Clinical and pathological correlations in male breast cancer: intratumoral aromatase expression via tissue microarray

A systematic literature review of the management, oncological outcomes and psychosocial implications of male breast cancer

BACKGROUND

Although male breast cancer (MBC) is a rare disease, accounting for <1% of all breast cancers, it has significant oncological, survival and psychosocial implications for patients. The aim of this study is to assess the latest literature in the diagnosis, management, oncological outcomes, and psychosocial impact of MBC.

METHODS

A systematic literature review was conducted using the PRISMA guidelines (Moher et al., 2009) [1] to explore the management of MBC, with particular focus on investigative imaging, surgical management, oncological outcomes, survival, genetic screening and psychosocial effects. Electronic databases were searched for randomised control trials, cohort studies and case series involving more than 10 patients. Imaging and surgical techniques, local and distant disease recurrence, survival, genetic screening and psychosocial implications in the setting of MBC were assessed.

RESULTS

The search criteria identified 199 articles, of which 59 met the inclusion criteria. This included 39,529 patients, with a mean age of 64.5 years (55-71), and a mean follow-up of 66.3 months (26.2-115). Mastectomy remains the most frequently used surgical technique, with an average of 89.6%. Loco-regional and distant recurrence rate was 10.1% and 21.4% respectively. Disease-free survival (DFS) at 5 and 10 years was 66.8% and 54.5% respectively. Disease-specific survival (DSS) at 5 and 10 years was 87.1% and 67.1% respectively. Overall survival (OS) at 5 and 10 years was 72.7% and 50.7% respectively. Genetic screening was conducted in 38.6% of patients of which 4.8% and 15.8% were found to be BRCA1 and BRCA2 carriers respectively. Psychosocial studies were conducted mainly using questionnaire and interview-based methodology focusing primarily on awareness of breast cancer in men, support available and impact on gender identity.

CONCLUSIONS

This review demonstrates that men present with later stage disease with subsequent impact on survival outcomes. There remains a paucity of high-level evidence and prospective studies are required. There is a need for increasing awareness amongst the public and health care professionals in order to improve outcomes and reduce stigma associated with MBC.

HMG-CoAR expression in male breast cancer: relationship with hormone receptors, Hippo transducers and survival outcomes

Male breast cancer (MBC) is a rare hormone-driven disease often associated with obesity. HMG-CoAR is the central enzyme of the mevalonate pathway, a molecular route deputed to produce cholesterol and steroid-based hormones. HMG-CoAR regulates the oncogenic Hippo transducers TAZ/YAP whose expression was previously associated with shorter survival in MBC. 225 MBC samples were immunostained for HMG-CoAR and 124 were considered eligible for exploring its relationship with hormone receptors (ER, PgR, AR), Hippo transducers and survival outcomes. HMG-CoAR was positively associated with the expression of hormone receptors (ER, PgR, AR) and Hippo transducers. Overall survival was longer in patients with HMG-CoAR-positive tumors compared with their negative counterparts (p = 0.031). Five- and 10-year survival outcomes were better in patients whose tumors expressed HMG-CoAR (p = 0.044 and p = 0.043). Uni- and multivariate analyses for 10-year survival suggested that HMG-CoAR expression is a protective factor (HR 0.50, 95% CI: 0.25–0.99, p = 0.048 and HR 0.53, 95% CI: 0.26–1.07, p = 0.078). Results were confirmed in a sensitivity analysis by excluding uncommon histotypes (multivariate Cox: HR 0.45, 95% CI: 0.21–0.97, p = 0.043). A positive relationship emerged between HMG-CoAR, hormone receptors and TAZ/YAP, suggesting a connection between the mevalonate pathway, the hormonal milieu and Hippo in MBC. Moreover, HMG-CoAR expression may be a favorable prognostic indicator.

Male breast cancer is not congruent with the female disease

It has become customary to extrapolate from the results of treatment trials for female breastcancer and apply them to males with the disease. In the absence of results from national and international randomised trials for male breast cancer (MBC) this appears superficially to be an appropriate response. Closer examination of available data reveals that aspects of the aetiology and treatment of MBC do not fit the simplistic model that men usually have endocrine sensitive tumours which behave like those in postmenopausal women. Most females and males with breast cancer have none of the recognised risk factors, indicating the gaps in our knowledge of the epidemiology of this disease. Several studies have compared epidemiological risk factors for MBC and female breast cancer (FBC) but many have been blighted by small numbers. In comparison with FBC there is a larger proportion of BRCA2 tumours, (occurring in 10% of MBC), and underrepresentation of BRCA1 tumours (found in only 1%), suggesting significant differences in the genetic aetiology of MBC and FBC. Genome-wide association studies in FBC reported single nucleotide polymorphisms (SNPs) in 12 novel independent loci were consistently associated with disease but for MBC 2 SNPs had a significantly increased risk. Molecular profiles of matched cancers in males and females showed a gender-associated modulation of major processes including energy metabolism, regulation of translation, matrix remodelling and immune recruitment. Immunohistochemistry for kinase inhibitor proteins (KIPs) p27Kip1 and p21Waf1 indicate a significant difference in the immunostaining of tumours from male patients compared with females. MBC is almost always estrogen receptor positive (ER+ve) and so systemic treatment is usually endocrine. With evidence in FBC that aromatase inhibitors are more effective than tamoxifen in the postmenopausal it was seemingly logical that the same would be true for MBC. Results however suggest less efficacy with AIs and an increase in risk of mortality compared to tamoxifen. The overall survival in male breast cancer was significantly better after adjuvant treatment with tamoxifen compared to an aromatase inhibitor. These important biological differences point the way to the development of new therapies for MBC based on differences rather than similarities with FBC.

Aromatase inhibitors for metastatic male breast cancer: molecular, endocrine, and clinical considerations

Male breast cancer is a rare condition. Aromatase inhibitors are widely used for treating metastatic male breast cancer patients. In this setting, their use is not substantiated by prospective clinical trials, but is rather driven by similarities supposedly existing with breast cancer in postmenopausal women. This oversimplified approach was questioned by studies addressing the molecular and endocrine roots of the disease. In this manuscript, we discuss relevant aspects of the current use of aromatase inhibitors in metastatic male breast cancer in light of the most updated evidence on the molecular landscape of the disease and the specific changes in the hormonal background occurring with aging. We further point to strategies for blocking multiple hormonal pathway nodes with the goal of improving their therapeutic potential. We searched PubMed from its inception until March 2014 for relevant literature on the use of aromatase inhibitors in metastatic male breast cancer. Selected terms were combined and used both as medical headings and text words. The reference list of the suitable manuscripts was inspected for further publications. Aromatase inhibitors represent the mainstay of treatment in the metastatic setting. Yet, efforts aimed at sharpening the therapeutic potential of aromatase inhibitors still pose a challenge due to the paucity of data. The choice of dual hormonal (or sequential) therapy combining aromatase inhibitors with a GnRH analogue may represent a valid alterative, particularly if informed by cancer- and patient-related features including molecular, endocrine, and clinic characteristics.

An update on male breast cancer and future directions for research and treatment

Male breast cancer is a rare disease for which treatment has been based on the evidence available from female breast cancer. The new genomic tools can better characterize the biology of breast cancer. It is hoping that these will help to clarify possible differences of breast cancer behaviour in male patients, which will have a major impact on treatment strategies and on the conduct of clinical trials in this setting. In this review we will summarize available information on epidemiology, risk factors for breast cancer in men, the new insights of the biology of this disease, current recommendations for treatment and insights for future research.

Male breast cancer: risk factors, biology, diagnosis, treatment, and survivorship

BACKGROUND

The causes, optimal treatments, and medical/psychosocial sequelae of breast cancer in men are poorly understood.

DESIGN

A systematic review of the English language literature was conducted to identify studies relevant to male breast cancer between 1987 and 2012 and including at least 20 patients. Searches were carried out on PubMed using the title terms 'male breast cancer' or 'male breast carcinoma'.

RESULTS

Relevant published data regarding risk factors, biological characteristics, presentation and prognosis, appropriate evaluation and treatment, and survivorship issues in male breast cancer patients are presented. BRCA2 mutations, age, conditions that alter the estrogen/androgen ratio, and radiation are proven risk factors. Disease biology is distinct in men, but diagnostic approaches and treatments for men are generally extrapolated from those in women due to inadequate research in men. Survivorship issues in men may include sexual and hormonal side-effects of endocrine therapies as well as unique psychosocial impacts of the disease.

CONCLUSION

Further research is needed to address gaps in knowledge pertaining to care of male breast cancer patients and survivors.

Male breast carcinoma: increased awareness needed

Male breast carcinoma is a rare condition. Few male breast cancer-specific epidemiological or clinical trial data are available - our understanding of male breast cancer thus comes from studies of female breast cancer, painting an inaccurate picture when it comes to determining contributing factors. Clinicians report an increase in diagnoses of male breast cancer but this has not been formally reported. We therefore undertook a review of data obtained from four western nations: England, Scotland, Canada and Australia. When adjusted for age, this review clearly showed an increase in the incidence of male breast cancer over a 15-year period. Reasons for the increased incidence are discussed in the context of suggested risk factors such as BRCA2 and lifestyle changes over the past few decades. The clinical management of male breast carcinoma is considered, in particular the potential role of aromatase inhibitors and fulvestrant and targeting pathways involving prolactin and androgen receptor.

Positive progesterone receptors and cell proliferation index: an independent association with breast cancer in males

BACKGROUND AND AIM

Breast cancer in males is an uncommon tumor whose management is extrapolated from that used in female breast cancer. This study compared the histopathological and immunohistochemical features of symptomatic breast cancers in males and females.

PATIENTS AND METHODS

A comparison was made between variables of breast cancers from 58 males and 155 females. A descriptive study, a bivariate analysis, and a multivariate analysis using logistic regression were performed.

RESULTS

No differences were found in staging. Significant differences were seen in age (p<0.0005), proportion of papillary carcinoma (p=0.038) and proportion of tumors with an associated intraductal component (p=0.002). There was a greater proportion of males expressing estrogen (p=0.038) and progesterone (p<0.0005) receptors in their tumors, with a significantly higher proliferation index (p<0.0005).

CONCLUSIONS

Breast cancer in males should be considered a condition biologically different from female breast cancer as a result of factors related to the different hormonal influences, reflected mainly in immunohistochemical differences.

Pharmacologic treatment of male breast cancer

Male breast cancer is an uncommon condition. It often occurs in settings in which there is an imbalance between androgens and oestrogens. Genetics plays an important role, as many cases are associated with mutations in BRCA2 or other genes. Male breast cancer occurs at an older age than female breast cancer and is frequently diagnosed at a later stage. Tumors are predominantly oestrogen and progesterone positive. Prognosis is approximately equivalent to that of breast cancer in females when matched for age, stage and hormonal receptors. The recommended treatment for male breast cancer is similar to that for breast cancer in postmenopausal females. However, the presence of androgens in males has a strong effect on the hormonal milieu and the ability of male patients to respond to hormonal agents. When pharmacologic treatment is required, tamoxifen is effective for first-line therapy. Other hormonal approaches such as orchiectomy, aromatase inhibitors and androgen ablation may be useful in later lines of therapy.

Male breast cancer: a review

Male breast cancer (MBC) is rare, with the peak age of onset at 71 years. BRCA2 mutations are more frequent than BRCA1 with 20% of cases giving a family history. Risk factors for MBC are poorly understood and include working in high-ambient temperatures and exhaust fume exposure. MBC is associated with hyperoestrogenic states found in liver disease, Klinefelter's syndrome, gonadal dysfunction or obesity. Most information on treatment of MBC is derived from large randomized trials carried out in female patients. The small numbers of MBC seen in any unit annually has precluded significant trials being carried out.Diagnosis and treatment of MBC is similar to that of female patients, but men tend to be treated with mastectomy rather than breast-conserving surgery. The mainstay of adjuvant therapy or palliative treatment for advanced disease is endocrine, mostly tamoxifen. Prognosis of male patients is equal to that of stage-matched women, but men tend to fare worse because of delay in presentation, leading to a large proportion of patients presenting with stage III or IV disease. Increased input is needed for psychological support for male breast cancer patients. Specific therapeutic questions about MBC need international trials to obtain meaningful answers.