Lettuce and colorectal cancer.

Colon cancer risk: Data about salad/lettuce was provided by a pooled analysis of 12 cohorts, but information about these dietary variables was not stratified (29). Though RRs for the highest 2 quartiles of consumption were lower than for the 2 lowest quartiles (RRs 0.89-0.90 vs 1.00, respectively), no association was found with colon cancer risk.
Rectal cancer risk: Data about the relation with rectal cancer risk was provided by 3 cohorts (6, 9). No associations were found. Colorectal cancer risk: Data from an article about 1 cohort was not stratified by cancer site (though information about colon cancer was used by the pooled analysis). No association was found (23).

Conclusion: No evidence was found for an association between lettuce and colon or rectal cancer.

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Prospective studies of lettuce and colorectal cancer risk:

Author

Cohort name

Subjects

Years of follow-up

Cases

End point

Consumption of

Relative Risk (RR)

Adjustments

29) Koushik A. (2007)

Pooled Analysis of 12 Cohort Studies.

713,783 subjects.

6-20 years

5,509

Colon cancer risk

Lettuce, salad

INCLUSION CRITERIA:

Publication of a diet and cancer association.
Diagnosis of at least 50 incident colorectal cancer cases.
Assessment of usual diet.
Conduct of a validation study of the dietary assessment method or a closely related instrument.

INCLUDED STUDIES (Follow-up years/No. of colon cancer cases).
In the analysis, an extended follow-up period for most of the studies was included:

The Adventist Health Study. (1976-1982/52 men, 67 women)
Singh PN, Fraser GE. Dietary risk factors for colon cancer in a low-risk population. Am J Epidemiol. 1998 Oct 15;148(8):761-74. Full text
The Alpha-Tocopherol Beta-Carotene Cancer Prevention Study. (1984-1999/187 men)
Pietinen P, Malila N, Virtanen M, Hartman TJ, Tangrea JA, Albanes D. Diet and risk of colorectal cancer in a cohort of Finnish men. Cancer Causes Control. 1999 Oct;10(5):387-96. Abstract
The Cancer Prevention Study II Nutrition Cohort. (1992-1999/467 men, 349 women)
McCullough ML, Robertson AS, Chao A, Jacobs EJ, Stampfer MJ, Jacobs DR. A prospective study of whole grains, fruits, vegetables, and colon cancer risk. Cancer Causes Control. 2003 Dec;14(10):959-70. Abstract
The Health Professionals Follow-up Study. (1986-2000/456 men)
Michels KB, Edward Giovannucci, Joshipura KJ, Rosner BA, Stampfer MJ, Fuchs CS. Prospective study of fruit and vegetable consumption and incidence of colon and rectal cancers. J Natl Cancer Inst. 2000 Nov 1;92(21):1740-52. Full text
The Netherlands Cohort Study. (1986-1993/393 men, 353 women)
Voorrips LE, Goldbohm RA, van Poppel G, Sturmans F, Hermus RJ, van den Brandt PA. Vegetable and fruit consumption and risks of colon and rectal cancer in a prospective cohort study: The Netherlands Cohort Study on diet and cancer. Am J Epidemiol. 2000 Dec 1;152(11):1081-92. Full text
The New York State Cohort. (1980-1987/335 men, 223 women)
Bandera EV, Freudenheim JL, Marshall JR, Zielezny M, Priore RL, Brasure J. Diet and alcohol consumption and lung cancer risk in the New York State Cohort (United States). Cancer Causes Control. 1997 Nov;8(6):828-40. Abstract
The Breast Cancer Detection Demonstration Project Follow-up Study. (1987-1999/349 women)
Flood A, Velie EM, Chaterjee N, Subar AF, Thompson FE, Lacey JV Jr. Fruit and vegetable intakes and the risk of colorectal cancer in the Breast Cancer Detection Demonstration Project follow-up cohort. Am J Clin Nutr. 2002 May;75(5):936-43. Full text
The Canadian National Breast Screening Study. (1980-2000/431 women)
Terry P, Jain M, Miller AB, Howe GR, Rohan TE. Dietary intake of folic acid and colorectal cancer risk in a cohort of women. Int J Cancer. 2002 Feb 20;97(6):864-7. Abstract
The Iowa Women's Health Study. (1986-2001/799 women)
Steinmetz KA, Kushi LH, Bostick RM, Folsom AR, Potter JD. Vegetables, and fruit colon cancer in the Iowa Women's Health Study. Am J Epidemiol. 1994 Jan 1;139(1):1-15. Abstract
The Nurses' Health Study B. (1986-2000/429 women)
Michels KB, Edward Giovannucci, Joshipura KJ, Rosner BA, Stampfer MJ, Fuchs CS. Prospective study of fruit and vegetable consumption and incidence of colon and rectal cancers. J Natl Cancer Inst. 2000 Nov 1;92(21):1740-52. Full text
The Swedish Mammography Cohort. (1987-2003/484 women)
Terry P, Giovannucci E, Michels KB, Bergkvist L, Hansen H, Holmberg L. Fruit, vegetables, dietary fiber, and risk of colorectal cancer. J Natl Cancer Inst. 2001 Apr 4;93(7):525-33. Full text
The Women's Health Study. (1993-2003/163 women)
Lin J, Zhang SM, Cook NR, Rexrode KM, Liu S, Manson JE. Dietary intakes of fruit, vegetables, and fiber, and risk of colorectal cancer in a prospective cohort of women (United States). Cancer Causes Control. 2005 Apr;16(3):225-33. Abstract

RELATIVE RISK:

RR = 0.90 (0.79-1.03; P = 0.13) for the highest vs lowest quartile of consumption.

Amount specific data (servings):
0: RR = 1.
> 0 to < 1/wk: RR = 1.00 (0.89-1.13).
1/wk to < 0.5/day: RR = 0.89 (0.77-1.02).
≥ 0.5/day: RR = 0.90 (0.79-1.03).

One serving = 1 cup.

BMI; height; education; physical activity; family history of colorectal cancer; postmenopausal hormone use; oral contraceptive use; use of nonsteroidal anti-inflammatory drugs; multivitamin use; smoking habits (never/past/current + amount); red meat; total milk; alcohol; and total energy. Age in years and year of questionnaire return were included as stratification variables.

23) Lin J. (2005)

The Women's Health Study.

36,976 women aged > or = 45 years.
(USA)

223?

Colorectal cancer risk

Iceberg lettuce,
Romaine lettuce,
Head lettuce, or
Leaf lettuce.

Intakes of individual vegetable items were found not appreciably to be associated with colorectal cancer risk (data not shown).

age, randomized treatment assignment, BMI, family history of colorectal cancer, history of colon polyps, physical activity, smoking status, baseline aspirin use, red meat intake, alcohol consumption, total energy intake, menopausal status, baseline post-menopausal HT use, folate intake and multivitamin use. Glycemic load in the multivariate model did not change the overall results.

9) Voorrips LE. (2000)

The Netherlands Cohort Study.

62,573 women and 58,279 men aged 55-69.
(The Netherlands)

6.3
(1986-1992)

578? colon (312 men, 266 women), and 314? rectal (199 men, 115 women)

Colorectal cancer risk

Lettuce

**Stratified by cancer site**
Colon cancer	Rectal cancer
Men: RR = 1.43 Women: RR = 0.80	Men: RR = 0.95 Women: RR = 0.80

RRs are for an increment of 25 g/day.

Age, family history of colorectal cancer, alcohol, and items in the cooked vegetable group, raw vegetable group, and fruit group. Total energy intake, smoking, physical activity, and BMI were evaluated as potential confounders.

6) Michels KB. (2000)

The Nurses' Health Study
&
The Health Professionals' Follow-up Study.

88,764 women aged 34-59 and 47,325 men aged 40-75.
(USA)

Women: 16
(1980-1996).

Men: 10
(1986-1996)

1,181?
(937 colon cancer [368 men, 569 women], 244 rectal cancer [89 men, 155 women])

Colorectal cancer risk

head, iceberg, leaf, or romaine lettuce

Intake of individual vegetables that constitute the composite items was not appreciably associated with colon or rectal cancer risk in women or men (No data data shown).

age, family history of colorectal cancer, sigmoidoscopy, height, body mass index, pack-years of smoking, alcohol intake, physical activity, (women: menopausal status, postmenopausal hormone use,) aspirin use, vitamin supplement intake (ever use of multivitamins or vitamins A, C, or E), total caloric intake, and red meat consumption.

6) Giovannucci E. (1994)

The Health Professionals Follow-up Study.

47,949 men aged 40-75.
(USA)

1986-1992

205?

Colon cancer risk

Romaine or iceberg lettuce

Of all vegetable items examined individually, none were statistically significantly related to the risk of colon cancer (no data shown).

Age, energy.

Cancer & Diet. A systematic review.

Literature review.

Relating various aspects of our diet
to colorectal cancer risk & mortality.

Lettuce and colorectal cancer.

Cancer & Diet. A systematic review.

Literature review.

Relating various aspects of our dietto colorectal cancer risk & mortality.

Lettuce and colorectal cancer.

Relating various aspects of our diet
to colorectal cancer risk & mortality.