Is vaginal discharge with a foul odor a common symptom of cervical cancer? Also what else could cause it?

Lots of causes. Cervical cancer may cause foul smelling discharge but there are far commoner causes, e.g., yeast infection, bacterial vaginosis and trichomonas etc. See this site for information and consult your doctor for a proper diagnosis and care. http://www.nlm.nih.gov/medlineplus/ency/article/003158.htm.