My grandmother recently passed away from cancer after it jumped from bladder to stomach. If it can spread throughout a body, why not person to person?
In: Biology
Cancer is just uncontrolled cell growth in a person’s body. If a cancer cell from somebody else’s body made its way into your body, your immune system would attack it like any other foreign particle.
if you transplanted an organ with cancerous cells, or even took cancerous stem cells into another person, it will proliferate. Some cancer in dogs is contagious.
Cancer is not a virus, amoeba or bacterial infection. They are your own cells with mutations that go unchecked as they split/reproduce
Cancer cells are normal body cells that have, for lack of a better term, “gone rogue”. They are cells that just keep growing (making tumors) and don’t listen when other cells tell them to stop. It’s difficult to fight because scientists have to find a way to only kill your misbehaving cells, without hurting your healthy ones. To your immune system, your cancer cells are just normal cells.
It spreads around the body mainly by having cells fall into the bloodstream and ride around until they anchor somewhere else.
The reason cancer cells don’t spread to other people is that they aren’t protected in other bodies. For example, if one of your grandmother’s cancerous cells had somehow gotten into your body, your immune system would recognize it as an invader and kill it immediately.
Does that make sense?
Cancer is not contagious in humans, plain and simple. If you really wanna learn something crazy, look up the laughing death. Yes, the laughing death. I did a report on it for first aid class, it’s totally not what anyone expects a disease to be. And it’s origins are pretty dark too.
Technically, it is contagious. It’s just extremely difficult to transmit. Most of the diseases that we encounter are contagious via being airborne, or in particles that rest on surfaces, or through direct skin-to-skin contact, or through bodily fluids. Cancer can’t be transmitted that way for two reasons: 1) it consists of human cells, which die very quickly outside the body. To keep the cells alive long enough to get into another person’s body is difficult. And 2) the immune system immediately recognizes that they are foreign and attacks and kills the cells. They don’t do this when the cancer originates in one’s own body because cancer is made up of your own cells and your body can have trouble recognizing them as foreign and dangerous. But it doesn’t have a problem recognizing other people’s cells, cancerous or not, as foreign and dangerous.
So the only way we’ve seen cancer be contagious in humans is through directly implanting it into the body in a way that keeps the cancerous cells alive during this transfer, *and* where the person getting the cells has a compromised immune system, since with a healthy immune system, the cells will be killed. Examples are: people who have had organ transplants. They won’t implant organs from a donor who has had cancer, but if they don’t know the person has cancer, then they’ll implant the organs. Then the person might develop cancer a year or a few years later, and the tumor cells will show an origin from the donor. People who have organ transplants take immunosuppressant drugs to prevent rejection of the foreign organ, but that also prevents the immune system from attacking the cancer.
Also, there’s the case of Henrietta Lacks. She had cervical cancer in 1951 and doctors took some samples of her cancer and then grew them in a dish. Her cancerous cells, referred to as HeLa cells, are now used in labs all around the world to be able to test things in a lab condition on human cells to see their effects. Usually, human cells may reproduce a few times in a lab petri dish, but then die off. But HeLa cells are almost unique in the world in their ability to keep growing and growing in a lab petri dish. 70 years later now and they’re still going strong. A test was done in which the HeLa cells were implanted in people to see if they would keep growing. Most test subjects’ bodies killed off the HeLa cells quickly. But when they tested the cells in the bodies of people who were already sick with their own cancer, there were one or two people in whom the cells continued to grow and divide and were not killed off. I believe they either then removed the cells, though I think one of the test subjects died of their own cancer before the HeLa cells were removed. These were people whose immune systems were already compromised, either because they had cancer, because of the cancer treatments, or they’d gotten cancer to begin with because their body’s immune system wasn’t too healthy beforehand.
There are also cancers that are caused by something infectious, and if a person transmits the infection to another person, then that other person could get cancer. So it’s not the cancer itself that is contagious, it’s the thing that causes the cancer that is contagious. The main examples of this are 1) Kaposi’s sarcoma. This is a cancer that is caused by a type of herpes virus that is transmissible via saliva. But the body’s defenses can almost always take care of it so a person doesn’t ever get cancer. So actual cancer is almost exclusively seen in people with immune system problems such as AIDS and organ transplant patients who take immunosuppresive drugs. 2) cervical/throat/anal cancer, caused by a type of human papilloma virus (HPV). This is a type of mainly genital warts that can be transmitted via sex. If penis-in-vagina sex, then a person can get cervical cancer or penile cancer (penile cancer extremely rare, but more common if uncircumcised and infected with this type of HPV). If transmitted via oral sex, then throat cancer is a possibility (see: Michael Douglas). If via anal sex, then anal cancer can result. Nowadays, there’s a vaccine against the type of HPV that causes this.
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