Neither. Cancer can be caused by the long-standing inflammation in tissues affected by certain viruses (i.e. Hpv, hcv) and bacteria (i.e. H.Pylori), but cancer itself is not an infectious organism. Learn more about cancer and bacteria here: http://en.Wikipedia.Org/wiki/cancer_bacteria learn more about cancer and viruses here: http://en.Wikipedia.Org/wiki/cancer_virus.
No, But. Cancer is not a infectious etiology ( bacterial or viral). It is uncontrolled cell growth that has escaped normal mechanisms of control. But the chance of normal cells becoming cancerous are sometimes increased because of an infectious process. For example, hpv virus can increase risk of cervical cancer in women and some head and neck cancers in both genders.