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pre-carcinogen
pre-carcinogen n. 
/(ˌ)priːˈkɑːsn̩ədʒ(ə)n/, /ˌpriːkɑːˈsɪnədʒ(ə)n/, /ˌpriˈkɑrs(ə)nəˌdʒɛn/ a non-carcinogenic precursor of a carcinogen.
Brit. /(ˌ)priːˈkɑːs(ᵻ)nədʒ(ə)n/
, /(ˌ)priːˈkɑːs(ᵻ)nədʒ(ə)n//(ˌ)priːˈkɑːsn̩ədʒ(ə)n//ˌpriːkɑːˈsɪnədʒ(ə)n/U.S. /ˌpriˌkɑrˈsɪnədʒən/
, /ˌpriˌkɑrˈsɪnədʒən//ˌpriˈkɑrs(ə)nəˌdʒɛn/ΚΠ
1948 I. Berenblum in Unio Internat. Contra Cancrum Acta 6 18/1 Support for the theory would be derived from the discovery of a pure precarcinogen (i.e. one which is not itself carcinogenic, but which, when followed by croton oil treatment, would lead to the development of tumours).
1990 Mutagenesis 5 623/2 Myrcene may exert an antimutagenic effect by inhibiting certain forms of cytochrome P-450 enzymes required for the activation of pre-mutagens and pre-carcinogens.
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