When administered by intravenous injection, MeCCNU induced lung tumors in rats. Adjuvant treatment with the compound has been evaluated in 3,633 patients with gastrointestinal cancer treated in nine randomized trials. Cumulative risk was not affected by concomitant radiotherapy or immunotherapy. A subsequent report described a strong dose-response relationship, giving a relative risk of almost fortyfold among patients who had received the highest dose. It is very slightly soluble in water, soluble in absolute ethanol, lipids, and nonpolar, organic solvents.
Conditions contributing to instability are acid, alkali and elevated temperatures.
MeCCNU is likely to be inactivated under conditions of fire. Hazardous decomposition products under conditions of fire are likely to include hydrochloric acid and nitrogen oxides. The same products are probably formed from MeCCNU and may also be decomposition products on ignition. MeCCNU is an experimental tumorigen.