Healthcare Controversies in Epidemiology

Running head: HEALTHCARE
Controversies in Epidemiology
Name of the Student
Name of the University
Author Note

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Answer 1
Contemporary exposure-outcome association- The topic of interest is breast cancer that
refers to cancer development in the breast tissue, which is commonly characterised by presence
of a lump in the breast, in addition to swelling of skin, scaly or red patches on the skin, a change
in the shape of the breast, and release of fluid from the nipples (Kyu et al., 2016). The outcome
in this particular literature is disease specific mortality. Disease specific mortality is defined as
the death rate from a particular disease, for a certain population. The numerator refers to the total
number of deaths that can be attributed to the specific disease. In contrast, the denominator refers
to the total size of the population at a particular time period. The outcome is generally expressed
in relation to 100,000 individuals. An estimated 19,535 cases of breast cancer had been
diagnosed Australia in the year 2019, with as many as 19,371 females being diagnosed with the
disease (Cancer Australia, 2020). This accounted for 14% of all the cases of cancer that had been
diagnosed in the same year. Government reports suggested that approximately 3,090 deaths
occurred due to breast cancer in 2019 with 3,058 death among females, in comparison to 32 that
amongst their male counterparts (Cancer Australia, 2020).
While breast cancer contributed to 6.2% of all cancer related deaths in the same year, the
chances of survival of the diagnosed patients for a minimum of 5 years was found to be 91%. In
addition, in the year 2016, breast cancer was identified to be the fourth major reason for cancer
associated deaths in the nation, besides being the second most reason for death due to cancer
amongst women. Though there were approximately 3,004 deaths due to breast cancer in 2016,
Australia has been identified to have one of the best survival rates for breast cancer all across the
globe (Breastcancer.org.au, 2020). The rate of survival for females having been diagnosed with
breast cancer is approximately 90.1%, which can be directly attributed to early cancer detection

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through mammography, self-examination and enhanced treatment outcomes
(Breastcancer.org.au, 2020). Therefore, it can be suggested that the female population is
particularly susceptible to the condition. This can be attributed to the fact that particular risk
factors for the development of breast cancer comprise of obesity, sedentary life, and hormone
replacement therapy at the time of menopause, giving birth to children at older age, family
history of breast cancer, and early age of menarche, all of which have been found prevalent amid
females (Maas et al., 2016). The population is also more susceptible to the condition due to the
inheritance of a genetic predisposition such as, BRCA2 and BRCA1 (Kuchenbaecker et al.,
2017).
Previous research evidences have highlighted the fact that a greater socioeconomic status
is correlated with an increase risk of suffering from breast cancer, predominantly due to hormone
associated risk factors like hormonal contraceptive usage and parity (Silber et al., 2018). The
greater prevalence and incidence of breast cancer among females belonging to high
socioeconomic status can be particularly associated to reproductive factors. The increase is not
merely due to high position in the society but is related to variance in risk factors found amid
females of different income levels and educational attainment (Owusu et al., 2016). In
comparison to those who are from a lower socio economic position, those belonging to a higher
status display an increase in likelihood of consuming more alcohol, having fewer children, using
birth control contraceptives, or postmenopausal hormones, all of which make them more
vulnerable to the condition. Hence, the primary determinants of the outcome are lifestyle factors,
genetics, medical conditions like diabetes mellitus and lupus erythematosus that increase danger
of breast cancer acquisition, and early screening through mammography (Park et al., 2017).

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Nature of association- The exposure in this epidemiological literature is breast cancer
screening. It refers to the medical screening of healthy women for detection of breast cancer, in
order to accomplish an early diagnosis that helps in improving health outcomes. The most
common screening method utilizes mammography owing to its wide availability and fast
procedure. This process encompasses radiography that is used for facilitating diagnosis of a
female, who reports signs and symptoms of breast cancer (diagnostic mammography), or
preclinical screening of a female who apparently appears healthy (screening mammography)
(Rodríguez-Ruiz et al., 2019).
The outcome is disease specific mortality, and in this particular case it refers to the
number of deaths that have occurred due to breast cancer, and whether subjecting females to the
screening procedure helps in reducing this mortality rate. In this particular literature, the
population base comprises of asymptomatic adults, excluding children and pregnant females.
This suggests that the population base focuses on females who do not manifest the characteristics
signs and symptoms of breast cancer. In relation to effect size, amongst the randomised
controlled trials, decrease in all-cause mortality and disease-specific mortality, by excluding 95%
CI, the null has been found in 11% and 30% of estimates, respectively (Saquib, Saquib &
Ioannidis, 2015). Findings from the study suggested that there was a significant decrease in
disease specific mortality after the conduction of mammography for breast cancer, and the range
risk reduction was found to be within 16-45%. The relative risk estimates in relation to all cause
mortality was also extremely close to the range 0.98–1.03 (Saquib, Saquib & Ioannidis, 2015).
However, it was suggested that the documented decrease, in relation to disease specific mortality
suggest that particular benefits of screening might have been considerably overestimated.

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Evidence- There are several scholarly evidences that determined the association between
the aforementioned exposure and outcome. Though few of the studies are based on systematic
review and meta-analysis, majority of them are cohort studies, and their population base
comprises of asymptomatic females. Ali, Garnier and Humphreys (2016) evaluated the
correlation of different features with breast cancer with the use of logistic regression. The
findings suggest that there exists significant association of spatial relations with breast cancer
status (p= 0.009). It has been further elucidated that the comparative distribution of
fibroglandular and adipose tissue is intricately associated with the development of breast cancer.
In the words of Broeders et al. (2018) there occurred a significant reduction in advanced breast
cancer rate (ABCR) after introducing mandatory mammography service screening programs. Not
only did such screening program decrease distant metastasis, but also played an important role in
a reduction in the incidence of cancer. ABCR (Stage 2+) was also found to fall short by as much
as 20%, when compared to a particular region where screening was implemented much later,
thus providing evidence for a temporal association. According to Yaffe et al. (2018) incidence
related mortality leads to a quantification of cancer distribution, and the number of life years that
have been lost. On investigating temporal distribution of the burden of the disease it was found
that, in absence of screening, an estimated 70% burden of breast cancer associated death occurs
from 45-75 years of age. 61.8 years was found to be the mean age of breast cancer detection that
would prove fatal. 55 years was the mean detection age, in contrast to the number of life years
that get lost from the affected person, thus demonstrating a loss by approximately 6.8 years.
Answer 2
Key methodological limitations- Bleyer, Baines and Miller (2016) mentioned that
mammography screening cannot be cited as the major reason for reduction in breast cancer

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mortality in North America and Europe. Though Saquib, Saquib and Ioannidis (2015) failed to
elucidate any temporal and spatial association between the exposure and the outcome, it was
suggested that lack of sensitivity and specificity of the screening test for detecting the disease,
during the early stages might contributed to its poor performance. Another major limitation can
be associated with the lack of any substantially effective treatment for the aforementioned
disease. Additionally, unfavourable risk benefit ratio of the complete mammography screening
and cancer treatment procedure also adds to the limitations. The results are likely to be
confounded, since there are several factors like continent of birth, obesity, density on
mammogram, cancer history in one particular breast, smoking, benign disease in the
breast, breast cancer family history in a first degree relative, and consumption of not less than
two alcoholic drinks each day, all of which play an important role in determining the disease
specific mortality (Camacho, Anderson & Kimmick, 2019).
Conclusion- Thus, it can be concluded that the evidences presented above are not
consistent owing to the fact that while some evidences elaborate on the effectiveness of
mammography screening in preventing risk of breast cancer, and decreasing this is specific
mortality, others focus on the lack of sensitivity and specificity of the screening procedure,
which failed to create an impact on the mortality rate. Therefore, there exist limitations in the
establishment of a causal association between screening procedure and disease specific mortality,
in relation to breast cancer. Synthesis of random evidences, rather than data from case control or
cohort studies also added to the shortcomings. Taking into consideration the different reasons
behind the problematic documentation of a decrease in all cause mortality, evidences from large
randomised controlled trials are collected. Use of broad search terms in the electronic databases
might have also resulted in exclusion of significant articles, in addition to lack of evidence on

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efficacy of one particular screening method over other. Hence, there is a need to select an
appropriate study design in order to determine effectiveness of different screening tests in
reducing all cause and disease specific mortality for breast cancer.

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References
Ali, M. A., Garnier, M., & Humphreys, K. (2016, January). Spatial Relations of Mammographic
Density Regions and their Association with Breast Cancer Risk. In MIUA (pp. 169-174).
Bleyer, A., Baines, C., & Miller, A. B. (2016). Impact of screening mammography on breast
cancer mortality. International journal of cancer, 138(8), 2003-2012.
Breastcancer.org.au. (2020). Statistics. Retrieved from https://www.breastcancer.org.au/about-
breast-cancer/statistics.aspx
Broeders, M. J. M., Allgood, P., Duffy, S. W., Hofvind, S., Nagtegaal, I. D., Paci, E., ... &
Bucchi, L. (2018). The impact of mammography screening programmes on incidence of
advanced breast cancer in Europe: a literature review. BMC cancer, 18(1), 860.
Camacho, F., Anderson, R., & Kimmick, G. (2019). Investigating confounders of the association
between survival and adjuvant radiation therapy after breast conserving surgery in a
sample of elderly breast Cancer patients in Appalachia. BMC cancer, 19(1), 1-11.
Cancer Australia. (2020). Breast cancer in Australia statistics. Retrieved from https://breast-
cancer.canceraustralia.gov.au/statistics
Kuchenbaecker, K. B., Hopper, J. L., Barnes, D. R., Phillips, K. A., Mooij, T. M., Roos-Blom,
M. J., ... & Goldgar, D. E. (2017). Risks of breast, ovarian, and contralateral breast cancer
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Kyu, H. H., Bachman, V. F., Alexander, L. T., Mumford, J. E., Afshin, A., Estep, K., ... & Cercy,
K. (2016). Physical activity and risk of breast cancer, colon cancer, diabetes, ischemic

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Yaffe, M. J., Mittmann, N., Alagoz, O., Trentham-Dietz, A., Tosteson, A. N., & Stout, N. K.
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