Lung cancer. Coloured chest X-ray showing the left lung of a patient suffering from bronchoalveolar carcinoma, a form of lung cancer. The cancer is seen as a pneumonia-like shadow (blue, centre to lower right). Healthy lung tissue is orange/pink. Bronchoalveolar carcinoma originates in the pneumocyte cells that line the walls (septa) that separate the alveoli, the small air sacs in which gaseous exchange occurs. Symptoms of lung cancer include chest pain, shortness of breath, a cough and weight loss. If the cancer has not spread (metastasised) to other tissues, then it may be removed surgically. Other treatments include chemotherapy (anti-cancer drugs) and radiotherapy.