There does seem to be some association between severe stress, combined with other physical and genetic factors , which may contribute to heart disease, ulcers, and other ailments. Scientists continue to study the relationship between the onset of these diseases and high levels of stress. This is a complex question, but so far, there is no scientific evidence that proves that stress can cause cancer. There is also no evidence that if you are upset about having cancer you can cause your cancer to spread faster, or that being upset will interfere with the effectiveness of your treatment. The myth that cancer is always painful is associated with people's fear of the disease.
Some cancers cause no physical pain at all.
Some patients who die from cancer may experience mild to severe pain. The good news, however, is that with recent advances in pain management, pain can be prevented or controlled. We can now reassure the vast majority of patients with extensive disease that they will remain comfortable. If patients suffer from severe pain, they or their families must be aggressive in seeking the consultation of a pain specialist. The other myth about pain is that it is an early symptom of cancer.