Classification

There are different types of lung cancer, differing in their aggressiveness, course, and they should be treated differently accordingly.

Non-small cell lung cancer (NSCLC) is a very common form of lung cancer. Subtypes of non-small cell lung cancer:

• squamous epithelial carcinoma, originating from the uppermost layer of cells of the bronchial mucosa;
• adenocarcinoma arising from the glandular cells of the respiratory tract;
• large cell carcinoma of the lung, its origin is not clear.

Small cell lung cancer (SCLC) is rare compared to non-small cell lung cancer, with an incidence of approximately 15 out of 100 lung cancers. It often grows particularly rapidly and spreads early from the lungs outward to other organs.

In small cell lung cancer, only a limited stage (limited disease) and an extended stage (extended disease) are distinguished. A limited-stage tumor is defined as a tumor limited to one lung. Each form of tumor spread beyond one lung is referred to as an advanced stage.

Division into stages of non-small cell lung carcinomas

Based on the TNM classification according to a single international system, stages are distinguished from the first to the fourth.

• Stage I - it includes tumors that are locally limited, without damage to the lymph nodes and without distant metastases.
• At stage II, the tumor is still small, but there are already metastases in the lymph nodes. Also, stage II includes tumors that are slightly larger, but without metastases in the lymph nodes.
• Stage III refers to advanced tumors that have metastasized to the lymph nodes.
• Stage IV is characterized by the presence of distant metastases, regardless of whether the primary tumor in the lungs is small or large.

In turn, stage III is divided into stage IIIA (more often still operable) and stage IIIB, at which the operation is no longer possible. Stage IIIA has a further division, depending on the moment at which metastases are found in the lymph nodes. If they are found during examination before surgery - (IIIA3), during surgery - (IIIA2), or after surgery during histological examination of removed lymph nodes - (IIIA1). If the affected lymph nodes are particularly large or many independent lymph node clusters are affected, then they speak of stage IIIA4. Such a precise division into stages is important for the choice of treatment and the prognosis of the victims. For example, for patients with tumor stage IIIA4, surgery is not possible.

Stage division of small cell lung carcinomas

The distribution and staging of small cell lung carcinomas are also described using the TNM system. Sometimes a different classification is used, it distinguishes the limited distribution of the disease ("Limited disease", LD) from the extended stage ("Extensive disease", ED).

• In Limited disease, the tumor is on one side of the chest and is limited to one lung. This also applies to those cases when there is still a lesion of the lymph nodes of the other half of the chest.
• If the tumor has crossed the borders of one lung and sprouted into neighboring tissues or metastasized to other organs, then this is a "common" disease (ED).

K Limited disease refers to stages I-IIIB, to Extensive disease - stage IV.