Personally, I think that cancer existed in ancient times, but in ancient times, it was difficult to distinguish visceral cancer from other diseases because of the lack of modern scientific medical equipment such as X-rays and endoscopes. For example, the symptoms of quite common lung cancer are very similar to those of infectious tuberculosis, such as hemoptysis and emaciation. Before the end of gastric cancer, the only symptom may be vomiting, or colorectal cancer will only be constipation. In fact, many diseases have very similar symptoms. Today's medicine is based on the suspicion of repeated use of instruments in clinical diagnosis. If there was no knowledge of the existence of cancer in ancient times, there would be no special records. However, cancers visible on the human body, such as breast cancer and skin cancer, have similar descriptions.
Of course, the average life expectancy of ancient people is not as long as that of modern people, and many cancers grow with age. In addition, there was no serious environmental and chemical pollution in ancient times, and the incidence of cancer may not be as high as in modern times.
Modern medicine has also proved that many cancers have genetic factors, so ancient cancers should exist, but they are not accurately recorded for various reasons.