Humans - cancer of earth ?

I read somewhere that humans are the cancer of earth and it seems so true while reading the book "Germs, guns and steel" by Jared Diamond.
Let me start by stating the characteristics of cancer cells
1. These cells display uncontrolled growth.
2. Invasion and destruction of adjacent tissues.
3. Ultimately leads to death of the host.

Now if you think, humans exhibit all these traits. Homo sapiens have been growing and overpopulating the planet ever since the first human laid feet on the earth. Countless number of species are extinct due to their direct or indirect actions. In his book, Jared Diamond says that most of the mammals got extinct from Australia and Americas in short span just after humans made their first appearance there.
No other species has impacted the earth so much in its history of 4 billion years. And if the current rate of degradation continues, humans are bound to fulfill the third criteria as well.
The scars on earth's surface caused by humans are now visible from space. With the coming up of concrete cities, deforestation and melting glaciers and ice caps, the effect of human activities is all too visible.

The biggest difference though is that cancer cells do not realize that they are destructing their hosts, while humans do. And the worst part is that this does not change anything. Humans are too occupied with their own survival and conflicts to worry about the sustenance of the mother earth.
The only future that appears possible at the point is "start-over" !!