Mitochondria contain a large number of radicals. The good thing is that these radicals are safely tucked away on the inside of a cell wall which comprises the mitochondria.
In cell death, the cell wall sometimes fractures. I haven't been reading up on mitochondrial research recently, so I can't place the timing of the cell wall rupture prior to the cell death (which might indicate it is a causal relationship) or after the cell death (which would indicate a consequence of the preceding death). In either case, without a functioning mitochondria, nearly 80% of the energy available from glucose is unattainable, so mitochondrial damage and cell death are closely related.
One problem with combating cancer is that it's an overly broad description which applies to any unwanted / unregulated growth. Any malfunction of the cell where it stops responding to cues that regulate growth is called cancer. Normal cells detect their neighbors and slow down the growth process, while cancerous cells grow regardless of feedback signal(s). Sometimes this leads to localized starvation of sugars, oxygen, or other resources.
Human cells have a fail-safe in that they contain a protein p53 which is triggered under certain circumstances. This protein signals the cells to "cellularly age" meaning the cell will no longer be able to reproduce, but will maintain and repair itself. This cellular aging is based on a clock which seems to count its time in number of divisions. It has been a long time since I did such research, but if I recall correctly, a cell has about 90 divisions prior to aging.
Some cancers manage to disrupt this safeguard, and they are referred to as "growths", "benign tumors", "dead cancer cells", "non-cancerous tumors", etc. while active growths are generally referred too as cancer. In the research fields we view(ed) reality as it all being cancer, but some of it was "arrested".
There is a theory that cancer can be induced by damaging cellular components with free radicals. A leak in a mitochondria might allow damage to a cell, and depending on what is damaged (and to what degree) it might actually trigger a cancer. While the possibility exists, rest assured that it is so small that you manage to carry around multiple millions of cells for upwards of 80 years without guaranteeing that it will happen in a single cell.
This free radical theory is the reason why people believe that eating anti-oxidants can promote better health; however, I am not aware of any research (due to ignorance, not necessarily because it is a false theory) that indicates that anti-oxidants survive the transition from stomach to bloodstream, or that they get internalized from the bloodstream to the cellular cytoplasm.
While the public "knows" that cancer is a growth of existing cells, the entire public reaction is to deal with the problem as a disease. This dichotomy might be the reason that the public has so many misconceptions about cancer. We "catch cancer" and "get rid of it" in casual talk; but, in reality (with the exception of a very few viral cancers) there is no outside agent: one might as well be talking about catching a lung or a kidney. It requires quite a bit of discipline to readjust our thinking to "our bodies are malfunctioning".
As far as mitochondria, their role is to provide a cellular membrane where the process of the electron transport chain can occur. That provides both energy and free radicals. The energy is not tagged for a particular consumer, and a the cell that needs it to survive is the same cell that will use it when malfunctioning in a manner we call cancer.
