1.Institute of Medical Oncology, University of Bern, 3010 Bern, Switzerland (DCB)
NSCLC is further divided histologically into three main disease subtypes of:
Whilst in certain countries, adenocarcinoma is now the most common disease subtype seen, in other countries, whilst the relative frequency of adenocarcinoma is rising, squamous cell carcinoma still predominates.
The observation that perhaps only 1-2 of every 10 smokers develops clinical lung cancer during their lifetime has been used as an argument to suggest that some level of genetic predisposition modifies disease risk. Whilst this argument is perhaps not compelling, it is not unreasonable and indeed a small number of genetic polymorphisms have been associated with modest increases in lung cancer risk. As lung cancer is usually caused by a chronic exposure of the bronchial epithelium to multiple procarcinogenic (and carcinogenic) agents, it is not surprising that many of these polymorphisms lie in genes associated with the activation (cytochrome P450s) or deactivation (Glutathione S-transferases) of such entities or the repair of subsequently induced damage (TP53). In general, epidemiological analysis has not suggested the existence of highly-penetrant, strongly-predisposing lung cancer associated genetic variants.
NSCLC: Treatment is based on the stage of the disease at presentation (which may be assessed by thoracic CT, PET scan, brain MRI). Stage I-II are usually resected (adjuvant chemotherapy can be discussed with the patient) and locally advanced stages (III) are treated by combined modality treatments (neoadjuvant chemotherapy, resection if stage IIIA or radiotherapy). If overt distant metastases are detected, therapy is palliative and chemotherapy has been shown to improve median survival and quality of life.
SCLC: If the tumour is confined to one hemithorax (limited disease), a combined modality therapy (chemo- and radiotherapy) is indicated: in more advanced disease (overt distant metastases in brain, liver, bones, surrenal glands or other organs) chemotherapy will be palliative though an excellent remission might be obtained in more than half of the patients.
New therapies based on an improved understanding of the molecular basis of the disease are currently in use or are under development. For example, Gefitinib, a tyrosine kinase inhibitor, is one such example that has been launched on the market in different countries for patients with relapsed or refractory NSCLC after chemotherapy. Further drugs with other defined molecular targets are anticipated.
Jim Heighway ; Daniel C Betticher
Lung tumors: an overview
Atlas Genet Cytogenet Oncol Haematol. 2004-02-01
Online version: http://atlasgeneticsoncology.org/solid-tumor/5030/lung-tumors-an-overview