The majority of respiratory system cancers are attributable to smoking tobacco.The major histological types of respiratory system cancer are:

Small cell lung cancer
Non-small cell lung cancer
Adenocarcinoma of the lung
Squamous cell carcinoma of the lung
Large cell lung carcinoma
Other lung cancers (carcinoid, Kaposi’s sarcoma, melanoma)
Lymphoma
Head and neck cancer
Pleural mesothelioma, almost always caused by exposure to asbestos dust.In addition, since many cancers spread via the bloodstream and the entire cardiac output passes through the lungs, it is common for cancer metastases to occur within the lung. Breast cancer may invade directly through local spread, and through lymph node metastases. After metastasis to the liver, colon cancer frequently metastasizes to the lung. Prostate cancer, germ cell cancer and renal cell carcinoma may also metastasize to the lung. Treatment of respiratory system cancer depends on the type of cancer. Surgical removal of part of a lung (lobectomy, segmentectomy, or wedge resection) or of an entire lung pneumonectomy), along with chemotherapy and radiotherapy, are all used. The chance of surviving lung cancer depends on the cancer stage at the time the cancer is diagnosed, and to some extent on the histology, and is only about 14–17% overall. In the case of metastases to the lung, treatment can occasionally be curative but only in certain, rare circumstances. Benign tumors
Benign tumors are relatively rare causes of respiratory disease. Examples of benign tumors are:

Pulmonary hamartoma
Congenital malformations such as pulmonary sequestration and congenital cystic adenomatoid malformation (CCAM). Pleural cavity diseases
Pleural cavity diseases include pleural mesothelioma which are mentioned above.
While there are no safety issues identified, the findings are based on evidence limited by a small number of studies. Respiratory tract infections
Infections can affect any part of the respiratory system. They are traditionally divided into upper respiratory tract infections and lower respiratory tract infections. Upper respiratory tract infection
The upper airway is defined as all the structures connecting the glottis to the mouth and nose. The most common upper respiratory tract infection is the common cold. However, infections of specific organs of the upper respiratory tract such as sinusitis, tonsillitis, otitis media, pharyngitis and laryngitis are also considered upper respiratory tract infections. Epiglottitis is a bacterial infection of the larynx which causes life-threatening swelling of the epiglottis with a mortality rate of 7% in adults and 1% in children. Haemophilus influenzae is still the primary cause even with vaccinations. Symptoms include drooling, stridor, difficulty breathing and swallowing, and a hoarse voice.Croup (Laryngotracheobronchitis) is a viral infection of the vocal cords typically lasting five to six days. The main symptom is a barking cough and low-grade fever. On an X-ray, croup can be recognized by the "steeple sign", which is a narrowing of the trachea. It most commonly occurs in winter months in children between the ages of 3 months and 5 years. A severe form caused by bacteria is called bacterial tracheitis.Tonsillitis is swelling of the tonsils by a bacterial or viral infection. This inflammation can lead to airway obstruction.