Can nicotine replacement lozenges still cause oral cancer?  

Unlikely. Nicotene is addictive but not likely the cause of cancer for those who smoke or chew. Further, it would be very difficult to determine if an ex-smoker who uses nicorete developed cancer because of the gum becuase we know natural tobacco products do... Nicotene is not a known carcinogen but there are many carcinogens in natural tobacco: http://tinyurl.Com/3h74dkv.
Nicotine and Cancer. The carcinogens are contained with the tobacco more so than the nicotine. Lab studies have suggested that the foxm1 gene is activated by nicotine in mouth cells which raises the possibility that nicotine could potentially increase the risk of mouth cancer. High levels of foxm1, a protein that activates other genes may be associated with cancer. The association needs more study and is not proven.
No . Although nicotine may not be good for you, it is other chemicals in tobacco that are carcinogenic. Far better to chew the gum!