Abstract

OBJECTIVES:

• To review all prospective studies which provided data about total fruits or vegetables, their subgroups, and specific types of vegetables and fruits, in relationship with pancreatic cancer risk, disease progression and mortality/survival.
• To define the amount of consumption found to be related with the described effects on cancer.
• To define possible effect modification by confounders.

DATA SOURCE: The Pubmed database was searched (No start date - Sep 11, 2009) for relevant articles using the keywords "cancer, neoplasm, or neoplasms" combined with "vegetables, vegetable, fruit, or fruits" and a fair amount of other keywords. The exact search term is described in the methods.
Prospective studies published in the English language were included. Reference lists were searched for additional articles.
RESULTS: 25 articles were found which provided information about 21 different cohorts. Of these, 0 articles were excluded.
Results are described when any evidence for an association - as defined in the Methods - was found. In addition, data about total vegetables or fruits is described.

Total disease risk.

• Total vegetables: Data was provided by 7 cohorts, including 2,678 cases. No evidence was found for an association between total vegetables and pancreatic cancer risk (RR = 0.93).
• Total fruit: Data was provided by 9 cohorts, including 2,949 cases. No evidence was found for an association between total fruits and pancreatic cancer risk (RR = 1.03).

Advanced stage/metastatic disease risk or disease progression.
No data was found.
Mortality risk.

• Total vegetables: Data was provided by 3 cohorts, including 3,629 cases. No evidence was found for an association between total vegetables and pancreatic cancer mortality (RR = 0.89).
• Total fruit: Data was provided by 5 cohorts, including 510 cases. No evidence was found for an association between total fruits and pancreatic cancer mortality (RR = 0.76).

CONCLUSION: No evidence was found for an association between either total vegetables, or total fruits, and both pancreatic cancer risk or pancreatic cancer death. In addition, no evidence was found for an association between any vegetable/fruit subgroup-, or specific item and any cancer end point.
PERSPECTIVE: Very few significant associations were found by any article with any dietary variable. Almost all cohorts of very large size provided information about the relation between total vegetables or total fruits and pancreatic cancer risk (The NIH-AARP Diet and Health Study; The EPIC Study; The Multiethnic Cohort Study), so it is not to be expected that this evidence will change in the near future. No research was done about vegetable/fruit consumption after diagnosis of pancreatic cancer, so the possibility of an association with cancer death can not be excluded.

Total vegetables and pancreatic cancer.

Pancreatic cancer risk: Data about total vegetables was provided by 7 cohorts, including a total of 2,678 cases.
No (non)significant associations were found. The average RR = 0.93.

Inclusion of intermediate levels of consumption:
Data from one cohort (16) could not be used in the following table, because RRs were presented in g/1000 kcal/d. Since men and women consume different amounts of calories, no translation can be made to g/day.
(Non)significant effects at any level of consumption were restricted to findings from one cohort (George SM [17]). A significant protective effect was found at the level of consumption of 243-320 g/day among women. Noticeable is the fact that no RR was above 1 at the approximate level of recommended daily intakes: 193-262 g/day (2.5-3.4 servings/day).

Pancreatic cancer mortality: Data about total vegetables was provided by 3 cohorts, including a total of 3,629 cases.
A nonsignificant protective effect was found in one cohort, among men (5). No other associations were found. The average RR = 0.89 (excluding incomplete data from Zhang W [3]).

Conclusion: No significant association was found in any cohort. No evidence was found for an association between total vegetables and pancreatic cancer risk, or pancreatic cancer death.

Total fruit and pancreatic cancer.

Pancreatic cancer risk: Data about total fruit was provided by 9 cohorts, including a total of 2,949 cases.
A significantly increased risk was found in one cohort (16), but a significant protective effect was found in another cohort, among men (17). No other (non)significant associations were found. The average RR = 1.03 (excluding incomplete data from Michaud DS [12]).

Inclusion of intermediate levels of consumption:
Data from one cohort (16) could not be used in the following table, because RRs were presented in g/1000 kcal/d. Since men and women consume different amounts of calories, no translation can be made to g/day.
(Non)significant effects at any level of consumption were restricted to findings from one cohort (George SM [17]). A significant protective effect was found at the level of consumption of > 636 g/day, among men.

Pancreatic cancer mortality: Data about total fruit was provided by 5 cohorts, including a total of 510 cases.
A significant protective effect was found in one cohort among men (Lin Y [15]). No other (non)significant associations were found, but all RR's were < 1. The average RR = 0.76.

Conclusion: Few associations were found. No evidence was found for an association between total fruits and pancreatic cancer risk, or pancreatic cancer death. But the RR for pancreatic cancer death was well below 1.