Enhanced formation of benzo(a)pyrene:DNA adducts in monocytes of patients with a presumed predisposition to lung cancer.

Blood monocytes from 45 selected patients with lung cancer and 30 healthy controls were incubated with [G-3H]-benzo(a)pyrene for 30 h, and the formation of covalently bound DNA adducts was determined. The lung cancer patients were either relatively young (below 46 yr), nonsmokers, or had at least one first degree relative with lung cancer. Therefore, they might be considered cancer prone. The DNA adducts were significantly elevated in 22 patients with early age cancer (4.34 fmol/micrograms of DNA; P less than 0.04). In 12 familial cases, the slight elevation (2.77 fmol/micrograms of DNA) was not statistically significant in comparison to healthy controls. Benzo(a)pyrene:DNA adduct levels did not differ significantly between smokers and nonsmokers. Eight of 9 lung cancer patients with DNA adducts equal or above 4.5 fmol/micrograms of DNA but only 16 of 36 with adducts below this value had either oat cell or squamous cell cancer (P less than 0.05). The observed enhanced formation of covalent DNA adducts in blood monocytes exposed to a carcinogenic polycyclic hydrocarbon may be genetically determined and could play a role in the development of lung cancer at an early age.