Invasion and invasive can refer to a procedure that
requires an instrument or device to be inserted into the
body through the skin or through a body opening for
diagnosis or treatment. An example would be a needle
being inserted into a vein (a blood vessel that carries
blood to the heart). These terms can also mean the
beginning of a disease. Invasion also means the act of
spreading, entering, or intruding into, through, or
throughout something (such as healthy tissue). One
example would be a knife wound or gunshot wound.
An intravenous line is invasive.
FEATURED BOOK: Schwartz's Principles of Surgery

An invasion can slowly or rapidly filter into or through something else. Another example of
an invasion is the spreading, entrance, intrusion, or reproduction of microorganisms (tiny,
living organisms) into the body.

Yet another example is the local spread of a harmful growth of new cells or tissues that
serves no healthy function for the body (such as cancer). Cancer is a group of diseases
characterized by an abnormal and excessive growth of cells in one of the body organs or

Invasion and invasive are also used to describe the process by which harmful cells move
through the basement membrane and gain access to blood vessels and lymphatic

"Where Medical Information is Easy to Understand"™
The basement membrane is a thin sheet of fibers that form the bottom
of the epithelium. Epithelium is a group of cells that occur in one or more
layers, which cover the entire surface of the body and line most of the
hollow structures in it. Lymphatic channels are passageways that lymph
goes through. Lymph is a milky fluid that contains proteins, fats, and
white blood cells (which help the body fight off diseases). When the
term "invasion" is used to describe a growth of new cells or tissue in the
epithelium that serves no healthy function for the human body, it means
that the new tissue has spread to the bottom layer of the epithelium.
The opposite of invasive is non-invasive. Invasion and invasive come
from the Latin word "in" meaning "within," and the Latin word "vadere"
meaning "to go." Put the two words together and you have "to go