Male breast cancer (MBC) is rare, and research on the predictors of MBC has been limited because of inadequate funding in and outside of the United States. One goal of this study was to eradicate the stereotyping of breast cancer as a female disease. The emergence of medical technology and education to benefit the public will help to ensure greater health awareness at the individual, community, and global levels. The purpose of this study was to understand the influence of the predictors of age; race (Black, White, and Other); and grade of cancer (I, II, or III) on the outcome of mastectomy in MBC. The study was guided by the social determinants of health model. A quantitative approach was used to analyze archival data from 2011 to 2013 in the Surveillance Epidemiology and End Results (SEER) database using SPSS v.23. Data from 427 MBC patients ages 18 years and older from the United States comprised the sample. The SEER data were analyzed using logistic regression analysis. Results showed that of the 427 cases of MBC that were analyzed, 55 had a diagnosis of Grade I, 190 had a diagnosis of Grade II, and 182 had a diagnosis of Grade III. For 3 years, 116 men had undergone mastectomy. Grade I cancer, Grade II cancer, and Grade III cancer were statistically insignificant predictors of mastectomy; however, age, race was a statistically significant predictor of mastectomy among White men with MBC. The results will contribute to social change initiatives by educating the public about the predictors of mastectomy in MBC patients. The results also will increase the current knowledge base by informing the public, clinical professionals, and patients about the relationship of the predictors of age; race; and grade of cancer (I, II, or III) on the outcome of mastectomy in MBC.

The aim of this thesis was to investigate different aspects of male breast cancer (MBC), and to compare these with findings in female breast cancer (FBC). In paper I, a population–based study was performed to investigate possible differences in treatment and outcome between MBC and FBC patients. MBC and FBC presented with a similar distribution of stage. Although no differences in primary treatment strategy were demonstrated, MBC patients had significantly poorer overall and relative survival, indicating a more aggressive disease. Paper II aimed to assess the value of clinicopathological factors and molecular subtypes in MBC. One hundred and ninety-seven MBC tumors were characterized using immunohistochemistry (IHC) and the findings were correlated to outcome. Lymph node positivity, larger tumor size and ER-negativity were independent risk factors for breast cancer death. Tumor grade, HER2, Ki 67 or IHC classification into molecular subtypes did not demonstrate any prognostic information. In paper III, the same patient material as in paper II was used for evaluation of proliferation markers. High levels of cyclin A and cyclin B expression and an elevated mitotic count were predictive of breast cancer death. Ki-67 was re-evaluated using different cut-offs, but no prognostic value could be demonstrated. Contrarily, overexpression of cyclin D1 was associated with a lower risk of breast cancer death. In papers IV-V, the molecular background of MBC tumors was investigated.  Global GEX analyses were performed and two novel subgroups of MBC tumors were identified; luminal M1 and luminal M2. When comparing the degree of similarity with the “intrinsic” subtypes in FBC tumors, more than half of the MBC tumors remained unclassified.  Comparative genomic hybridization was used to investigate DNA aberrations. Two MBC subgroups were identified, of which one did not resemble any of the female subgroups. In both studies on the molecular level, a majority of patients were classified into the subgroup with a more aggressive tumor behavior. In conclusion, MBC seems to be a unique tumor entity. The established molecular subtypes in FBC are not applicable in MBC. Other prognostic profiles, specific for MBC, need to be identified.

In spite of the fact that prostate cancer is the most common male cancer in both Sweden and many other countries in the developed world, little is known of risk factors and predisposing conditions. The only well recognized risk factors are age, race and familial aggregation. More knowledge about risk factors could lead to better preventive measures together with better treatments. One way to evaluate this is to study second primary cancers; the connection between two different cancers can give valuable insight in etiology or clues to shared risk factors. This thesis aims at evaluating risk factors for prostate cancer. We constructed a cohort of 135,713 men diagnosed with prostate cancer and reported to the Swedish Cancer Registry 1958-1996. The cohort was followed for second primary cancers and a doubled risk of male breast cancer was found. We also noted increased risks for small intestine cancers and melanoma. As a follow-up on the increased risk of male breast cancer, we performed a nested case – control study. Included cases were men with first prostate and then breast cancer (n = 41) matched to men with only prostate cancer (n =81). For these men, we collected medical records and extracted data regarding treatment. Furthermore, all men diagnosed with both prostate and breast cancer irrespective which came first (n = 83) were used as probands. To both these sets of cases with breast and prostate cancer, we identified first degree relatives and grandchildren from parish offices throughout Sweden. Linking to the Cancer Registry retrieved all cancer diagnoses amongst relatives. Results from this study show a relation between estrogen treatment of prostate cancer and the risk of developing breast cancer. We also found that a small part of the cases with both cancers appeared in families with inheritance patterns possibly attributed to BRCA2. As estrogen treatment seemed involved in increased risk of breast cancer after prostate cancer, we wanted to investigate the newly discovered Estrogen receptor β and the relation to prostate cancer risk. Previous reports have shown that ERβ acts as a negative regulator of proliferation. ERβ expression occurs mainly in prostatic epithelial cells and the expression gradually diminishes when cancer develops and aggravates. We used a single nucleotide polymorphism (SNP) association study approach to evaluate genetic variation in ERβ as a risk factor for prostate cancer. One SNP, located in the promoter region associated with a small increased risk of prostate cancer whereas variation in the rest of the gene did not. In the last paper, we investigated trans-urethral resection (TURP) of the prostate due to benign prostate hyperplasia (BPH) as a risk factor for later development of prostate cancer. Evidence has gathered that both BPH and prostate cancer are associated to inflammation. By comparing incidence and mortality in a cohort of 7,901 men with the general population there appeared to be an increased risk of prostate cancer but decreased mortality. Analyzing this increased risk further, we conducted a nested case - control study with men extracted from the cohort. Cases had a TURP and later developed prostate cancer and controls just had a TURP. We then evaluated the specimens from TURP regarding extent of inflammation, degree of androgen receptor down regulation and expression of p53, all factors previous associated with prostate cancer. None of these parameters differed between cases and controls and they can therefore not explain the increased risk. Decreased mortality but increased risk might be explained by surveillance bias, which means more medical attention to these patients, resulting in diagnosing clinically non-significant cancers. In summary, our results show a doubled risk of male breast cancer following prostate cancer. A risk that can be attributed to the use of estrogen to treat prostate cancer or to some extent a possible mutation in BRCA2. We also propose that a SNP change in the ERβ promoter confer a small increased risk of prostate cancer. A small risk elevation of prostate cancer following TURP most probable could depend on surveillance bias.

Bakgrund: Bröstcancer hos män är en ovanlig, ouppmärksammad sjukdom. Mindre än en procent av alla som får bröstcancer är män. Detta gör att männen som drabbas av denna sjukdom inte bara går igenom de motgångar som en cancersjukdom innebär utan även vad det kan innebära att drabbas av en sjukdom som vanligen drabbar kvinnor. Syfte: Att beskriva mäns upplevelse av att leva med bröstcancer. Metod: En litteraturöversikt då nio stycken vetenskapliga originalstudier granskades. Dessa hade kvalitativ, kvantitativ eller mixad metod och hämtades från Cinahl och referenslistor från andra vetenskapliga artiklar. Studierna analyserades genom en indelning av data i olika huvudteman och underteman. Resultat: I resultatet framkom det tre huvudteman i den manliga bröstcancerupplevelsen. Dessa var: mötet med vården, livet under behandlingen och livet efter diagnosen. Ett antal underteman framkom även för att enklare strukturera resultatet. I mötet med vårdpersonal upplevde männen att det förekom svårigheter vid både givande av diagnos och utformning av stöd. Informationen som gavs ansågs som otillräcklig och opassande. Sjukdomen fick många män att reflektera över synen på sin maskulinitet. I livet efter diagnosen framkom de psykiska påverkningarna för männen vilka kunde innebära stress och ångest. Vissa män såg dock erfarenheten av sjukdomen som någonting positivt då det innebar omarbetade värderingar och en ny syn på livet. Diskussion: Resultatet diskuteras med utgångspunkt i ett livsvärldsperspektiv med den levda kroppen som ett centralt begrepp. Det diskuteras och jämförs skillnader och likheter i artiklarna och även hur författarna förstår och tolkar sitt resultat. / Background: Male breast cancer is a rare and unnoticed disease. Less than one per cent of all breast cancer cases are male. This contributes to the male breast cancer patient not only encountering adversities related to a cancer diagnosis but also all that it entails to have a disease that normally affects women. Aim: To describe the male breast cancer experience. Method: This was a literary review where nine original studies all relating to the aim of the review were analysed. These were retrieved from Cinahl and from reference lists from other scientific articles. The articles had either a qualitative, quantitative or mixed method approach. The studies were analysed through a division of the data into different themes. Results: The results derived three major themes in the male breast cancer experience. These were: meeting with healthcare professionals, life during the treatment and life after the diagnosis. There were also a number of subthemes that where composed to give structure to the findings. When dealing with healthcare professionals the men experienced difficulties in regards to receiving the diagnosis and in what way support was given. The information that was given was inadequate and inappropriate. For some men the disease brought with it reflections of how they viewed their own masculinity. Life after the diagnosis was for some men characterized by stress and anxiety but was for others seen as a positive experienced that brought with it changed values and a new outlook on life.  Discussion: The result is here discussed with a life-world approach with the lived body as a major concept. Differences and similarities in the articles are discussed and compared and there is also an interpretation as to how the authors comprehend their result.