Cancer cells can invade other parts of the body, where they can settle and grow to form new tumors called secondary tumors, the original tumors are called primary tumor. The cells spreading through the blood vessel can move through the body.
The process of spreading cancer cells is called metastasis. Once the cancer has begun metastasis, the chances of cure often begin to fall, because it becomes difficult to treat a range of different diseases.
Cancer causes damage to living organisms in many ways. The size of the tumor can affect adjacent organs or compressing the blood vessels or the parts around it. Such a tumor in the pancreas can develop and impede the bile duct, resulting in jaundice. A brain tumor can press the key part of the brain causing memory loss, convulsion and a variety of serious health problems.
Cancer is also the cause of a number of other common problems such as loss of appetite and increase energy use and weight loss or changes in the coagulation system leading to deep vein thrombosis.
Why is it difficult to treat cancer
Cancer is one of the diseases treated most complexly. Biologically, the types of cancer are very different. For example, skin cancer is completely different from blood cancer called lymphoma, because there are many types of lymphoma.
Early surgery is considered the best method to remove carcinogenic tumor. But cancer can still grow back if there are any pathogenic cells overlooked. Cancer may also return if the cells are broken from the primary tumor and form micro secondary tumors in other places in the body before surgery to remove the primary tumor.
And because cancer cells are of the human body, many treatments to destroy cancer cells can destroy the healthy cells.
The achievements in cancer treatment
Scientists studying cancer gradually abandon determining the origin disease diagnosis by monitoring the abnormal position of the body, because some breast cancers may have many characteristics similar to ovarian cancer than other types of breast cancer.
Instead, the scientists are seeking to study deviations from inside the cancer cells, since a tumor may have 100,000 genetic mutations and they change over time. And when identifying mutations causing cancer, the scientists said they would choose the drug more likely to treat each individual tumor.
Besides, the treatment using molecular level is currently being developed. It will prevent the development of cancer by interfering with the process of genetic changes and special molecules related to the progress and the development of tumors.
Clinical trials using gene therapies are also being conducted. Experimental treatment process includes adding genetic material into human cells to fight or prevent cancer.