1. Hot dogs : Because they are high in nitrates, the Cancer Prevention Coalition advises that children eat no more than 12 hot dogs a month. If you can’t live without hot dogs, buy those made without sodium nitrate.
2. Processed meats and bacon: Also high in the same sodium nitrates found in hot dogs, bacon, and other processed meats raise the risk of heart disease. The saturated fat in bacon also contributes to cancer.
3. Doughnuts: Doughnuts are cancer-causing double trouble. First, they are made with white flour, sugar, and hydrogenated oils, then fried at high temperatures.
4. French fries: Like doughnuts, French fries are made with hydrogenated oils and then fried at high temperatures. They also contain cancer- causing acryl amides which occur during the frying process.
5. Chips, crackers, and cookies: All are usually made with white flour and sugar. Even the ones whose labels claim to be free of trans-fats generally contain small amounts of trans-fats.
6. Sugar is a cancer-feeder. By cutting off sugar it cuts off one important food supply to the cancer cells. Sugar substitutes like NutraSweet, Equal,Spoonful, etc are made with Aspartame and it is harmful. A better natural substitute would be Manuka honey or molasses but only in very small amounts. Table salt has a chemical added to make it white in color. Better alternative is Bragg’s aminos or sea salt.
7. Cancer cells thrive in an acid environment. A meat-based diet is acidic and it is best to eat fish, and a little chicken rather than beef or pork. Meat also contains livestock antibiotics, growth hormones and parasites, which are all harmful, especially to people with cancer.

INSTEAD TRY

• A diet made of 80% fresh vegetables and juice, whole grains, seeds, nuts and a little fruits help put the body into an alkaline environment. About 20% can be from cooked food including beans. Fresh vegetable juices provide live enzymes that are easily absorbed and reach down to cellular levels within 15 minutes to nourish and enhance growth of healthy cells.  To obtain live enzymes for building healthy cells try and drink fresh vegetable juice (most vegetables including bean sprouts) and eat some raw vegetables 2 or 3 times a day. Enzymes are destroyed at temperatures of 104 degrees F (40 degrees C).
• Avoid coffee, tea, and chocolate, which have high caffeine. Green tea is a better alternative and has cancer-fighting properties. Water–best to drink purified water, or filtered, to avoid known toxins and heavy metals in tap water.
• Some supplements build up the immune system (anti-oxidants, vitamins, minerals etc.) to enable the body’s own killer cells to destroy cancer cells. Other supplements like vitamin E are known to cause apoptosis, or programmed cell death, the body’s normal method of disposing of damaged, unwanted, or unneeded cells.
• Cancer is a disease of the mind, body, and spirit. A proactive and positive spirit will help the cancer warrior be a survivor. Anger, unforgiveness and bitterness put the body into a stressful and acidic environment. Learn to have a loving and forgiving spirit. Learn to relax and enjoy life.
• Cancer cells cannot thrive in an oxygenated environment. Exercising daily, and deep breathing help to get more oxygen down to the cellular level. Oxygen therapy is another means employed to destroy cancer cells.

Source: multiple sources