2, RAD51C, RAD51D, and FANCM genes.

Results

CHEK2 c.1100delC mutation was found in 4 patients (5.9%), which is significantly more frequent than in the control population (OR: 4.47, 95% CI 1.51–13.18, p = 0.019). Four CHEK2 I157T variants were also detected, but the frequency did not significantly differ from population controls (p = 0.781). No RAD51C, RAD51D, PALB2, or FANCM mutations were found.

Conclusions

These data suggest that the CHEK2 c.1100delC mutation is associated with an increased risk for MBC in the Finnish population.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3631-8) contains supplementary material, which is available to authorized users.

Male Breast Cancer Incidence and Mortality Risk in the Japanese Atomic Bomb Survivors - Differences in Excess Relative and Absolute Risk from Female Breast Cancer

BACKGROUND

There are well-known associations of ionizing radiation with female breast cancer, and emerging evidence also for male breast cancer. In the United Kingdom, female breast cancer following occupational radiation exposure is among that set of cancers eligible for state compensation and consideration is currently being given to an extension to include male breast cancer.

OBJECTIVES

We compare radiation-associated excess relative and absolute risks of male and female breast cancers.

METHODS

Breast cancer incidence and mortality data in the Japanese atomic-bomb survivors were analyzed using relative and absolute risk models via Poisson regression.

RESULTS

We observed significant (p ≤ 0.01) dose-related excess risk for male breast cancer incidence and mortality. For incidence and mortality data, there are elevations by factors of approximately 15 and 5, respectively, of relative risk for male compared with female breast cancer incidence, the former borderline significant (p = 0.050). In contrast, for incidence and mortality data, there are elevations by factors of approximately 20 and 10, respectively, of female absolute risk compared with male, both statistically significant (p < 0.001). There are no indications of differences between the sexes in age/time-since-exposure/age-at-exposure modifications to the relative or absolute excess risk. The probability of causation of male breast cancer following radiation exposure exceeds by at least a factor of 5 that of many other malignancies.

CONCLUSIONS

There is evidence of much higher radiation-associated relative risk for male than for female breast cancer, although absolute excess risks for males are much less than for females. However, the small number of male cases and deaths suggests a degree of caution in interpretation of this finding. Citation: Little MP, McElvenny DM. 2017. Male breast cancer incidence and mortality risk in the Japanese atomic bomb survivors - differences in excess relative and absolute risk from female breast cancer. Environ Health Perspect 125:223-229; http://dx.doi.org/10.1289/EHP151.

The Epidemiology of Male Breast Cancer

Male breast cancer is a rare disease, accounting for only 1% of breast cancer diagnoses in the USA. The current literature suggests that genetic factors including BRCA2 mutations, family history, age, androgen/estrogen imbalance, and environmental exposures may predispose to male breast cancer. In this manuscript, we will review known and possible risk factors for male breast cancer, as well as describe the clinical patterns of the disease.

Breast cancer in a male-to-female transsexual patient with a BRCA2 mutation

Breast cancer is rare in male patients. Certain predisposing factors, be they genetic (e.g., BRCA2 gene mutations) or hormonal (imbalance between estrogen and androgen levels), have been implicated in male breast cancer pathophysiology. Male-to-female (MtF) transsexualism is a condition that generally involves cross-sex hormone therapy. Anti-androgens and estrogens are used to mimic the female hormonal environment and induce the cross-sex secondary characteristics. In certain situations, the change in the hormonal milieu can be disadvantageous and favor the development of hormone-dependent pathologies, such as cancer. We report a case of a MtF transgender patient who developed breast cancer after 7 years of cross-sex hormonal therapy. The patient was found to be BRCA2 positive, and suffered recurrent disease. The patient was unaware of being a member of an established BRCA2 mutation-positive kindred. This represents the first case of a BRCA2 mutation predisposing to breast cancer in a MtF transgender patient.

Male Breast Cancer

Male breast cancer (MBC) is a rare disease, accounting for less than 1% of all breast cancer diagnoses worldwide. Although breast carcinomas share certain characteristics in both genders, there are notable differences. Most studies on men with breast cancer are very small. Thus, most data on male breast cancer are derived from studies on females. However, when a number of these small studies are grouped together, we can learn more from them. This review emphasizes the incidence, etiology, clinical features, diagnosis, treatment, pathology, survival, and prognostic factors related to MBC.

Optimal delivery of male breast cancer follow-up care: improving outcomes

Male breast cancer is a rare disease. There are limited data to inform optimal treatment and follow-up strategies in this population. Currently, most follow-up guidelines are drawn from the vast literature on female breast cancer, despite the fact that male breast cancer has unique biological characteristics. In this review, we discuss clinical characteristics of male breast cancer as well as current best practices for long-term care with a focus on surveillance, screening, and treatment-related symptom management in male breast cancer survivors.