Lung cancer is the leading cause of cancer-related death in the world. In 2000 it was responsible for 17% of the 6.2 million deaths due to cancer worldwide according to the International Agency for Research on Cancer (IARC). In spite of advance in medical science, the incidence of the disease is growing steadily for 50 years, making it a serious global health concern.
Yet the tumor is one of the most preventable medical conditions in the world. Lung cancer is mainly caused by smoking, and continues to have a catastrophic prognosis despite real progress in the understanding of carcinogenesis made in therapy in recent years. The main and real solution remains abstinence of tobacco use and exposure, actively and passively.
There are two main types of lung cancer: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) which accounts for 15 to 20% of all lung cancers. This distinction is highly necessary the fact these two types of cancer have totally different characteristics: origin, aggressiveness, frequency of metastases, sensitivity to chemotherapy and radiotherapy (please see small cell lung cancer treatment).
Pulmonary small cell carcinomas are lung cancers that occur mainly in smokers, elderly as well as young individuals. The majority of cases are hilar (develop in the helium) or mediastinal pulmonary tumors; more rarely, they can present as a peripheral tumors (develop in areas away from the center of the lungs), or insolated (less than 10% of cases).
The tumor can spread intrathoracically or extrathoracically. Intrathoracic spreadof lung cancer can occureither by direct extension or by lymphatic metastasis; commonest sites of extrathoracic spreadof lung cancersare the supraclavicular and abdominal lymph nodes, liver, adrenal glands, brain, bone and skin. Small cell lung cancer is often accompanied by endocrine paraneoplastic syndrome (a set of signs and symptoms resulted from an advanced cancer in the body), leading to death within months in most cases. Please see Small cell lung cancer symptoms.
SCLC is different from other lung cancers by a set of characteristics:
• The tumor has high risk of relapse.
- High sensitivity to chemotherapy and radiotherapy.
- The cancerous cells reproduce extremely rapid, causing the tumor to double in size in about 30 to 40 days.
• The cancers tend to be neuroendocrine origin, forming in thecells of the endocrine (hormonal) and nervous systems.
- A very important metastatic power through lymphatic and blood stream, making it unnecessary to consider surgical therapeutic approach.
These characteristics make the originality of small cell lung cancer and rank it apart from other pulmonary carcinomas.