Carrots and lung cancer.

Lung cancer risk: Data about lung cancer risk was provided by a pooled analysis of 7 studies, and an additional 6 cohorts including a total of 10,425 cases.
A significant protective effect of high vs low consumption was found only in one small cohort (8), and in the male part of one cohort of very large size (29). All other RRs were ≤ 1.

Inclusion of intermediate levels of consumption:
The figure below included RRs from all cohorts in which any (non)significant association was found at any level of consumption. Significant protective effects were found at intermediate levels of consumption: A significant protective effect was found at the level of consumption of > 0 to < 1 serving/wk in a pooled analysis of 7 cohorts (24), and in the male part of a cohort of very large size at 2 levels of consumption (median 0.53 serving/wk, and 3.68 servings/wk [29]). This analysis included 6,985 cases (67% of all cases):

RRs for carrots in servings/week.

Lung cancer mortality: Data about lung cancer mortality was provided by 1 cohort (9). A nonsignificant protective effect was found.

Conclusion: No evidence was found for a protective effect of high vs low consumption of carrots. Significant protective effects against lung cancer risk were found at intermediate levels of consumption in a pooled analysis of 7 cohorts, and the male part of another cohort (67% of all cases). No (non)significantly increased risks of intermediate levels of consumption were found in any cohort. Carrots possibly protect against lung cancer risk at an intermediate level of carrot consumption (0.5 to < 1 serving/week).

Men. Stratified by smoking status:

Never smokers
(141? cases)

Former smokers
(2,110? cases)

Current smokers
(1,583? cases)

RR = 0.76 (0.46-1.27; P = 0.78) for the highest vs lowest quintile of consumption.

RR = 0.77 (0.67-0.89; P = 0.0009) for the highest vs lowest quintile of consumption.

RR = 1.02 (0.86-1.21; P = 0.81) for the highest vs lowest quintile of consumption.

Women. Stratified by smoking status:

Never smokers
(170? cases)

Former smokers
(835? cases)

Current smokers
(1,196? cases)

RR = 0.76 (0.45-1.28; P = 0.13) for the highest vs lowest quintile of consumption.

RR = 0.90 (0.72-1.12; P = 0.64) for the highest vs lowest quintile of consumption.

RR = 0.99 (0.81-1.21; P = 0.80) for the highest vs lowest quintile of consumption.

Intervention arm (daily combination of 30 mg of beta carotene and 25,000 IU of retinyl palmitate):
(n = 7072)

Placebo arm:
(n = 7048)

RR = 0.88 (0.63-1.23; P = 0.77) for the highest vs lowest quintile of consumption.

Amount specific data (servings/week):
≤ 0.1: RR = 1.
0.2-0.5: RR = 0.84 (0.63-1.11).
0.6-0.9: RR = 0.88 (0.66-1.19).
1.0-2.0: RR = 1.01 (0.74-1.37).
≥ 2.1: RR = 0.88 (0.63-1.23).

RR = 0.80 (0.54-1.18; P = 0.27) for the highest vs lowest quintile of consumption.

Amount specific data (servings/week):
≤ 0.1: RR = 1.
0.2-0.5: RR = 1.08 (0.79-1.47).
0.6-0.9: RR = 1.12 (0.80-1.55).
1.0-2.0: RR = 0.96 (0.66-1.39).
≥ 2.1: RR = 0.80 (0.54-1.18).

Cooked carrots:

Raw carrots:

RR = 0.9 (0.4-2.0; P = 0.36) for the highest vs lowest quintile of consumption.

Amount specific data:
< 1 x/month: RR = 1.
1 x/month: RR = 0.8 (0.6-1.0).
2-3 x/month: RR = 1.0 (0.8-1.2).
1 x/wk: RR = 1.1 (0.8-1.5).
: RR = 0.9 (0.4-2.0).

RR = 1.0 (0.8-1.4; No P value) per 25 g/day increment.

Stratified by histological type:

Adenocarcinoma
(45 cases)

Small cell carcinoma
(37 cases)

Squamous cell carcinoma
(25 cases)

Large cell carcinoma
(12 cases)

OR = 0.60 (0.28-1.29; P = 0.18) for the highest vs lowest tertile of consumption.

Amount specific data (servings/wk):
≤ 0.5: OR = 1.
1.0: OR = 0.55 (0.27-1.14).
≥ 3.0: OR = 0.60 (0.28-1.29).

OR = 0.74 (0.31-1.75; P = 0.49) for the highest vs lowest tertile of consumption.

Amount specific data (servings/wk):
≤ 0.5: OR = 1.
1.0: OR = 0.90 (0.42-1.96).
≥ 3.0: OR = 0.74 (0.31-1.75).

OR = 0.72 (0.28-1.84; P = 0.49) for the highest vs lowest tertile of consumption.

Amount specific data (servings/wk):
≤ 0.5: OR = 1.
1.0: OR = 0.31 (0.10-1.00).
≥ 3.0: OR = 0.72 (0.28-1.84).

OR = 0.40 (0.10-1.57; P = 0.19) for the highest vs lowest tertile of consumption.

Amount specific data (servings/wk):
≤ 0.5: OR = 1.
1.0: OR = 0.12 (0.01-0.97).
≥ 3.0: OR = 0.40 (0.10-1.57).

Stratified by smoking status:

Current smokers
(81 cases)

Exsmokers
(38 cases)

Never smokers
(19 cases)

OR = 0.57 (0.30-1.09; P = 0.09) for the highest vs lowest tertile of consumption.

Amount specific data (servings/wk):
≤ 0.5: OR = 1.
1.0: OR = 0.69 (0.39-1.22).
≥ 3.0: OR = 0.57 (0.30-1.09).

OR = 0.82 (0.37-1.83; P = 0.63) for the highest vs lowest tertile of consumption.

Amount specific data (servings/wk):
≤ 0.5: OR = 1.
1.0: OR = 0.53 (0.21-1.30).
≥ 3.0: OR = 0.82 (0.37-1.83).

OR = 1.19 (0.43-3.28; P = 0.75) for the highest vs lowest tertile of consumption.

Amount specific data (servings/wk):
≤ 0.5: OR = 1.
1.0: OR = 0.22 (0.05-1.08).
≥ 3.0: OR = 1.19 (0.43-3.28).

Primary tumours:

Squamous and small-cell carcinomas:

Relative odds = 0.75 (P = 0.14) for the highest vs lowest quintile of consumption (> 14 vs < 1 times/month).

Relative odds = 0.64 (P = 0.08) for the highest vs lowest quintile of consumption (> 14 vs < 1 times/month).

**Prospective studies of carrots and lung cancer mortality:**
Author	Cohort name	Subjects	Years of follow-up	Cases	End point	Consumption of	Relative Risk (RR)	Adjustments
9) Chow WH (1992)	The Lutheran Brotherhood Study	17,633 white men aged 35 or over. (USA)	20 (1966-1986)	219	lung cancer mortality	Carrots	Linked to a lower risk of lung cancer death, but nonsignificant (no data shown).	Age, industry/occupation, and smoking status.

Prospective studies of carrots and lung cancer mortality:

Author

Cohort name

Subjects

Years of follow-up

Cases

End point

Consumption of

Relative Risk (RR)

Adjustments

9) Chow WH (1992)

The Lutheran Brotherhood Study

17,633 white men aged 35 or over.
(USA)

20
(1966-1986)

219

lung cancer mortality

Carrots

Linked to a lower risk of lung cancer death, but nonsignificant (no data shown).

Age, industry/occupation, and smoking status.

Cancer & Diet. A systematic review.

Literature review.

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

Carrots and lung cancer.

Cancer & Diet. A systematic review.

Literature review.

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

Carrots and lung cancer.

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