There are many factors involved with the development of cancer. Here are a few.

pH and Cancer:  Acidic pH Levels Can Lead To Cancer...
Cancer thrives in an acidic environment and cannot survive in an alkaline environment. Cancer cells make your body even more acidic as they produce lactic acid. So if you have cancer, your pH levels are low and your body is too acidic.
When your blood starts to become acidic, your body deposits toxins into the cells to allow the blood to remain slightly alkaline. This causes your cells to become more acidic and toxic, which results in a decrease of their oxygen levels, and harms their DNA and respiratory enzymes.

The immune system and cancer. For most of your life, your immune system successfully fought cancerous cells, killing them as they developed. That's its job. In fact, the only job Natural Killer cells have is to kill cancer cells and viruses. For cancer to develop, your immune system must either be worn out, ineffective, unable to kill cancer cells as fast as they normally develop, or you must be exposed to a mass of cancer causing toxins, radiation or some such thing, that increase the rate of development of cancer cells to an abnormally high level that your immune system can't handle. Either way, it is vital to strengthen the immune system in your battle against cancer . Especially if you are getting medical treatments that wipe out your immune system.

Oxygen and Cancer:  Low Oxygen Levels Breed Cancer...
The link between oxygen and cancer is clear. Low oxygen levels in cells may be a fundamental cause of cancer. There are several reasons cells become poorly oxygenated. An overload of toxins clogging up the cells, poor quality cell walls that don't allow nutrients into the cells, the lack of nutrients needed for respiration, poor circulation and perhaps even low levels of oxygen in the air we breathe. In newly formed cells, low levels of oxygen damage respiration enzymes so that the cells cannot produce energy using oxygen. The prime cause of cancer is the replacement of the respiration of oxygen in normal body cells by a fermentation of sugar. All normal body cells meet their energy needs by respiration of oxygen, whereas cancer cells meet their energy needs in great part by fermentation.

When the mitochondrial enzymes get destroyed, the host cell can no longer produce all its energy using oxygen. So, if the cell is to live, it must ferment sugar to produce energy. For a short period of time this anaerobic fermentation of sugar is okay and your cells recover and produce energy using oxygen. However the problem comes when your cells cannot produce energy using oxygen because of this damage to the respiratory enzymes. Then they must produce energy primarily by fermentation most of the time. Cancer cells produce excess lactic acid as they ferment energy. Lactic acid is toxic, and tends to prevent the transport of oxygen into neighboring normal cells. Over time as these cells replicate, the cancer may spread if not destroyed by the immune system.This is what can cause a cell to turn cancerous.

Over time these cells increase in acidity and some die. These dead cells themselves turn into acids. However, some of these acidified cells may adapt in that environment. In other words, instead of dying - as normal cells do in an acid environment - some cells survive by becoming abnormal cells. These abnormal cells are called malignant cells. Malignant cells do not correspond with brain function nor with our own DNA memory code. Therefore, malignant cells grow indefinitely and without order. This is cancer.

Fungus and Cancer: Candida And Fungal Infections May Cause Cancer...
Candida or other systemic fungal infections cause or at the very least contribute to the development of cancer. A candida infection plays havoc on the immune system. Not only does the immune system become overwhelmed and worn out from fighting the infection, but candida (or other fungus) excrete toxins that further weaken and harm the body. The major waste product of candida is acetaldehyde, which produces ethanol which causes excessive fatigue, and reduces strength and stamina. In addition, it destroys enzymes needed for cell energy, and causes the release of free radicals that can damage DNA.
Ethanol also inhibits the absorption of iron. Because iron is one of the most important oxygen supports in the blood, ethanol in your body creates low oxygen levels. And you know what happens when your body can't oxygenate well. 

An important property of blood is its degree of acidity or alkalinity. The body's balance between acidity and alkalinity is referred to as the acid-base balance. The kidneys and lungs work to keep the acid-base balance healthy. Acid and alkaline levels are measured on a pH scale. An increase in acidity causes pH levels to fall. An increase in alkaline causes pH levels to rise.
The blood's acid-base balance is precisely controlled because even a minor deviation from the normal range can severely affect many organs.
The role of the lungs. One mechanism the body uses to control blood pH involves the release of carbon dioxide from the lungs. Carbon dioxide, which is mildly acidic, is a waste product of the metabolism of oxygen (which all cells need) and, as such, is constantly produced by cells. As with all waste products, carbon dioxide gets excreted into the blood. The blood carries carbon dioxide to the lungs, where it is exhaled. As carbon dioxide accumulates in the blood, the pH of the blood decreases (acidity increases). The brain regulates the amount of carbon dioxide that is exhaled by controlling the speed and depth of breathing. The amount of carbon dioxide exhaled, and consequently the pH of the blood, increases as breathing becomes faster and deeper. By adjusting the speed and depth of breathing, the brain and lungs are able to regulate the blood pH minute by minute.

The role of the kidneys. The kidneys are able to affect blood pH by excreting excess acids or bases. The kidneys have some ability to alter the amount of acid or base that is excreted, but because the kidneys make these adjustments more slowly than the lungs do, this compensation generally takes several days.

Respiratory acidosis and alkalosis are due to a problem with the lungs. Metabolic acidosis and alkalosis are due to a problem with the kidneys.

The role of the kidneys and the lungs in maintaining

optimal ph levels.