Part of the reason is that people in the past usually didn't live long enough to get a lot of cancer.
Is cancer an infectious thing? Like a bacterial infection In fact, cancer is completely endogenous, it is a problem of the body itself, and it is not contagious.
After all, cancer is your own body trying to kill you. It's suicide without permission.
Cancer cells are just like normal cells, except that they proliferate wildly. Because it is normal on the surface, the body sometimes can't detect cancer cells and won't trigger an inflammatory reaction like external factors.
In other words, most cancers are painless and invisible in the early stage. Only when the tumor grows to compress the nerves or form a mass do we realize that something is wrong.
Cancer is very different from other diseases, and its attacks are often endless. Beating cancer is almost always hard-won, and often costly, at the expense of the overall health of the victims.
Faced with the impact, it will retreat, regroup and wait for another opportunity in a stronger form. Even if it fails on the surface, it may leave "dormant" cells, which can be revived after many years of dormancy.
Most importantly, cancer cells are selfish. Under normal circumstances, after completing the task, human cells accept the instructions of other cells and die for health. Tumor cells don't do this, they just spread for their own benefit.
Cancer is not a disease, but more than 200 disease packages with different causes and different prognosis. 80% of cancers, also known as malignant tumors, are produced in epithelial cells, that is, cells that make up skin and organ membranes. For example, breast cancer does not grow randomly in the breast, and usually starts from the mammary duct. Only about 1% of cancers appear in connective tissue, which is called sarcoma.
Lifestyle is an important factor in determining people's cancer. Studies have calculated that more than half of the cases are caused by things that we can take measures to solve, mainly smoking, drinking and overeating.
Environmental contact is also an important source of cancer. Pollutants in air and water, such as formaldehyde, viruses and bacteria, can also cause cancer.
The treatment of cancer was also rough and painful in the past.
Surgery is the only possible treatment, but in the days before anesthesia was invented, surgery was as painful as cancer itself and almost fatal. It was not until the middle of19th century that the development of anesthesiology largely eliminated the pain and panic caused by surgery.
In the last century, the Curies discovered radioactive substance: radium. But at that time, people thought that radiation was completely beneficial, and many drugs were added with radioactive products in large doses. But sometimes, radiotherapy attempts can bring good results. So it is still a means of treating cancer until now.
In the field of cancer treatment, chemotherapy is the third pillar after surgery and radiotherapy.
Mustard gas was essentially a weapon used by the army to kill each other in World War I, but it was unexpectedly discovered that some derivatives of these chemicals might be useful for treating some cancers, so chemotherapy was born.
Cancer is rare among children. Of the140,000 cancer cases diagnosed every year in the world, only about 2% of the patients are under the age of 19.
The main cause of childhood cancer is acute lymphoblastic leukemia, which accounts for about 80% of leukemia cases. Fifty years ago, it was equivalent to a death sentence. Drugs can relieve for a period of time, but the disease will come back soon, and the 5-year survival rate is less than 0. 1%. Today, the survival rate has reached 90%.
In any human body, this is a difficult thing, what's more, these bodies are still young and still developing. A large proportion of children's cancer deaths are directly caused by treatment rather than cancer.
The most obvious manifestation is the damage of hair cells, which makes the patient's hair fall off. More seriously, the treatment will also cause long-term damage to the heart and other organs.
Fertility of both sexes may be affected, which largely depends on the type and treatment of cancer. At present, in the United States, the number of people who died of cancer in the past 30 years has decreased by 2.4 million.