First, what is the definition of cancer? In humans, cancer is a group of diseases, where the division of cells occurs abnormally, uncontrollably, those cells are able to invade elsewhere (metastasize).
Not all tumors are cancer, there may be benign tumors, the benign tumor is not metastatic. Animals also have cancer. Cancer is often related to the genetic change in the cell nucleus (DNA).
Plants can also get cancer, due to various causes such as bacteria, viruses, fungi. Although cancer is also present, very little is affected by life because cancer cannot be metastasized in humans and animals but can only be developed locally.
In humans and animals, cancer cells move to other places through the system of blood vessels and lymphatic vessels to spread. Plants also have conductive circuits including xylene (for transporting water and dissolved substances) and phloem (for transporting sugar and amino acids). However, there are no cells in xylem and phloem, so cancer cells cannot spread.
In the heart xylem and phloem contain only water and nutrients, not plant cells.
In addition, plant cells have very hard membranes, so cancer cells, although thriving, are very difficult to destroy and invade surrounding organizations. Usually it can only be developed on the spot to a certain limit and surrounded by it, forming bulges in the leaves (gall) or stalks (burl) that our Vietnamese is often called NU as the grind , nuoc incense. The wood is often very hard and has a strange beauty.
Gall, cancer in the leaves.
A giant burl block in walnut.
Very beautiful wood grain image cut from burl.