Malignant tumors are cancerous because they contain cells that are abnormal and uncontrolled. These cells are abnormal because they have changed from the original cell type and are growing and dividing uncontrollably, without regard for the body's natural boundaries. This uncontrolled growth of cells can interfere with the body's normal processes and can even spread to other parts of the body, a process known as metastasis.
Malignant tumors can be caused by genetic mutations that occur in the cells, which can cause them to have an increased rate of growth and division. Environmental factors, such as exposure to radiation or certain chemicals, can also cause these mutations and lead to the formation of malignant tumors. Some cancers, such as breast cancer, are caused by a combination of genetic mutations and environmental factors.
Malignant tumors are different from benign tumors in that they are more aggressive, can spread to other parts of the body, and are more likely to recur. Benign tumors, on the other hand, are not cancerous, meaning they do not contain abnormal cells and do not spread to other parts of the body. In addition, benign tumors tend to grow more slowly and can often be successfully treated.
Overall, malignant tumors are cancerous because they contain abnormal cells that have uncontrolled growth and division, which can lead to metastasis. These cells can be caused by genetic mutations or environmental factors, and they can be more aggressive and difficult to treat than benign tumors.