Page 14 - 72_03

VICTORIA LÓPEZ-RODAS Y COLS. AN. R. ACAD. NAC. FARM.

toxins ingested through shellfish consumption could contribute to
increase CRC incidence.

To support our hypothesis (a shellfish consumers have a
statistically significant higher risk to suffer colorectal cancer than a
no-shellfish consumers), we have performed an epidemiological
study to correlate dietary customs and tumour incidence. The data
of epidemiological study were obtained from the latest available
survey (1991) on habitual diet reflected into National Survey on
Nutrition and Food (Encuesta Nacional de Nutrición y Alimentación-
ENNA-91). The tumours incidence (rate of incidence in hospital
admissions in cases per 100,000 population) was obtained from the
Hospital Morbidity Survey (Encuesta de Morbilidad Hospitalaria) of
2003 (EMH - 03). The selected exposure variables were the
consumption of fresh bivalve molluscs (mussels, clams, cockles) as
the problem variable, and other food (bread, meat and meat
products, fish, fresh fruit, olive oil, milk and dairy products) as
control variables. The minimum of total admissions (CMBD) was
coded in accordance with the International Classification of Diseases.
We calculated regression, determination coefficients, confidence
interval and others using Epi-Info, version 6.04 (58).

The output on epidemiological study (Figure 3) has established a
statistically significant correlation (p < 0.001) between consumption
of molluscs and the incidence of colorectal cancer (coefficient
determination = 0.50). A correlation between the consumption
of molluscs and the total incidence of tumours was also observed
(Table 1). The consumption of other food was not associated with
colorectal cancer (with the exception of total meat consumption,
which is a known risk factor for this disease). An association between
shellfish consumption and meat consumption was also observed
(r2 = 0.39; p < 0.01). In the Spanish population, an increase of 7
times in shellfish consumption produces duplication in the risk ratio
of CRC (Table 2).

402