Many factors are involved in cancer, so it’s not always easy to tell why cancer develops, or what causes it—but we know for sure that the following six factors do not play a role in the development of cancer.

Other People: Cancer is not a contagious disease, and it does not pass from one person to another except for in extremely rare circumstances. Certain genes passed by parents, such as BRCA1 and BRCA2, can heighten a person’s risk of developing cancer—keep in mind, however, that this is different from a person inheriting cancer itself.

Certain sexually transmitted diseases can lead to cancer; but again, this is different from cancer being passed from person to person. HPV, for example, causes cervical, vaginal, vulvar, anal, penile, and oropharyngeal cancers. Practicing safe sex is important for avoiding or addressing these diseases if they arise.

Deodorant: A common myth is that by blocking sweat glands in the armpits (particularly in those who shave their underarms), antiperspirants allow toxic compounds to accumulate in the underarm lymph nodes near the breasts, prompting cancer to develop. However, research has found no conclusive evidence to connect deodorant or antiperspirant use and breast cancer.

Tumor Biopsy: One myth suggests that a tumor biopsy, or another surgical procedure, will allow cancer cells to escape and spread within the body. But medical evidence supports the fact that this is unlikely, as most cancer cells that get displaced into the surrounding environment will likely be cleared by immune cells. Research also shows that patients who have biopsy procedures to confirm their respective diagnoses and determine the cancer’s stage had a better outcome and longer survival than patients who did not have a biopsy.

Your Personality: It was once believed that people with certain personality traits were particularly susceptible to cancer, such as neurotic people and introverts. Research has debunked this myth. However, certain traits are associated with behaviors that can raise or lower cancer risk. Highly health-conscious people are unlikely to engage in activities—like smoking, overeating, or basking in the sun too long—associated with cancer. People who pay less attention to diet and exercise may put themselves at higher risk for the disease.

Massages and Lymphoma: One myth suggests that full body massages can spread lymphoma because the therapy stimulates your lymphatic system—tissues and organs (including the thymus, spleen, bone marrow, lymphatics and lymph nodes) that produce white blood cells to fight infections and various diseases. The speculation is that mechanisms of massage can increase blood circulation and lymphatic flow. But there is absolutely no evidence that lymphoma can be spread by massage.

Soy: Research indicates that eating soy products is safe for breast cancer survivors. We looked at data among many breast cancer survivors, both from the United States and from Asia, and what we’re looking to see is what soy intake is safe for breast cancer survivors. And what we found is that even who ate a large amount of soy they actually had either the similar or decreased risk of breast cancer recurrence compared to women who didn’t eat soy.