癌症 z-bo 2020-09-18 326

　　Contagious cancer

　　Cancer is terrible, but at least it is not contagious. This is our previous understanding, but the latest research by the Howard Hughes Medical Institute and Columbia University confirms that cancer can also be contagious.

　　On the east coast of North America, soft-shelled clams die from a kind of leukemia, almost like a plague. Scientists have long suspected that a certain virus caused leukemia in healthy soft-shelled clams. They never thought that leukemia might be contagious. The team of Columbia University professor Michael Metzger confirmed that the soft-shelled clams Leukemia is contagious. If the blood cells of soft-shelled clams suffering from this leukemia are injected into healthy soft-shelled clams, some of them will unfortunately suffer from leukemia.

　　This leukemia is related to a self-replicating DNA sequence "Steamer". There are only 2-10 copies of Steamer in the normal soft-shell clam genome, and 150 to 300 copies in the soft-shell clam genome with leukemia. Such abnormal replication can easily destroy the original important genes of the body and even cause leukemia.

　　Soft-shelled clams are actually not the first animal to be miserably affected by infectious cancers. Previous studies have found that two types of cancer can be transmitted between animals, and both Tasmanian devil and dogs have been recruited.

　　Tasmanian devil lives in Tasmania, Australia. The fierce and capable Tasmanian devil often suffers from Facial Tumor Disease (DFTD). What's more frightening is that this cancer can be contagious.

　　In 2006, Australian scientists discovered that a normal Tasmanian devil has 14 chromosomes, while a Tasmanian devil with DFTD has only 13 chromosomes that are riddled with holes. This chromosomal abnormality is the same in all diseased Tasmanian devil, thus confirming that DFTD is infectious.

　　When the Tasmanian devil bites each other for food or mating rights, cancer cells will take the opportunity to enter the wound on the Tasman’s face and spread at an alarming rate, causing the Tasman’s face to ulcerate and block the airway, making it difficult to eat. Died in hunger. Since the first case of DFTD was discovered in 1996, the number of Tasmanian devil has dropped by 60%, so it was officially listed as an endangered animal in 2008.

　　Compared to the poor Tasmanian, the dog is relatively lucky. Although CTVT was proven to be contagious as early as 1871, it is relatively mild, can be effectively treated with drugs, and can even heal itself.

　　In 2014, a Cambridge University study came to a surprising conclusion that all CTVT originated from a dog. CTVT may have appeared as early as 11,000 years ago, when the ice age had just ended.

　　The number of victims among animals may still be increasing. However, as of now, it has not been found that cancer can be transmitted between humans.

　　For the human body, there are three main ways of metastasis of cancer cells: blood, lymph, and implantation. Leukemia of soft-shelled clams is probably also a kind of planting metastasis. Cancer cells are transmitted in seawater and float to other soft-shelled clams, causing them to become sick.

　　Dr. Li Wenbin, director of the Office of Oncology Department of Capital Medical University and director of the China Anti-Cancer Association, told Caijing: "The so-called'tumor infections' discovered now almost all refer to viral infections, not the spread of tumor cells themselves. For patients with liver cancer, if they pass the hepatitis B virus to others, others may gradually develop liver cancer, or they may develop cervical cancer after being infected with the HPV virus. These are all viral infections."

　　Cancer cells are almost never directly transmitted between humans, but there are some extreme cases. For example, experts from the American Cancer Institute confirmed that a 28-year-old mother in Japan had transmitted leukemia to her unborn daughter.

　　Professor Mel Greaves, who conducted this research, believes that the transmission of cancer from pregnant women to babies is “extremely rare”, and so far only 30 suspected cases have been found worldwide.

　　"In theory, human skin cancer is somewhat similar to Tasmanian DFTD. In the case of poor human immunity, small wounds on the skin surface may become a hidden risk of skin cancer. So for cancer prevention, Enhancing immunity is the most important thing. An important direction in the treatment of cancer is immunotherapy, which is also a world-recognized research direction." Li Wenbin emphasized.

　　If the Creator has a "Schindler's List", then humans will undoubtedly be listed in the top position, blessed by a powerful immune system, for a long time, humans will not need to fear the threat of infectious cancer. But soft-shelled clams and Tasmanian devil, these two animals that are facing extinction due to infectious cancer, are still reminding us that cancer is constantly evolving, and humans need to remain vigilant on the long march of evolution.