Coffee Consumption and Cancer Risk

This assignment analyzes two research studies investigating the relationship between coffee consumption and the risk of colon and colorectal cancer. Students evaluate the findings, identify potential biases in each study (like self-reported data and selection bias), and compare the methodologies used by both researchers. The analysis also considers the strengths and limitations of each study design.

Running head: EPIDEMIOLOGICAL ANALYSIS ASSIGNMENT
Epidemiological analysis assignment
Name of the student:
Name of the university:
Author note:

1EPIDEMIOLOGICAL ANALYSIS ASSIGNMENT
Table of Contents
Part A: 2
Question a: 2
Question b: 2
Question c: 2
Question d: 3
Question e: 3
Question f: 3
Question g: 4
Question h: 4
Question i: 4
Question j: 4
Part B: 5
Question a: 5
Question b: 5
Question c: 5
Question d: 6
Question e: 6
Question f: 6
Question g: 6

2EPIDEMIOLOGICAL ANALYSIS ASSIGNMENT
Part C: 8
References: 9

3EPIDEMIOLOGICAL ANALYSIS ASSIGNMENT
Part A: For article by La Vecchia et al., 1989
Question a:
The article opted for the qualitative exploratory study design taking the help of case control
analysis.
The primary outcome of the study had been to explore the overall risk factors, both
multivariate and relative, due to excessive caffeine consumption and its impact on the digestive
tract carcinogenesis.
Question b:
The study took into consideration different cases involving 1944 control subjects in total,
with 1334 males and 610 females. Out of the total number of control subjects, 38% were
admitted due to traumatic conditions, 15% had non- traumatic orthopaedic disorders, 34% had
had acute surgical conditions, and 13% had other unrelated illnesses.
Question c:
The appropriateness of the control samples can be justified by the fact that none of the
control subjects had neither existent malignancy nor digestive tract disorders; hence the outcome
of the research can be authentically explored.
The limitations can be the fact that investigators excluded all chronic and the digestive tract
disorder from the comparison group.

4EPIDEMIOLOGICAL ANALYSIS ASSIGNMENT
Question d:
There had been 455 case subjects with colon cancer, and the multivariate risks associated
with coffee consumption was 0.64. However, the research study discovered significant inverse
trends in the risk factor in relation to coffee consumption in case of colon cancer recipients. The
strength of the control set for colon cancer had been the fact that there had been no noticeable
interaction between coffee consumption with references to colon cancer, the strengths are that it
provides an opportunity for obtaining a pattern of risks for different digestive tract neoplasms,
for which the stat for protection was much higher than any other cancer type. The limitations are
that the investigators excluded all chronic and the digestive tract disorder from the comparison
group.
Question e:
Use of coffee is the only exposure factor which is used to show a positive relationship with
the colorectal cancer.
Question f:
Results demonstrate that there were noteworthy inverse patterns detected for coffee
consumption in relation to the possibility of the colon cancer (multivariate relative hazard, 0.64)
and rectum (relative hazard, 0.66). The protection however was higher in case of the colon
cancer and less apparent in case of rectal cancer. Moreover, in case of the rectal cancer, the
neoplasm protection was restricted to males, of younger age groups. The relationship between
coffee drinking and diseases of the colon and rectum was additionally inspected in particular
strata of age, sex, and other major covariates.

5EPIDEMIOLOGICAL ANALYSIS ASSIGNMENT
Question g:
The bias which I can found after reading this study is that the investigators had taken 1334
males and 610 females. The type of in this article is the sampling bias.
Question h:
A bias in the case control study is harmful as it may cause inaccuracy in the assessment. It
also causes harms to the relationship and results in the disturbance in the relationship between
the risk factor and the disease. The sampling bias is a type of systemic error caused due non-
random selection of the population, which causes the differentiation in the selection of the
sample.
Question i:
Malignancy is associated with many risk factors, such as smoking and drinking which had
been adjusted in the result of the research study. However, the impact of smoking and drinking
had been omitted as confounders due to the fact that both these factors have already been
established as carcinogenic. This study explored the effect of coffee consumption and its relation
to the process of carcinogenesis of the digestive tract.
Question j:
As the results of the study clearly indicated at the lack of any association of coffee
consumption and increase in the risk factor with carcinogenesis, I trust the verdict unequivocally.

6EPIDEMIOLOGICAL ANALYSIS ASSIGNMENT
Part B: for article by Phillips et al., 1985.
Question a:
The research design of the study is qualitative cohort analysis.
Question b:
This study explores the correlation between consumption of coffee along with meat, milk,
cheese, eggs and green salad with possibility of fatal colon or colorectal cancer. The participants
those were selected are 27,829 peoples from the California Seventh-Day Adventists. They were
followed up for 21 years and was found that cheese, meat, milk or green salad does not have any
relationship with the cancer but use of egg and coffee causes cancer. The primary outcome of the
study was to discover the influence of dietary choices involving the said components on the
mortality rates associated with colon or colorectal cancer.
Question c:
There were two groups of exposure of colorectal cancer studied in the article, light and heavy
exposure. The difference as evaluated in terms of relative risks. For meat, cheese, milk and green
salad, there were no relative risks discovered. In case of eggs, the relative risk had been higher
for fatal colon cancer; coffee use was associated with the risks for both colon and colorectal
cancer. The strength of the exposure analysis was that it had Adventist population as sample and
evaluated the differential exposure with dose-response relationship. The limitations were the use
of self-administered questionnaires, accuracy of the actual cause of death, and incidence rates of
colorectal cancers.

7EPIDEMIOLOGICAL ANALYSIS ASSIGNMENT
Question d:
Results indicated that lack of any significant relationship between the use of meat or poultry
and death from either colon or rectal cancer considered alone or in combination. Consumption of
eggs was associated with fatal colon cancer, with relative risks 1.6 and 1.7 for males and females
respectively. Coffee consumption was associated with both colon and colorectal cancer
especially for males with a relative risk of 3.5.
Question e:
There is a significant bias in the study, the questionnaires were self administered which
opens up the possibility of extreme bias, where as recall bias has also been associated with the
study.
Question f:
The types of bias for a cohort study are selection bias, follow up bias and preventing loss to
follow up bias. Selection bias may occur if the choice of the subjects in a cohort study is not
related to the topic. The only way for preventing the loss to follow up is by maintaining the
follow up rates.
Question g:
According to Vecchia et al., cases and controls originated from well practically identical
catchment territories, they were met in a comparable setting. It has been appeared, for example,
that patients conceded for unending illnesses tend to report bring down espresso utilization than
those in healing center for intense conditions. While Philips and Snowdon, trust that Coffee
utilize was the main presentation variable which reliably demonstrated a significant positive
association with both colon and rectal growth in the two guys and females.

8EPIDEMIOLOGICAL ANALYSIS ASSIGNMENT
Part C:
There is a significant difference between the findings of both studies, whereas the study by
Vecchia et al indicated coffee consumption to be completely unrelated with the possibility of
colon cancer, the study by Phillip et al indicated coffee to be a significant risk factor for colon
and colorectal cancer. However, the difference in the findings in both the article can be due to
the exposure statistics, where the article by Vecchia et al only concentrated on the consumption
of coffee, the one by Phillip et al, included several other variables as risk factors which may have
clouded the verdict to some extent. Moreover the sampling design is also a bit different in both
of the studies, the study by Vecchia et al, eliminated all possible confounding factors to ensure
that minimal bias is introduced in the article. Whereas in the article by Phillip et al, the sampling
population had been Adventist and the exposure was studied in terms of dose response, hence the
verdict can be different due to the introduction of dose-response mode of evaluation as well.

9EPIDEMIOLOGICAL ANALYSIS ASSIGNMENT
References:
La Vecchia, C., Ferraroni, M., Negri, E., D'Avanzo, B., Decarli, A., Levi, F., & Franceschi, S.
(1989). Coffee consumption and digestive tract cancers. Cancer Research, 49(4), 1049-
1051.
Phillips, R. L., & Snowdon, D. A. (1985). Dietary Relationships With Fatal Colorectal Cancer
Among Seventh-Day Adventists 2. Journal of the National Cancer Institute, 74(2), 307-
317.