DMBA is most widely used for inducing breast cancer in female rats. However it takes much longer time to induce (more than 6 months) which may not be feasible always due to time concern. Moreover, mortality is high.
However, we noticed that SD rats are more susceptible to cancer induction than Wistar rats.
In my experience, NMU works better than the DMBA in view of incidence rate and tumor latency (2-3 months). Moreover the mortality is almost nil with NMU, single 50 mg/kg, i.p. injection when the rat is 30-35 days old.