Critical Appraisal: Beverages and Endometrial Cancer Relationship

This report provides a critical appraisal of a case-control study investigating the relationship between tea and coffee consumption and the risk of endometrial cancer (EC). The study, conducted at the Roswell Park Cancer Institute, involved 541 women with EC and 541 controls. The report examines the study design, methodology, and statistical analysis, highlighting the findings that consumption of coffee and tea is associated with a reduction in EC risk. The report also assesses the internal and external validity of the study, discussing potential biases and limitations. The report further analyzes the causality inferences and explores the implications of the findings for different populations. The study found that consuming more than two cups of coffee per day recorded a twenty-eight percent (28%) reduction in EC risk in comparison to non-drinkers and women who took more than two cups of tea per day registered a forty-four percent (44%) reduction in EC risk in comparison to non-drinkers. The report concludes with an overview of the study's strengths and weaknesses, and its relevance to public health.

Running head: ASSOCIATION BETWEEN BEVERAGES AND ENDOMETRIAL CANCER 1
Critical Appraisal: Relationship between Tea and Coffee Consumption with Endometrial Cancer
(EC)
Student’s Name
Institutional Affiliation

ASSOCIATION BETWEEN BEVERAGES AND ENDOMETRIAL CANCER 2
Introduction
The study by McCann, Yeh, Rodabaugh, & Moysich (2009) explore the relationship
between tea and coffee consumption a reduction in endometrial cancer (EC). Several research
projects have examined the link between endometrial cancer and diet. However, few studies have
narrowed down on tea and coffee (Merritt et al., 2015). Therefore, McCann et al., 2009 discusses
the association between the consumption of beverages and the risk of endometrial cancer. The
drinks under study include decaffeinated coffee, caffeinated coffee, and tea. The investigators
researched from the year 1982 to 1998. The study involved 541 women having cancer and other
541 women without the complication to act as a control to the investigations.
This essay will provide an overview of the study by McCann et al., 2009, exploring the
study design, target population, methodology, and statistical analysis. It will also appraise the
results and findings of the research question. The write-up will also evaluate the internal validity
of the paper. Furthermore, it will explore the causality issues in the epidemiology research paper.
Finally, the essay will analyze the external validity of the document to other target groups.
Study Overview
Study design, Population, Methodology, and Statistical analysis
The investigators applied Randomized control method as the study design. The study
population involved 1082 women. 541 individuals involved had endometrial cancer, while the
other 541 acted as a control to the study. The researchers obtained the study population from the
Roswell Park Cancer Institute situated in New York’s Buffalo. The investigators issued
epidemiologic questionnaires to the randomly selected women at the cancer institute. 50% of
those who received the surveys filled and returned them to the investigators. The questionnaires
covered a variety of issues ranging from alcohol consumption to diet.

ASSOCIATION BETWEEN BEVERAGES AND ENDOMETRIAL CANCER 3
The investigators used the SAS method to analyze the data received from the women.
What the SAS used was compatible with version 9.1 of Windows (Breßler, Kohlbrecher, &
Thünemann, 2015). The researchers limited the data analysis to questionnaires with complete
information about the relationship between tea, decaffeinated coffee, and coffee and endometrial
cancer. The investigators applied the t-test to access the continuous variables. However, the
researchers used chi-square to access the categorical variables. The study categorized beverage
consumers as follows: those who do not consume beverages, a half cup per day, and one to two
cups per day. Furthermore, those individuals who drink less than two cups of beverages per day
had their category.
Findings
Women who consumed more than two cups of coffee per day recorded a twenty-eight
percent (28%) reduction in EC risk in comparison to nondrinkers (McCann et al., 2009).
However, the researchers did not record an association between cancer and consumption of
decaffeinated coffee. Women who took more than two cups of tea per day registered a forty-four
percent (44%) reduction in EC risk in comparison to non-drinkers. Furthermore, the women who
took more than four cups of both tea and coffee registered a fifty-three percent (53%) reduction
in EC risk.
Discussion
The authors begin by acknowledging the fact that the relationship between endometrial
cancer and the beverages has been inadequately covered in the previous literature. The findings
indicate that the consumption of coffee and tea reduces the risks of getting endometrial cancer.
Tea consumption decreases the risk of tumor more than coffee intake by the case and the control.
Furthermore, consuming more than four cups of both beverages reduces the risk of cancer more

ASSOCIATION BETWEEN BEVERAGES AND ENDOMETRIAL CANCER 4
than taking an individual drink. However, the study does not indicate the association between
endometrial cancer and decaffeinated coffee. Beverages contain phytochemicals which affect
carcinogenesis (Singh, Prateeksha, Rawat, Bhagat, & Singh, 2017). Additionally, tea contains
elevated amounts of theaflavins and catechins; hence making it more viable than coffee (Zhou et
al., 2016).
Appraisal of Internal Validity
All in all, this is a time-sensitive and well-designed research, offering essential literature
on the relationship between endometrial cancer and beverage consumption. The data allows the
reader to understand the association between tea, coffee, and decaffeinated coffee and cancer
(McCann et al., 2009). The reliability and the validity of the instruments gauging the covariates
are robust and have few non-differential errors. Therefore, the study is a valuable source of
information on beverages versus cancer (Yeganeh, Harrison, Vincent, Teede, & Boyle, 2018).
The investigators have presented the results using open tables. Chance variation cannot
affect the data since the information on beverage consumption by women with or without EC is
readily available (Forero et al., 2018). Selection bias is another barrier that can affect the validity
of given research (Taylor, Fossey, & Kielhofner, 2017). Preference can be regarding gender,
weight, or even skin color. However, the authors consider the common variables in endometrial
cancer research like higher BMI, application of OC, and HRT among cases in comparison to the
controls. Therefore, the above considerations eliminate the aspect of selection bias. Additionally,
endometrial cancer only affects women; therefore, gender bias is non-existent since the controls,
and the cases are all women.
Apart from the issues of selection bias, confounding concerns are also significant threats
of research findings (Gallego et al., 2015). The extensive data on the epidemiology of EC

ASSOCIATION BETWEEN BEVERAGES AND ENDOMETRIAL CANCER 5
permitted the researchers to provide reasons for confounders in their analyses. However, some
drawbacks jeopardize the internal validity of the study results. The exposure and the
characteristics of the general public can differ from those of individuals at the Roswell Institute
of Cancer. Secondly, the researchers lacked accurate data on the size of beverage consumption.
The investigators did not note the differences in the cup sizes that the women used to consume
the beverages.
The control, just like the case women were patients of the Roswell health facility.
Therefore, the control may have altered their diet before administration to the hospital. Similarly,
there is a possibility that the patients of endometrial cancer would have also altered their diet
before visiting the health facility. The alteration in food is a possible cause of attenuation in the
estimates observed by the investigators (Obermair et al., 2016). Apart from the mentioned
limitations, the research possesses internal validity.
Appraisal of Causality Inference
The research by McCann et al., 2009 is a case-control study that examines the
relationship between the consumption of beverages and endometrial cancer. Several studies have
explored the relationship between the complication and diet. However, few investigations like
this one by McCann et al., 2009 have investigated the association between the disease and
beverages like coffee and tea. Therefore, the study confirms that the consumption of beverages
reduces the risk of contracting endometrial cancer (Ellis, 2017). The findings also confirm a
dose-response association between exposure and outcome. The results indicate that women who
are consuming beverages are at a lower risk of endometrial cancer than those who do not take
drinks. The researchers collected data on beverage consumption before getting the outcome; this
approach supports a hypothesis on the causal association.

ASSOCIATION BETWEEN BEVERAGES AND ENDOMETRIAL CANCER 6
The data provided in the study proves the causal association between beverages and
endometrial cancer. There is also a relationship between tea consumption and endometrial cancer
in obese women. Additionally, the intake of coffee work best for women having normal weight.
Therefore, during experimentation, the researchers should suggest tea to overweight women and
coffee to those with a healthy weight. Matching the beverage with the different sizes leads to
desirable results. Apart from drinks, obesity is also a risk factor for the complication (Brown,
McNair, Szalacha, Livingston, & Hughes, 2015). An increase in body weight increases the
chances of developing endometrial cancer. Eating fatty and carbohydrate-rich food elevates the
possibilities contacting the complication. However, eating fat-free food decreases the chances of
a woman to develop cancer. Therefore, obesity also has an association with endometrial cancer.
The researchers studied the link between coffee, tea, and endometrial cancer in a limited
environment which is at the Roswell hospital. EC patients outside the hospital may have
different exposures and personal characteristics towards the complication. Therefore, there is a
possibility that, patents at home may not record a reduction in the EC risk due to beverage
intake. Additionally, the researchers did not consider the size of beverage cups used by various
cases and controls (O'Brien, & Sali, 2017). It is possible that those that used big cups recorded a
lower cancer risk than the individuals who used small cups. The possibility can create room for
hypothesis modification. The investigators also used controls from the hospital. It is possible that
commands from the general public can record different results from those at the health facility.
Appraisal of External Validity
The study has various strengths and limited drawbacks which makes it valid for
populations outside the USA. The authors indicate that a recent study confirmed the relationship
between beverages and cancer in Japanese women (McCann et al., 2009). Therefore, Japan and

ASSOCIATION BETWEEN BEVERAGES AND ENDOMETRIAL CANCER 7
other Asian countries can rely on research to manage the disease. Additionally, tea and coffee are
beverages that individuals consume all over the world (Takechi et al., 2018). The study by
McCann et al., 2009 lacks gender bias as cancer only affects women. The research investigates
the impacts of beverage consumption in women with the disease and those without the
complication. However, the study is limited to a hospital set-up as it bases on women at the
Roswell Institute of cancer. Therefore, it may not have similar impacts to the general public.
The sample size is large, giving a simplified representation of the total population. The
researchers randomly selected 541 women with EC and another 541 without the complication to
act as a control. Apart from the sample size, the investigators considered other essential
parameters; hence, qualifying the application of the research to all parts of the world. The study
finds the effects of beverage consumption among obese and non-obese women. The analysis also
considers the impacts of coffee and tea on young and old women who are past their menopause.
The findings also investigate the effect of education on the relationship between beverages and
endometrial cancer (Pálsdóttir et al., 2016). The results also consider the impact of the study on
the smoking history of both the cancer patients and the control women. Therefore, the broad
spectrum of the research makes it valid for worldwide usage.
Apart from the various strengths, a few drawbacks can make other researchers question
the global outlook of the research. The investigators based their study on patients of Roswell
Cancer Park Cancer Institute in New York. Additionally, the researchers are all from Buffalo in
New York. Readers from outside New York can easily assume that the findings are only viable
within the capital city. Certain individuals do not take coffee and tea (Shivappa, Steck, Hurley,
Hussey, & Hébert, 2014). Therefore, the researchers should address such groups of persons. The

ASSOCIATION BETWEEN BEVERAGES AND ENDOMETRIAL CANCER 8
researchers conducted their study between the years 1982 to 1998. A section of readers can view
the research as an old study and fail to apply it in the current century.
Conclusion
Despite the few challenges facing the study, the authors succeed in explaining the
relationship between beverages and endometrial cancer. The researchers apply the randomized
control design to conduct the investigation. The study population involves 541 EC patients and
another 541 control women from the Roswell Park Cancer Institute. The research applies
questionnaires to collect data from the case and the control women. Statistical analysis is through
the SAS that the researchers use Windows 9.1 version to achieve. The findings show that the
consumption of coffee and tea reduces the risk of endometrial cancer. The researchers further
discuss the beverages reduces the chances of contacting the complication.
The findings are valid to the research on the relationship between endometrial cancer and
beverages. The study lacks any form of bias like the gender or sample size questions. The EC is
limited to women, at the same time, the sample population is women. Confounding concerns are
not an issue since extensive data exist on consumption of beverages by women. The investigators
also exhibit a causal association between coffee, tea, and endometrial cancer. However, there is
also an association between obesity and EC. Readers can apply the findings worldwide; since
coffee and tea are global beverages.

ASSOCIATION BETWEEN BEVERAGES AND ENDOMETRIAL CANCER 9
References
Breßler, I., Kohlbrecher, J., & Thünemann, A. F. (2015). SASfit: a tool for small‐angle scattering
data analysis using a library of analytical expressions. Journal of applied
crystallography, 48(5), 1587-1598.
Brown, R., McNair, R., Szalacha, L., Livingston, P. M., & Hughes, T. (2015). Cancer risk
factors, diagnosis and sexual identity in the Australian Longitudinal Study of Women's
Health. Women's health issues, 25(5), 509-516.
Ellis, J. (2017). The Psychosocial impact of food and nutrition on hospitalized oncological
palliative care patients and their carers. pp. 67-98
Forero, R., Nahidi, S., De Costa, J., Mohsin, M., Fitzgerald, G., Gibson, N., ... & Aboagye-Sarfo,
P. (2018). Application of four-dimension criteria to assess the rigor of qualitative
research in emergency medicine. BMC health services research, 18(1), 120.
Gallego, B., Walter, S. R., Day, R. O., Dunn, A. G., Sivaraman, V., Shah, N., ... & Coiera, E.
(2015). Bringing cohort studies to the bedside: a framework for a ‘green button to support
clinical decision-making. Journal of comparative effectiveness research, 4(3), 191-197.
McCann, S. E., Yeh, M., Rodabaugh, K., & Moysich, K. B. (2009). Higher regular coffee and tea
consumption are associated with reduced endometrial cancer risk. International journal
of cancer, 124(7), 1650-1653.
Merritt, M. A., Tzoulaki, I., Tworoger, S. S., De Vivo, I., Hankinson, S. E., Fernandes, J., ... &
Dahm, C. C. (2015). Investigation of dietary factors and endometrial cancer risk using a
nutrient-wide association study approach in the EPIC and Nurses' Health Study (NHS)
and NHSII. Cancer Epidemiology and Prevention Biomarkers, 24(2), 466-471.

ASSOCIATION BETWEEN BEVERAGES AND ENDOMETRIAL CANCER 10
Obermair, A., Brennan, D. J., Baxter, E., Armes, J. E., Gebski, V., & Janda, M. (2016). Surgical
safety and personal costs in morbidly obese, multimorbid patients diagnosed with early-
stage endometrial cancer having a hysterectomy. Gynecologic oncology research and
practice, 3(1), 1.
O'Brien, K., & Sali, A. (2017). A Clinician's Guide to Integrative Oncology: What You Should
Be Talking About with Cancer Patients and Why. Springer. pp. 78-90
Pálsdóttir, B., Barry, J., Bruno, A., Barr, H., Clithero, A., Cobb, N., ... & Strasser, R. (2016).
Training for impact: the socio-economic implications of a fit for purpose health
workforce on communities. Human resources for health, 14(1), 49.
Shivappa, N., Steck, S. E., Hurley, T. G., Hussey, J. R., & Hébert, J. R. (2014). Designing and
developing a literature-derived, population-based dietary inflammatory index. Public
health nutrition, 17(8), 1689-1696.
Singh, B. N., Prateeksha, Rawat, A. K. S., Bhagat, R. M., & Singh, B. R. (2017). Black tea:
Phytochemicals, cancer chemoprevention, and clinical studies. Critical reviews in food
science and nutrition, 57(7), 1394-1410.
Taylor, R. R., Fossey, E., & Kielhofner, G. (2017). Selecting the Research Method. Kielhofner's
Research in Occupational Therapy: Methods of Inquiry for Enhancing Practice, 119.
Takechi, R., Alfonso, H., Harrison, A., Hiramatsu, N., Ishisaka, A., Tanaka, A., ... & Lee, A. H.
(2018). Assessing self-reported green tea and coffee consumption by food frequency
questionnaire and food record and their association with polyphenol biomarkers in
Japanese women. Asia Pacific journal of clinical nutrition, 27(2), 460.

ASSOCIATION BETWEEN BEVERAGES AND ENDOMETRIAL CANCER 11
Yeganeh, L., Harrison, C., Vincent, A. J., Teede, H., & Boyle, J. A. (2018). Effects of lifestyle
modification on cancer recurrence, overall survival and quality of life in gynecological
cancer survivors: A systematic review and meta-analysis. Maturitas, 111, 82-89.
Zhou, Q., Li, H., Zhou, J. G., Ma, Y., Wu, T., & Ma, H. (2016). Green tea, black tea
consumption, and risk of endometrial cancer: a systematic review and meta-analysis.
Archives of gynecology and obstetrics, 293(1), 143-155.