Incidence of breast cancer subtypes in immigrant and non-immigrant women in Norway

Gendered interpretations of the causes of breast cancer: a structured review of migrant studies

BACKGROUND

Breast cancer is the most prevalent cancer in women worldwide. Despite it having an etiology that has fixed, genetic as well as modifiable, environmental risk factors, the narrative around breast cancer prevention emphasizes gendered interpretations of the etiology, such as "reproductive factors cause breast cancer" and women should change their behaviors to reduce their risk. Since migrant studies can distinguish environmental from genetic risk factors, we conducted a structured review of migrant studies and assessed prominent cancer website resources to determine evidence of gender bias between breast and prostate cancer.

METHODS

We searched ten online databases for articles with migration as the exposure and breast cancer mortality and/or incidence as the outcome. We also searched using prostate cancer as the outcome to generate a comparison group. We developed rubrics to categorize the studies by study design (single, double, and time dimensional), convergence (a change in incidence or mortality for the migrant population), and concordance (consistency between results and author-attributed etiology). We used chi-square tests to test for differences by cancer type. We web-scraped four notable cancer websites to extract website layouts, risk factor information, and language describing breast cancer etiology and compared it to the content used for prostate cancer.

FINDINGS

Of all 140 studies and 220 comparisons, breast (n = 131) outnumbered prostate cancer studies (n = 89; p-value = 0·005). For both cancers, studies that compared all three populations (the non-migrant, origin, and destination population outcomes) or measured length of stay demonstrated that cancer rates converged with migration. Most authors attributed breast cancer etiology to genetic and environmental factors. Yet, the migrant study results were inconsistent with public health messaging; all four websites framed breast cancer as more modifiable than prostate cancer.

CONCLUSION

Research efforts and public health messaging for breast cancer should consider gendered barriers to changing individual-level risk factors and develop more prevention strategies at the health systems level.

Immunohistochemical Marker Patterns in Female Breast Cancer

BACKGROUND: Breast cancer (BC) represents the most common cancer in women worldwide and in Bulgaria. Its great medico-social importance determines the intensive complex research devoted to BC prevention, early diagnosis and management. AIM: The objective of the present investigation is to reveal some essential peculiarities of four main immunohistochemical markers used in the diagnosis of molecular subtypes of female BC. MATERIALS AND METHODS: During the period between December 1, 2017 and November 30, 2020, we examined a total of 128 randomly selected female BC patients operated on in Marko Markov Specialized Hospital for Active Treatment of Oncological Diseases of Varna, Bulgaria. We analyze BC molecular types and four immunohistochemical markers in BC patients. The expression of estrogen (ER) and progesterone (PR) receptors is assessed in mammary gland biopsies and surgical specimens by using the indirect immunoperoxidase method with EnVision™ FLEX MiniKit, that of HER2 with HercepTest™ and that of Ki-67 proliferation index with Leica Aperio Scan Scope AT2 device. The positivity and negativity of these receptors in single molecular subtypes is evaluated. RESULTS: The luminal B HER2-positive and the luminal B HER2-negative subtypes are most common - in 36.72% and 35.16% of the cases, respectively. TNBC subtype is established in 11.72%) the luminal A - in 8.59% and the non-luminal HER2-positive subtype - in 7.81% of the cases. The positive expression is statistically significantly more common in ER (t=8.972; p<0.0001) and PR (t=2.828; p<0.01), while the negative expression insignificantly prevails in HER2. CONCLUSION: Our immunohistochemical results in female BC patients prove the role of single receptor expression for the proper and timely decision making about the necessity and benefit of additional chemotherapy in selected surgically treated cases.