Looking at over 3000 skeletons dating from about 5300 BC to the 19th century AD, researchers have found much more evidence of tuberculosis, syphilis and leprosy than of cancer, but cancer is far more common today than those other diseases (How our ancestors avoided cancer). Cancer is linked to increased longevity, as cancer takes time to develop.
In Chinese medicine, tuberculosis, leprosy and syphilis are caused by excess heat. Heat diseases respond well to treatments that belong to the Metal element, such as Classical Western Medicine (CWM). It is thus CWM that is responsible for the decrease in tuberculosis, leprosy and syphilis in the modern world.
The increase in cancers can also be explained. In industrialized societies, the Metal element is very strong; this causes the Wood element to weaken, which increases the Earth element. Since cancer is caused by excess Earth, it is more likely to be prevalent in highly industrialized societies.