It is recognised that some cancers can be prevented. Most mouth cancers can be prevented by not chewing tobacco  and most lung and throat cancers can be prevented by not smoking. Certain cancers are produced by chemicals used in industry. If workers are protected against contact with such occupational factors, some cancers can be prevented.
A well balanced diet with less fat and more green leafy vegetables, citrus fruits, milk etc.can protect people. Above all, eventhough not all cancers are preventable, many deaths due to cancer can be prevented by early detection and proper treatment. A knowledge of the warning signals of cancer helps one to get an early diagnosis and a successful treatment.