world cancer report - iarc

Certain Possible Uncertain
Age Androgens Body size
High fat diet Race Sexual activity
Family history Estrogens Vasectomy
The distribution of mortality rates is less
affected than incidence by the effects of
early diagnosis of asymptomatic cancers
(whether through screening, or by detection
of latent cancer in tissue removed during
prostatectomy operations). Mortality
rates are comparatively high in North
America, Northern and Western Europe,
Australia/New Zealand, parts of South
America (Brazil) and the Caribbean, and in
much of sub-Saharan Africa and low in
Asian populations, and in North Africa (Fig.
5.46). The difference in mortality between
China and the USA is 26-fold (while it is
almost 90-fold for incidence). Racially
based differences are evident within the
United States, where the black population
has the highest incidence (and mortality)
rates, those rates being some 35% higher
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Selenium Vitamin A
Vitamin E/D Calcium
Phyto-estrogens Lycopene
Table 5.8 Risk and protective (in italics) factors for prostate cancer.
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than in whites, who in turn have rates considerably
higher than populations of Asian
origin (Chinese, Japanese, Korean).
Etiology
Age is the strongest risk factor for prostate
cancer. Development of this malignancy is a
multi-step process associated with a long
natural history [2]. It can be inferred that
the initiation of preneoplastic lesions and
microscopic cancer is influenced by environmental
factors which, in turn, implies a
case for lifestyle causes and primary prevention.
Although many of the risk factors for adenocarcinoma
of the prostate (Table 5.8) are
weakly linked, the strong association of
race, familial and geographic patterns with
mortality directs attention to a significant
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role for genetic-environmental interactions
as determining patterns of disease. Dietary
patterns suggest that saturated fat is a significant
risk factor, while micronutrients
such as the vitamins A, E and D, selenium,
lycopene and calcium may exercise a protective
effect against cancer.
The role of hormones, especially androgens,
is obviously important, granted the impact
of orchidectomy (excision of the testes) on
progression. However, an endocrine basis
for carcinogenesis is still not well understood.
Genetic polymorphisms in the androgen
receptor may be more important than
any imbalance of hormones in the circulation.
Studies of body size, vasectomy, sexual
activity and cigarette smoking as risk factors
have produced inconclusive, equivocal
results.
A diet characteristic of Asian countries such
as Japan and China, essentially a low fat
intake with consequent low body weight,
with an intake of relatively high levels of
phyto-estrogens (Box: Phyto-estrogens,
p78) may provide the means of restraining
the growth and progression of prostate cancer.
A strategy for prevention would be to
increase the intake of phyto-estrogens,
essentially isoflavonoids, lignans and possibly
certain flavonoids [3]. The years of
potential life saved by preventive measures
for prostate cancer may be less than for
cancers occurring earlier in life, but the
number of men with the disease worldwide
adequately justifies a focus on this effort
(Screening for prostate cancer, p160).
Fig. 5.46 Trends in prostate cancer mortality. Although mortality rates increased generally in the last 30 years, in some places, e.g. the USA, mortality is now
falling. D.M. Parkin et al. (2001) Eur J Cancer, 37 Suppl.8: S4-66.
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Cancers of the male reproductive tract 209