Even if researchers are making enormous efforts of making cancer causes review in order to clarify certain causes of cancer, they still remain unclear. However, there are some factors that are definitely increasing a risk for cancer, such as tobacco and ionizing radiation. Their negative influence on human overall health and, particularly, the capacity to increase the risk for cancer development have been proved by numerous studies and researches. Other supposed cancer causes still need additional research.
Now let's make a brief cancer causes review, according to the latest data. To fulfill the basic cancer causes review we can classify them in several categories: environment, diet, heredity, viruses, radiation, and so on. One of the controversial factors that suppose to cause cancer is heredity. The cancer causes review includes some facts that we know about heredity.
Researchers from the Karoliska Institute in Sweden effectuated an interesting study in identical twins. The main purpose of the research was to separate environmental factors from genetic factors in cancer development. The study was based on the principal that identical twins share the same genes. So, if cancer would have a hereditary origin, and one of the twins would have cancer, the second twin should develop cancer at the same age and in the same part of the body. The results of the study showed that if one of the twins has cancer the chances of the other to develop the same type of cancer were less than 15%.
So, environmental factors remain decisive in cancer development. However, there are certain types of cancer that are recognized to have a hereditary component. They include mutations in BRCA1 and BRCA2 genes that are associated with a high risk of breast and ovarian cancer; Turcot syndrome (brain tumor and colon polypose); Li-Fraumeni syndrome; retinoblastoma in children and others.
Genetic mutations seem to be responsible for only 5-10% of all the cancers. And it is important to understand that if someone inherits the gene that increases the risk for a certain type of cancer does not mean that he/she inherits cancer itself. Genetic factor only creates a predisposition to cancer development. That means that only a high risk of cancer development can be inherited, but not the cancer.
Cancer is a multi-factorial disease, which means that it is caused by a combination of several factors. That is why, theoretically, a person with an inherited high cancer risk can avoid other potential factors that may trigger the disease and may avoid cancer. Environment and diet have a greater impact on cancer development. Some of these factors include tobacco smoking, infections, unbalanced alimentation, obesity, sun exposure and others. It has been proved that a healthy alimentation, including a sufficient amount of fruit and vegetable, with a reduced caloric value and poor in saturated fats constitutes an efficient prophylaxis for certain types of cancer, such as lung and colon cancers.
An interesting migration study has shown that geographic location and lifestyle play an important role in cancer development. For example, people who migrated from Japan to the USA have predominantly developed colon cancer, which has a high rate in the US and a low rate in Japan. Making the cancer causes review we can affirm that environment and diet have a greater impact in cancer development comparing to hereditary factors.