Breast cancer is the most common cancer among women in the United States. Some women are at higher risk for breast cancer than others due to their personal or family medical history or due to certain changes in their genes. Breast cancer remains the second leading cause of cancer death among women overall and the leading cause of cancer death among Hispanic women. According to CDC, each year in the United States, there are about 237,000 cases of breast cancer diagnosed in women and about 41,000 women in the United States die each year from breast cancer. Two independently published, peer-reviewed journal articles, both asserting similar hypotheses, but with different study designs, were examined in analyses and interpretations of health data, to describe the risk factors of leading to breast cancer among postmenopausal women.
The first article referenced, Risk Factors for Breast Cancer in Postmenopausal Women in Brazil, by authors Borghesan, Agnolo, Gravena, Demitto, Lopes, Carvalho, and Pelloso, embarks on a research to identify risk factors for breast cancer in postmenopausal women in Brazil. Determining the risk factors in this study was crucial because it helps to identify population groups who are more prone to the disease and helps address the cases to reduce morbidity and mortality.
In Latin America, it is known that breast cancer is the most common malignant neoplastic disease in women and mortality rates for this disease are higher than in developing countries. Researchers claim that in Brazil, projections for the year 2014 and 2015 that there will be 57.210 new breast cancer cases, with a risk of occurrence of 56.09 cases per 100,000 women. The increase prevalence of breast cancer cases has been tied to both reproductive and hormonal factors, including age at menarche, age at first birth, number of pregnancies, and use of oral contraceptives. According to the Brazilian Ministry of Health, the primary risk factors for breast cancer are known to be linked to age, genetics, and endocrine factors. In consideration to this, the aim of the research study was to analyze the risk factors for postmenopausal breast cancer in women (Pelloso, 2016).
A case-control study was conducted that included 600 women who were treated at a cancer centered reference hospital in Brazil from October 2013 to October 2014. Women with a histologically confirmed diagnosis of breast cancer within six months from the time of the interview screening were evaluated as possible causes. For each case in the field, five control subjects were included, resulting in a total of 500 controlled subjects. As part of the control group, women who had visited the hospital for routine breast examinations were randomly chosen. Apart from the inclusions of the study, exclusions included women who suffered breast cancer recurrence, had any history of cancer, or were diagnosed more than six months prior to the date of the interview.
STATISICAL ANALYSES RESULTS
A descriptive (mean and standard deviation) and a crude analysis using the crudes odd ratio were performed on the data that was collected. The chi-square test and Fisher’s exact test were also implemented to see whether there was an association between the variables, and the cases of breast cancer. Variables that had a descriptive level of significance less than 0.20 for multivariate analysis and logistic regression were looked into the relationship between independent variables and the outcome variable. The analyses were performed using statistical 7.1 and a 5% level of significance was implemented. Risk factors for breast cancer that were considered included an age ? 40 years, postmenopausal status, a body mass index (BMI) ? 30 kg/m2, and reduced physical activity. Based on results, the postmenopausal status and an obese BMI were associated with cases of breast cancer. Hence, women who were postmenopausal or obese were 3.80 or 1.80 times more likely to develop breast cancer, and physically inactive women were 1.72 times more likely to develop breast cancer (Pelloso, 2016).
A conclusion was made that postmenopausal status and obesity were related with the occurrence of breast cancer in the population of Brazilian women. Being over 40 years of age was also a statistically significant factor for postmenopausal women. By researchers knowing the risk factors that are related to breast cancer among women, it can aide health care professionals to develop health policies and preventive interventions by focusing on the risk factors that were found in this population of postmenopausal women. Preventive interventions will help reduce morbidity and mortality rates of breast malignant neoplastic disease. These conclusions are agreeable because recent studies suggest that maintaining a healthy diet, an adequate level of physical activity, and a healthy weight, are ways of preventing cancer.
The authors of article one were transparent in explaining several limitations. For example, most patients who were on the study, had less than eight years of formal education, which may have been biased. Not only that, but relying on individuals to remember past personal information introduced the possibility that individuals who are affected by a disease will misremember information. In addition, the Body Max Index (BMI) was classified for obesity. This indicator had limitations such as not distinguishing between lean mass and fat mass, when it comes to describing the distribution of fat in the body.
The article, Cohort Study of Risk Factors for Breast Cancer in Post Menopausal Women, was chosen as comparison piece. The research that is explained in this article was supported in part by the Huntsman Cancer Foundation and the Beamont Foundation. This study was initiated with a similar intellect and concern described in the first article; risk factors of breast cancer among postmenopausal women. However, these authors create a point that knowing that breast cancer risk factors have often been studied, the present study has the advantage of considering many risk factors associated with this type of disease.
Since the current study has the advantage of looking at many risk factors, this allows researchers to find new risk factors, assess the relative importance of risk factors, and assess which factors are secondary. The purpose of this study was to assess more than 800 potential risk factors to identify new predictors of breast cancer and compare the independence and relative importance of risk factors that are proven.
In assessing the study objective of this research, a cohort study was implemented for this particular study. The data for the study was collected by the Women’s Health Initiative (WHI), which was used for evaluating risk factors. The Women’s Health Initiative study design was a long-term national health study that focused on strategies for preventing heart disease, breast and colorectal cancer in postmenopausal women. As part of the recruitment for the study, participants included 93,675 from the observational study, 16,608 from the randomized controlled trial of estrogen plus progesterone (E+P), 10,739 from the randomized controlled trial of estrogen only (estrogen-alone), and 40,785 additional women who were in the diet study and not in a randomized controlled trial of hormone therapy. To reduce the inclusion of participants with a history of breast cancer, those who had a history of breast cancer, a breast removed, or current antineoplastic therapy were excluded for the present study. As a result, a total of 147,202 women were studied (Hartz ; He, 2013).
STATISTICAL ANALYSES RESULTS
As part of the cohort research study, statistical analyses were performed. In this case, the Cox proportional hazard regression model was used to test the association between more than 800 baseline risk factors and incidence of breast cancer. Based on the test that was performed, baseline factors that were independently associated with subsequent breast cancer at the p;0.001 level were breast aspiration, family history, age, weight, history of breast biopsies, estrogen and progestin use, greater age at menopause, etc. On the contrary, risk factors previously reported that were not independently associated with breast cancer in the present study included socioeconomic status, months of breastfeeding, age at first birth, adiposity measures, adult weight gain, timing of initiation of hormone therapy variables. In addition, family history was not found to change the risk associated with other that were tested (Hartz ; He, 2013).
This particular cohort study discovered many factors linked with breast cancer and 20 independently factors associated at the p;0.001 statistical significance level. The large sample size used in the study allowed the detection of weak associations and allowed to estimate the strength of association between the risk factors and breast cancer. Since many factors were examined, it can be concluded that it was possible to display that some factors mediated the risk associated with others.
From this study, there were some limitations that were taken into consideration. For instance, there were some risk factors that were found in previous literature that were weaker in this study and some were not statistically significant. Researchers in the study believe that it is possible that there was a weak association with breast cancer for some risk factors because the variable (e.g., age at menarche) was inaccurately reported by participants. Adding to this, there was no evidence discovered that stressful life events were risk factors, which agrees with some publications.
COMPARISON OF BOTH STUDIES
Even though, both articles focused on the same hypothesis of evaluating the risk factors of breast cancer in postmenopausal women, the conclusions from the studies came out to be different. Since the conclusions of both studies differ from one another, the clinical trial studies that were performed may have contributed to the discrepancy. While article one was a case-control study and article two was cohort study, the risk factors that were identified in the case-control study in article one were more precise, supported by reported evidence of cases of breast cancer in postmenopausal women that were already discovered within a specific type of population. Since the case-control study in article one had identified that obesity and postmenopausal status were the risk factors found to be associated with breast cancer in the concerned population of women, the cohort study in article two, used current data from the WHI to evaluate new potential risk factors that could be linked to breast cancer.
Hartz, A.J., ; He, T. (2013). Cohort Study of Risk Factors for Breast Cancer in Post
Menopausal Women. Retrieved March 27, 2017, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3654090/
Pelloso Borghesan, D., Dell ?Agnolo, C., Franca Gravena, A., Demitto, M., Romeiro Lopes,T.,
Carvalho, M. and Marisa Pelloso, S. (2016). Risk Factors for Breast Cancer inPostmenopausal Women in Brazil.online Asian Pacific Journal of Cancer Prevention
Available at: http//journal.waocp.org/?sid=Entrez:PubMed;id=pmid:27510013;key=
2016.17.7.3587 Accessed 14 Mar. 2018.