Breast Cancer
The breasts are the most prominent superficial structures in the anterior thoracic wall, especially in women. Both men and women have breasts, but they are normally well developed only in women. The breast consists of glandular and supporting fibrous tissue embedded within a fatty matrix, together with blood vessels, lymphatics, and nerves. Mammary glands are present in the breast in the subcutaneous tissue. They are functionless in men, but are accessory to reproduction in women. The nipple of the breast is surrounded by the areola.
Carcinomas of the breast are malignant tumors that usually arise from the mammary gland lobules or ducts. Over time, cancer cells can metastasize, and invade nearby healthy breast tissue and make their way into the axillary lymph nodes, and on to the venous system. Breast cancer cells typically spreads by the means of lymphatic vessels. Breast cancer is always caused by a genetic mutation, but only 5-10% of mutations are genetic, while the other 90% occur as a result to the aging process or normal life processes. Breast cancer is categorized into five main stages that refer to how far the cells have spread. In the first stage, Stage 0, cancer cells remain within the breast duct, and have not invaded normal breast tissue. The stages progress to stage IV, where the cancer has metastasized to other areas of the body. Breast cancers are most common in women, about 1.5% of breast cancers occur in men.
Lung Cancer
The lungs are the vital organs of respiration. Their main function is to exchange oxygen and carbon dioxide with a tidal airflow. The oxygenated blood is then sent to the heart and distributed to the body. The pulmonary cavity houses the lungs, and it is completely lined by membranous parietal pleura that reflects onto the lungs at their roots, and becomes the visceral pleura which covers the lungs surface. Pleural fluid is between to two layers, and it prevents the lungs from collapse and causes the lungs to expand when the thorax expands for inhalation. Both lungs are pyramidal in shape, but the right lung has three lobes and the left lung has two. Air enters the lungs from the trachea which bifurcates at the level of the thoracic plane into the main bronchi. The main bronchi branch into lobar bronchi which then branch into segmental bronchi. The segmental bronchi lead to terminal bronchioles and eventually to pulmonary alveolus which is the basic structural unit of gas exchange in the lung.
Lung cancer is mainly caused by cigarette smoking. Most cancers arise in the mucosa of the large bronchi and produce a persistent, productive cough. Malignant tumors metastasize to the bronchompulmonary lymph nodes, and then onto other thoracic lymph nodes. If the tumor cells reach the blood, common sites of metastasis are the brain, bones, lungs, and suprarenal glands. It is possible that the tumor cells enter the systemic circulation by invading the wall of a venule in a lung and are transported through the pulmonary veins, left heart, and aorta. Even though tobacco is the primary cause of lung cancer, other risks include radon, asbestos, air pollution, family history, personal history, and age over 65.
Pulmonary collapse
The lungs are elastic, and recoil to approximately 1/3 of their size when the thoracic cavity is opened. Normal lungs remain are distended, even when the air passages are open, because the visceral pleura of the lungs adhere to the inner surface of the thoracic walls as a result of the surface tension provided by the pleural fluid. The pressure in the pleural cavity is sub-atmospheric because of the elastic recoil of the lungs.
Pneumothorax is the entry of air into the pleural cavity and results in lung collapse. It usually results from penetrating wound of the parietal pleura or from rupture of a pulmonary lesion into the pleural cavity. Fractured ribs may also tear the visceral pleura and lung producing pneumothorax. When a lung collapses, it expels most of its air because of its elastic recoil. Laceration or rupture of the surface of the lung or penetration of the thoracic wall results in hemorrhage and the entrance of air into the pleural cavity. The amount of blood and air that accumulated determines the extent of the pulmonary collapse. When a lung collapses, it occupies less volume within the pulmonary cavity, and the pulmonary cavity does not increase in size during inspiration.
Sources:
Clinically Oriented Anatomy
http://www.breastcancer.org/symptoms/understand_bc/what_is_bc.jsp
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