meta analysis ouput

8/2/2019 Meta Analysis Ouput

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A META-ANALYSISBANIQUED, Charmaine Acosta

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TABLE OF CONTENTS

I. TITLE.....2

VITAMIN C and BREAST CANCER RISK

II. PROBLEM PRESENTATION.........2

This paper discusses the association between vitamin C use and incidence of breast cancer. Is

there a significant outcome between Vitamin C intake and risk of having breast cancer?

III. PURPOSE...2

The purpose of this meta-analysis is to determine if there is a consistent result of the researches

that had been already made. In this case, we could conclude without any hesitance especially so

that we are talking about the big C which is a grave illness and that is unfortunately very notuncommon.

IV. BACKGROUND..2

Cancer is a leading cause of death worldwide, accounting for 7.6 million deaths (around 13% of

all deaths) in 2008 .Lung, stomach, liver, colon and breast cancer cause the most cancer deaths

each year. The most frequent types of cancer differ between men and women.

V. DISCUSSION.....4

Most people think that vitamins can help treat or decrease the risk of having cancer, becausesome vitamins, such as vitamin C, are antioxidants that help clear oxidants that cause cancer.

(Mirkin, 2002)

VI. CONCLUSION......6

Among the prospective epidemiologic studies conducted on Vitamin C and breast cancer to

date,

VII. RECOMMENDATIONS...6

Findings from these studies are of concern and merit further research using RCT since this is

the best study design for looking at the effects of

IX. APPENDICES....7

VIII. REFERENCES .............................................................................................................. 11


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I. TITLEVITAMIN C and BREAST CANCER RISK

II. PROBLEM PRESENTATIONThis paper discusses the association between vitamin C use and incidence of

breast cancer. Is there a significant outcome between Vitamin C intake and risk of

having breast cancer? Studies made had been inconclusive because of the contradicting

results of some researches.

III. PURPOSEThe purpose of this meta-analysis is to determine if there is a consistent result of

the researches that had been already made. In this case, we could conclude without any

hesitance especially so that we are talking about the big C which is a grave illness and

that is unfortunately very not uncommon.

Hence, this opens the windows for further researches to be made to look for risk

factors or any contributory factors, like taking into account the things we do currently

that we might think are ways of taking responsibility of our own health, or it is just what

we think so as latest research findings will come into picture and sometimes, resultsdefies what we think has established and accepted scientific basis at present.

IV. BACKGROUNDCancer is a leading cause of death worldwide, accounting for 7.6 million deaths

(around 13% of all deaths) in 2008 .Lung, stomach, liver, colon and breast cancer cause

the most cancer deaths each year. The most frequent types of cancer differ between men

and women. (www.google.com)

Breast cancer is the second most common type of cancer and the second leading

cause of cancer-related deaths. One in eight women in the United States will develop

breast cancer during her lifetime.

According to the American Cancer Society (ACS), approximately 200,000 new

cases of breast cancer are diagnosed each year in the United States, and the disease

causes about 41,000 deaths annually. (www.google.com)


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Breast cancer is the most common cancer diagnosed in the United States, after

skin cancer. It is the second leading cause of cancer deaths in women today, after lung

cancer. According to the American Cancer Society, more than 230,000 women will be

diagnosed with breast cancer annually in the United States, and more than 39,000 will die

from the disease.

Breast cancer rates are on the decline, according to the Society. Deaths from

breast cancer have decreased by about 2 percent since 1990, likely from earlier detection

and advances in treatment. (www.wikipedia.com)

According to Gandini et.al ( 2000), although a pattern is emerging among

epidemiological studies showing women with diets high in fruit and vegetables have a

decreased risk of breast cancer, the results are not consistent. She also investigates

carotenoids and vitamin C as these micronutrients may protect against breast cancer due

to their role in antioxidant defense.

However, current studies show that Vitamin C mega dose and IV Vitamin C is

beneficial for breast cancer patients on chemotherapy and radiation therapy. So that if

Vitamin C was effective for supplementary treatment, how about the usage of vitamin C

for prevention of breast cancer?

In a 2005 study, an NIH Vitamin C study, a high dose of vitamin C, administered

to 10 cancer and 4 normal human cell types, effectively killed 5 of the cancer lines and

did not affect the normal cells. Cancer cell death was absolutely dependent on the

formation of hydrogen peroxide, a chemical that can kill cancer cells. Therefore,

intravenous (IV) vitamin C may be a pharmacologic pro-drug for the formation ofhydrogen peroxide. (Chen, 2005)

In a March 2006 study, three case studies of patients with advanced cancer, who

were given high doses of intravenous vitamin C and lived longer than expected, were

analyzed in accordance with the National Cancer Institute's Best Case Series Guidelines.

The fact that the patients had unexpectedly long survival times increases the clinical

plausibility that vitamin C may have a benefit. It is now known that high-dose

intravenous - but not oral vitamin C therapy - results in plasma concentrations of about

14,000 micromole per liter. Oral doses result in plasma concentrations of at best 220

micromole per liter. The high-dose IV levels of vitamin C are toxic to some cancer cells,but not to normal cells. This study concludes that the role of high-dose

intravenous vitamin C therapy in cancer treatment should be reassessed. (Padayatty J.,

2006).

It is also worth considering the fact that, according to Cho et. al, (2003), Vitamin

C have been hypothesized to reduce the risk of breast cancer by its role as an anti-

oxidant. A regulator of cell differentiation and a modulator of DNA synthesis.
http://www.imaginis.com/breast-health/what-is-breast-cancer-2http://www.imaginis.com/breast-health/what-is-breast-cancer-2


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Many women use multivitamins (that also contain vitamin C) in the belief that

these supplements will prevent chronic diseases such as cancer and cardiovascular

disease. However, whether the use of multivitamins affects the risk of breast cancer is

unclear. (Larsson, 2010).

V. DISCUSSIONMost people think that vitamins can help treat or decrease the risk of having

cancer, because some vitamins, such as vitamin C, are antioxidants that help clear

oxidants that cause cancer. (Mirkin, 2002). In line with this, here in the Philippines, use

of multivitamins and Vitamin C supplements ( as well as the natural source) are well-

utilized especially so because Vitamin C is readily available and ease of accessibility

cannot be denied. With the advent of many emerging diseases today, people start taking

responsible actions towards their own health. It is also with the believe that Vitamin C iscontibutory for the strengthening of the immune system to wards-off diseases including

cancer.

For us to be able to look for the concrete evidence then that Vitamin C do have an

effect on the risk of having breast cancer whether positively or negatively, this meta-

analysis have been possible basing from the 8 cohort studies found that are at least

closely-related, (as presented in the succeeding paragraphs).

Studies show that still, up to the present, the results are not consistent. Amongst

the eight studies only one study resulted into positive outcome. The study entitled

Dietary Carotenoids And Vitamin A, C, And E And Risk Of Breast Cancer (see table 4)

concluded that increasing total Vitamin C from foods was strongly inversely associated

with breast cancer risk. And that consumption of fruits and vegetables high in specific

vitamins may reduce breast cancer risk. This is a cohort study using food frequency

questionnaire and within 14 years follow-up period they founded 2,697 breast cancer

incidents out of the 83, 234 women living in the United States.

Another research was conducted on the Dietary Fiber, Vitamins A, C, E, And

Risk Of Breast Cancer: A Cohort Study. This had been after 5 years of follow-up

study and the result was statistically non-significant reduction in risk was observed withincreasing dietary intake of Vitamin. C. There were 519 breast cancer incidents56, 837

Canadian women. See table 1. (Rohan, 1993)

In a study,A Prospective Study Of The Intake Of Vitamins C, E, And A And

The Risk Of Breast Cancer, result showed large intakes of vitamin C did not protect

women in the study from breast cancer because 1439 women was diagnosedof breast


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cancer out of the 89,494 ofAmerican women This is a cohort studyusing food frequency

questionnaire and follow up study was done within 8 years of follow-up. See table 2.

(Hunter, 1993)

In another study entitled Vitamins C & E, Retinol, Beta-Carotene And Dietary

Fibre In Relation To Breast Cancer Risk: A Prospective Cohort Study, found out that

Vitamin C intake showed non-significant inverse association with breast Ca risk and there

is a small risk reduction observed with increasing dietary Vitamin C intake They had

recorded 650 breast cancer incident out of 62,573 women from Netherlands. The

instrumentation used was food frequency questionnaire and had a follow-up mean of4.3

years. See table 3. (Verhoeven, 1997)

In Pre-Menopausal Intakes Of Vitamins A, C, And E, Folate And

Carotenoids, And Risk Of Breast Cancer, this is also a cohort study with 8 years

follow-up studyused food frequency questionnaire and found out that no evidence thathigher intake of Vitamin C in early adult life reduce risk of breast cancer. There were

714 breast cancer incidents recorded out of90,655 US women. See table 5. (Cho, 2003).

In the study, A Prospective Study Of Multivitamin Supplement Use And Risk

Of Breast Cancer, observed inverse association that not be explained by vitamin C

contained in multi-vitamins. This is a cohort study using food frequency questionnaire

and followed up in 10 years. Of the 37,920 US women enrolled in the study, there were

1,171 breast cancer incidents diagnosed. See table 6. (Ishitani, 2008)

In the research entitled, Dietary Beta Carotene, Vitamin C And E Intake And

Breast Cancer Risk In The European Prospective Investigation Into Cancer And

Nutrition ((EPIC), the result was that dietary intake of beta-carotene, vitamin C & E was

not associated with breast cancer risk. This cohort study used food frequency

questionnaire and have a follow-up mean within 8.8 years. There was a recorded 7,502

breast cancer incident among 345,995 women. See table 7. (Nagel, 2009)

Multi-Vitamin Use And Breast Cancer Incidence In A Prospective Cohort Of

Swedish Women is a cohort study with a 35, 329 women and from them, 974 breast

cancer incident was diagnosed with breast cancer upon follow-up within 9.5 years. Theresult was that no significant increase in risk of breast cancer in women who took specific

supplements (Vitamin C) than those who did not take. See table 8. (Larsson S. C., 2010)


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VI. CONCLUSION

Among the prospective epidemiologic studies conducted on Vitamin C and breastcancer to date, there is no association that is consistent, strong and statistically significant

data that shows that there is a significant decrease or may decrease the risk of having

breast cancer in women with the use of Vitamin C except for one study conducted.

VII. RECOMMENDATION Findings from these studies are of concern and merit further research

using RCT since this is the best study design for looking at the effects ofVitamin C and up to date, there is a very limited number of studies

conducted upon literature review.

Almost all studies conducted focused on Vitamin C during adult life and itis possible that human breast tissues may be most susceptible during early

life, particularly, before puberty.

The average follow-up time in cohort studies may be too short after startof administration to capture the role of vitamin C as an initiator or initial

preventive factor of cancer.

Further development and improvement of dietary (food components,Vitamin C) assessment instruments to adequately correct for measurement

errors if there is any

The benefits of Vitamin C amidst the conclusion given, cannot be takenfor granted and it is considerable that the use of Vitamin C for health

promotion not necessarily on breast cancer prevention is still advisable.


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VIII. APPENDICES

TITLE VARIABLES # ofPARTICIPANTS

TYPE OF

STUDYYEARS of

CONDUCTION

RESULT/FINDINGS

DietaryFiber,

Vitamins A,

C, E, And

Risk OfBreast

Cancer: A

Cohort

Study

>Vit. Cintake

>Risk of

breast cancer

>56, 837Canadian

women

>Cohort

studyusing

questionnaire

>5 years

>Statisticallynon significant

reduction in

risk was

observed withincreasing

dietary intake of

Vit. C

>519 breast

cancer incident

Table 1. (Rohan, 1993)

TITLE VARIABLES # ofPARTICIPANTS

TYPE OF

STUDYYEARS of

CONDUCTIONRESULT/FINDINGS

A

Prospective

Study Of TheIntake Of

Vitamins C,

E, And A

And TheRisk Of

BreastCancer

>Vitamin C

intake

>Risk of

breast cancer

>89,494 of

American

women

>Cohort

studyusing foodfrequency

questionnaire

>8 years

>Large intakes

of vitamin C did

not protectwomen in the

study from

breast cancer

>1439 women

was diagnosedTable 2. (Hunter, 1993)


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TITLE VARIABLES# of

PARTICIPANTS

TYPE OF

STUDY

YEARS of

CONDUCTION

RESULT/

FINDINGS

Vitamins C& E, Retinol,

Beta-Carotene

And Dietary

Fibre InRelation To

Breast

Cancer Risk:

AProspective

CohortStudy

>Vitamin Cintake

>Risk of

breast cancer

>62,573women from

netherlands

>Cohortstudyusing foodfrequency

questionnaire

>4.3 years

>Small riskreduction

observed withincreasing

dietary Vit. C

intake

>Vit. C intake

showed non-

significantinverse

association withbreast Ca risk

>650 breast

cancer incident

Table 3. (Verhoeven, 1997)

TITLE VARIABLES# of

PARTICIPANTS

TYPE OF

STUDY

YEARS of

CONDUCTION

RESULT/

FINDINGS

DietaryCarotenoids

And Vit. A,

C, And EAnd Risk Of

Breast

Cancer

>Vit. Cintake

>Risk of

breast cancer

>83, 234

women livingin the United

States

>Cohort

studyusing food

frequencyquestionnaire

>14 years

>Increasingtotal Vit. C from

foods were

stronglyinversely

associated with

breast cancer

risk

>2,697 breast

cancer incident

Table 4. (Zhang, 1999)


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TITLE VARIABLES

# of

PARTICIPANTS

TYPE OF

STUDY

YEARS of

CONDUCTION

RESULT/

FINDINGS

Pre-

Menopausal

Intakes OfVitamins A,

C, And E,

Folate And

Carotenoids,And Risk Of

BreastCancer

>Vit. C

intake

>Risk of

breast cancer

>90,655 US

women

>Cohort

studyusing foodfrequency

questionnaire

>8 years

>No evidence

that higher

intake ofVitamin C in

early adult life

reduce risk of

breast cancer

>714 breastcancer incident

Table 5. (Cho, 2003)

TITLE VARIABLES# of

PARTICIPANTS

TYPE OF

STUDY

YEARS of

CONDUCTION

RESULT/FINDINGS

A

ProspectiveStudy Of

Multivitamin

SupplementUse And

Risk Of

Breast

Cancer

>Multi-

vitamins---Vit. C intake

>Risk of

breast cancer

>37,920 US

women

>Cohort

studyusing food

frequency

questionnaire

>10 years

>Observed

inverseassociation may

not be

explained byvitamin C

contained in

multi-vitamins

>1,171 breast

cancer incident

Table 6. (Ishitani, 2008)


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TITLE VARIABLES# of

PARTICIPANTS

TYPE OF

STUDY

YEARS of

CONDUCTION

RESULT/

FINDINGS

Dietary BetaCarotene, Vit

C And E

Intake AndBreast

Cancer Risk

In The

EuropeanProspective

Investigation

Into CancerAnd

Nutrition

((EPIC)

>Vit. Cintake

>Risk of

breast cancer

>345,995women

>Cohort

studyusing food

frequencyquestionnaire

>8.8 years

>Dietary intakeof beta-

carotene, vit. C

& E was notassociated with

breast cancer

risk

>7,502 breast

cancer incident

Table 8. (Nagel, 2009)

TITLE VARIABLES# of

PARTICIPANTS

TYPE OF

STUDY

YEARS of

CONDUCTION

RESULT/

FINDINGS

Multi-

Vitamin Use

And BreastCancer

Incidence In

A

ProspectiveCohort Of

Swedish

Women

>MultiVitamins--

Vit. C intake

>Risk of

breast cancer

>35, 329

women

>Cohort

studyusingquestionnaire

>9.5 years

>No significant

increase in risk

of breast cancerin women who

took specific

supplement

(Vit. C) thanthose who did

not take

>974 breastcancer incident

Table 7. (Larsson S. C., 2010)


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IX. REFERENCESChen Q., e. a. (2005). Pharmacologic Ascorbic Acid Concentrations Selectively Kill Cancer Cells: Action

As a Pro- Drug To Deliver Hydrogen Peroxide To Tossues. Proc Natl Acad Sci USA .

Cho, E. e. (2003, August). cebp. Retrieved February 15, 2012, from cebp.aacrjournals.org:

http://cebp.aacrjournal.org/content/12/8/713.full.pdf+html

Hunter, D. J. (1993). A prospective study of the intake of Vitamins C, E, and A and the risk of breast

canceer. The New England Journal of Medicine , 234-240.

Ishitani, K. e. (2008, March 15). A Prospective Study of Multivitamin Supplement Use and Risk of Breast

Cancer.American Journal of Epidemiology , 1197-1206.

Larsson, S. C. (2010). Multivitamin use and breast cancer incidence in a prospective cohort of Swedish

women. The American Journal of Clinical Nutrition , 1268-1272.

Mirkin, G. (2002). Vitamins Do Not Treat Breast Cancer. Retrieved January 6, 2012, from Breast Cancer

Research and Treatment: http://www.drmirkin.com/women/1581/html

Nagel, G. e. (2009, November 11). Dietary beta carotene, vitamin C and E intake and breast cancer risk in

the European Prospective Investigation into Cancer and Nutrition.Breast Cancer Research and Treatment,

753-765.

Padayatty J., e. a. (2006). Intravenously Administered Vitamin C As Cancer Therapy: Three Cases. CMAJ.

Rohan, T. e. (1993, January 4). Dietary fiber, vitamins A, C, and E, and the risk of breast cancer: a cohort

study. Cancer Causes Control .

S. Gandini, e. a. (2000).Meta-analysis of studies on breast cancer risk and diet: the role of fruit and

vegetable consumption and the intake of associated micronutrients. Retrieved January 6, 2012, from

European Journal of Cancer: http://www.medicine.ox.ac.uk/bandolier/booth/hliving/FVbreast.html

Verhoeven, D. (1997). Vitamins C and E, retinol, beta-carotene and dietary fibre in relation to breast cancer

risk: a prospective cohort study.British Journal of Cancer, 149-156.

Zhang, S. (1999). Dietary Carotenoids and Vitamins A, C, and E and Risk of Breast Cancer.Journal of the

National Cancer Institute , 547-556.

(n.d.). Retrieved November 25, 2011, from www.google.com:

http://www.who.int/mediacentre/factsheets/fs297/en/index.html

(n.d.). Retrieved November 25, 2011, from www.google.com: http://www.healthcommunities.com/breast-

cancer/overview-of-breast-cancer.shtml

(n.d.). Retrieved November 25, 2011, from www.wikipedia.com: http://www.imaginis.com/breast-

health/breast-cancer-statistics-on-incidence-survival-and-screening-2

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