Final answer:
The statement is false. While there is a strong correlation between diet and certain types of cancer, causation has not been firmly established for all cases.
Step-by-step explanation:
The statement that virtually all etiological (causal) relationships between diet and cancer have been firmly established is:
False
While there is a strong correlation between diet and certain types of cancer, it is important to note that causation has not been firmly established for all cases. Epidemiological studies have linked a high fat intake with higher rates of breast, prostate, colon, and other cancers. However, randomized studies have not found a direct causal relationship between fat intake and tumor development or cancer risk reduction. Therefore, the evidence is currently unclear and it cannot be concluded that all etiological relationships between diet and cancer have been firmly established.