Cancer is a spreading unchecked and improper multiplication of cells in an animal. There are a lot of varieties, and some are more lethal than others (although all can be lethal, especially without treatment). Something like one in four cases of cancer are linked to smoking tobacco. Methods of treatment are increasingly effective, but most essentially boil down to trying to kill the cancer before the treatment kills the person with the cancer, so the treatments are also potentially lethal.
In wealthier parts of the world, some forms of cancer are almost always survivable with treatment, including breast cancer and prostate cancer. In less wealthy parts of the world, cancers in general are significantly more likely to result in the affected person's death.
Because there are a variety of cancers, a wide range of prognoses depending on the variety and the individual situation, and because it is depressing and scary to read about, we don't really want to write a particularly in-depth or useful article. If you are in a situation involving cancer or suspect that you might be, you should absolutely be talking to a doctor instead of reading this website. Also, we feel confident in saying that you should not smoke tobacco.
Cancer is very dangerous.
