1. Restricting diet: Restricting the diet in an attempt to starve cancer cells is a misconception. Limiting diet can lead to malnutrition, weaken the immune system, and even accelerate tumor progression. 

2. Soup is the most nutritious: Some cancer patients believe that soup is more nutritious than solid food.

However, soup is only rich in purines, fats, salt, and vitamins. The nutritional value of meat in soup sediment is actually higher.

Consuming only soup without the meat can result in protein and energy deficiency, worsening malnutrition. 

3. Excessive intake of supplements: Many patients rely heavily on supplements to fight cancer and boost immunity.

However, expensive supplements often have more commercial hype than nutritional value.

There is no evidence to suggest that they enhance the immune system of cancer patients.