Lunger cancer affects the lungs, that are used to expel carbon dioxide and bring in oxygen to breathe. Lung cancer begins in the tissue of the lungs with tumors. Most tumors are malignant. The tumors can block airways, making it hard for children to breath. Fluid is possible to accumulate, making it hard for the lungs to expand which can lead to pneumonia. If the lung cancer grows into the tops of the lungs it can affect nerves in the arm, neck, and face. With lung cancer comes a possibility of lung collapse.