OLIVE OILS AND HEALTH 176 Figure 14.5. Hypothesis on the influence of environmental factors on the natural history of cancer. a) Hypothesis on the natural development of cancer : normality : cancer (including an initiation period, a latency period at the end of which clinical manifestations would appear, and there could also be a extension period through metastases). A certain time before the onset of clinical manifestations, tumours can be detected by imaging techniques and tumour marker tests within population screening programmes. Depending on the tumour’s biological aggressiveness, this progression will be faster or slower: the greater the aggressiveness, the faster the development. b) Influence of diet : natural development of cancer without the influence of environmental factors. : acceleration of the clinical course of the disease by promoting factors, among which there could be a harmful diet. : slower progression due to the influence of factors that slow down its development (healthy diet). : very slow progression in a tumour with low biological aggressiveness; the person dies at an age equal to or greater than the population’s life expectancy from other causes, without the cancer having produced any clinical manifestations (latent cancer); in a cancer with high biological aggressiveness, the influence of environmental factors would not be as relevant. Design and Image: Eduard Escrich-Escriche a) } 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 AGE AGE INITIATION LATENCY PERIOD (clinical manifestations) LATENCY PERIOD (diagnosis by screening) early detection by screening EXTENSION (metastatic progression) CLINICAL SUBCLINICAL CLINICAL SUBCLINICAL OTHER CAUSES SCREENING I' b) -- -- ■■
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