Cancer-causing factors are very complicated, and mental factors play an important role in the occurrence and development of cancer. Modern medical science has found that cancer is more likely to occur in people who are frustrated and under long-term emotional stress such as mental depression, anxiety, depression, bitterness, fear and sadness. Psychological factors do not directly cause cancer, but they tend to influence and reduce the immunity of the body with a chronic and continuous stimulation, increasing the incidence of cancer. Personality and disease Some scholars from the University of London, after more than 20 years of research, found that human personality can be divided into 4 types, and there are some relationships between personality and disease as follows. Type 1 personality: dependent, prone to a sense of despair and powerlessness when worrying, a type prone to cancer; Type 2 personality: less dependent, prone to anger and excitement when worrying, a type prone to ischemic heart disease; Type 3 personality: has both sides of Type 1 and 2. Type 4 personality: has self-discipline, good stress ability, and is a normal type. The causes of death from disease in these people mentioned above are also clearly in line with such a pattern. Therefore, some people call the type 1 personality “cancer personality”, “tumor personality”, and others call it “C-type behavior”. Cancer personality, generally known as C personality, refers to the personality traits that predispose individuals to cancer. According to relevant statistics, cancer patients generally have certain specific personality traits, and those with these personalities are more prone to cancer than others, hence the term “cancer personality”. Most of the cancer patients have experienced major life changes such as death of relatives, loss of love, divorce, unemployment, demotion or natural or man-made disasters before they got sick, and these major life events combined with negative emotions are very likely to form “cancer personality”. These people are introverted, apparently submissive and uncomplaining, but inwardly they are discontented and struggling with pain, and have a history of mental trauma; they are depressed and sulking, but they do not like to vent their anger; a very small thing in life can make them anxious and nervous, and they are always in a state of tension; on the surface, they always sacrifice themselves for the sake of others, but inwardly they are extremely reluctant; when they encounter difficulties, they do not try their best to overcome them at first, but drag them out until they are in a difficult situation. In the end, they have to do the fight of the beast; they are afraid of competition and escape from reality, trying to achieve a false psychological balance by means of appeasement, etc. The human nervous system, endocrine system and immune system share a set of signals. Once disturbed by “cancer personality”, it will lead to disorder of neuroendocrine activities and dysfunction of organs, and lower immune ability and weaken immune surveillance function of the body, which will affect the surveillance role of immune system in identifying and destroying cancer cells and lead to transformation and mutation of cancer cells.