Table 2.
Doll and Peto's tabulation of proportions of all cancer deaths attributable to various different risk factors in the USA in 1978 (Doll and Peto, 1981).
| Factor or class of factors | % of all cancer deaths | Scope for updates | |
|---|---|---|---|
| Best estimate | Acceptable range | ||
| Tobacco | 30a | 25–40 | Going down in more developed and up in less developed countries |
| Alcohol | 3 | 2–4 | Much higher in some countries; it did not include breast cancer |
| Diet | 35 | 10–70 | Still uncertain but probably lower, even including overweight and obesity, physical activity, salt, and low fruit and vegetable intake |
| Food additives | <1 | −5 to 2b | |
| Reproductive and sexual behaviours | 7 | 1–13 | Increasingly important in many less developed countries in which childbearing is being delayed and family size reduced. Sexual behaviour should be partly moved to Infection |
| Occupation | 4 | 2–8 | |
| Pollution | 2 | <1–5 | |
| Industrial products | <1 | <1–2 | |
| Medicines and medical procedures | 1 | 0.5–3 | On the rise due to increases in use of ionising radiation in imaging and cancer treatment and of drugs with immunosuppressive and carcinogenic effects |
| Geophysical factorsc | 3 | 2–4 | It did not include radon |
| Infection | 10? | 1–? | Only HBV and EBV were well‐established carcinogens. Very different by countryd |
| Unknown | ? | ? | |
a
60% in current smokers (Peto, 2001).
b
Allowing for a possibly protective effect of antioxidants and other preservatives.
c
About 1%, not 3%, could reasonably be described as “avoidable” (see text). Geophysical factors also cause a much greater proportion of non‐fatal cancers (up to 30% of all cancers, depending on ethnic mix and latitude) because of the importance of UV light in causing the relatively non‐fatal basal cell and squamous cell carcinomas of sunlight‐exposed skin.
d
See Table 3 for current best estimates.