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Observational epidemiological surveys (WG 3) page 43
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1-3-3 The CARET study
The relative risk for cancer incidence in the treated group was 1.3 (1.0-1.6), and the mortality
for the whole cohort was 1.5 (1.1-2.0). A subsequent analysis showed that the risk was
concentrated in the asbestos exposed group (1.8; CI:1.2-1.8), current smokers group (1.4; CI:
1.0-1.9), and former smokers exposed to asbestos (2.3; CI:1.2-4.7), whereas former smokers
at base-line not exposed to asbestos showed no excess risk.
1-3-4 The Physician Health Study
There were virtually no differences in the overall incidence of malignant neoplasms (0.98;
CI:0.91-1.06), or in the overall mortality. There were also no difference according to the type
of cancer or tobacco use. It is to be noted that there was a lower OR for prostate cancer in
cases supplemented with β-carotene who displayed a low level of lycopene than in the
placebo group with the same lycopene plasma concentration (Gann et al., 1999).
1-3-5.The Women’s Health Study
There were virtually no differences in the overall incidence of malignant neoplasms (1.03; CI:
0.82-1.28), or in the overall mortality (1.11; CI: 0.67-1.85). There were too few smokers to
conduct meaningful analysis for site specific cancers but the OR was non significant for all-
cancer sites in smokers (Lee et al., 1999)
1-3-6 The Polyp Prevention Study
There was no evidence that either β-carotene (1.01; CI:0.85-1.2) or vitamins C and E (1.08;
CI:0.91-1.29) reduced the incidence of adenomas. For one or more adenomas developed in
the left colorectum, the OR was 1.16 (0.88-1.52) for β-carotene supplementation and 0.88
(0.67-1.15) for vitamins C and E supplementation.
1-3-7 The Australian Polyp Prevention Study
There was no evidence of a reduction in incidence in the group receiving β-carotene (1.3;
CI:0.8-2.2). In the supplemented group the adenomas tended to be larger than 1cm, but this
increase in risk was also not significant.
1-3-8 The Skin Prevention Study
There was no effect of β-carotene supplementation on the development of new skin cancer in
any subgroup (sex, age, smoking, skin type, number of previous skin cancers). The relative
risk for all deaths from cancers was 0.83 (0.54-1.3) in the treated group and the OR for skin
cancer was 1.4 (0.99-2.1) among the smokers