Mutagens are not necessarily carcinogens, and vice versa. Sodium azide for example may be mutagenic (and highly toxic), but it has not been shown to be carcinogenic. Meanwhile, compounds which are not directly mutagenic but stimulate cell growth which can reduce the effectiveness of DNA repair and indirectly increase the chance of mutations, and therefore that of cancer. One example of this would be anabolic steroids, which stimulate growth of the prostate gland and increase the risk of prostate cancer among others. Other carcinogens may cause cancer through a variety of mechanisms without producing mutations, such as tumour promotion, immunosuppression that reduces the ability to fight cancer cells or pathogens that can cause cancer, disruption of the endocrine system (e.g. in breast cancer), tissue-specific toxicity, and inflammation (e.g. in colorectal cancer).