I did not find a lot of medical information on smell and cervical cancer. But I did find a number of forums where women talked about noticing a smell before their diagnosis. Since abnormal discharge can be a symptom of cervical cancer, it would certainly make sense that it could be accompanied by a unpleasant smell.
But, of course, there are so many reasons for bad-smelling vaginal discharge, I don't think anyone should panic that they have cervical cancer if they development abnormally smelling discharge. But, of course, abnormal vaginal discharge is always a good reason to check in with your doctor. That's MHO, and I am not a doctor.