TYPES AND STAGING OF LUNG CANCER

There are several different types of lung cancer and various staging systems, as described below. Treatment may be determined by the type and stage that is given to the tumor when the cancer is diagnosed.

Primary Lung Cancer

Together, non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) account for 95% of all lung tumors. These two types of tumors are malignant in character, whereas the remaining 5% of lung tumors may be malignant or benign.

NON-SMALL CELL LUNG CANCER

Squamous Cell Carcinoma
  • 20%–30% of all lung cancers
  • Centrally located
  • Produces early symptoms of nonproductive cough and hemoptysis
  • Does not tend to metastasize
  • Depending on stage at diagnosis, may be treated by surgical resection, radiation, and/or systemic therapies
  • Depending on the staging upon diagnosis, life expectancy tends to be better than with small cell lung cancer
  • Slow growth rate
Adenocarcinoma
  • 30%–40% of all lung cancers
  • Most common lung cancer in nonsmokers
  • Peripherally located
  • Usually no symptoms until there is considerable metastasis
  • Depending on the staging upon diagnosis, may be treated by surgical resection, radiation, and/or systemic therapies
  • Moderate growth rate
Large Cell (Undifferentiated) Carcinoma
  • 10% of all lung cancers
  • Large anaplastic cells
  • Often located in the bronchi
  • Highly metastatic via blood and lymphatic system
  • Surgery not usually a credible option because of the high rate of metastasis to other organs
  • Tumor may respond well to radiation therapy but has a high rate of recurring
  • Rapid growth rate

SMALL CELL CARCINOMA

  • <20% of all lung cancers
  • Most malignant type of lung cancer
  • Early metastasis via blood and lymphatic system
  • Frequently metastasizes to the brain
  • Treated with systemic therapies, but the prognosis is still usually poor
  • Radiation therapy may be used in addition to systemic therapies or as a palliative measure to reduce symptoms
  • Is usually not considered resectable as it is so fast-growing
  • Related to endocrine disorders

Other Lung Tumors

MESOTHELIOMAS

  • May be malignant or benign tumors
  • Malignant tumors are related to exposure to asbestos
  • Arise from the visceral pleura
  • Benign mesotheliomas are localized lesions

HAMARTOMAS

  • Most common type of benign lung tumor
  • Slow-growing type of congenital tumor
  • Composed of fibrous tissue, fat, and blood vessels

MUCOUS GLAND ADENOMA

  • Benign tumor in the bronchi
  • Composed of columnar cystic spaces
    (Harding et al., 2020)

Staging Non-Small Cell Lung Cancer

Following diagnosis with lung cancer, clinicians describe the extent of the cancer by designating its “stage.” Staging is then used in planning appropriate interventions. Patients with NSCLC in stages I, II, and IIA are viable candidates for surgery since their malignancy is not too advanced. Patients with stages IIIB and IV cancer are inoperable and have a poor prognosis (Harding et al., 2020).

TUMOR STAGING
(Harding et al., 2020)
Stage I Tumor is small and localized to the lung, with no lymph node involvement
A Tumor <3 cm
B Tumor 3–5 cm and invading surrounding local areas
Stage II Increased tumor size, some lymph node involvement
A Tumor 3–5 cm with lymph node involvement on same side of chest OR
Tumor 5–7 cm without lymph node involvement
B Tumor 5–7 cm involving the bronchus and lymph nodes on the same side of the chest and tissue of other local organs OR
Tumor >7 cm without lymph node involvement
Stage III Increased spread of tumor
A Tumor spread to the nearby structures (chest wall, pleura, pericardium) and regional lymph nodes
B Extensive tumor involving heart, trachea, esophagus, mediastinum, malignant pleural effusion, contralateral lymph nodes, scalene or supraclavicular lymph nodes
Stage IV Distant metastasis

The TNM tumor classification system further evaluates tumors according to tumor size and invasiveness (T), regional spread to the lymph nodes (N), and metastasis (M). These designations are used for both SCLC and NSCLC, although it is generally not as important for SCLC because this cancer is aggressive and systemic. The stages of SCLC are limited, as the tumor is only on one side of the chest and an extensive disease.

TNM TUMOR STAGING SYSTEM
(Lewis et al., 2020)
Primary Tumor (T)
T0 No evidence of primary tumor
Tis Carcinoma in situ (IS)
T1–T4 Ascending degrees of increase in tumor size and involvement
Tx Tumor cannot be measured or found
Regional Lymph Nodes (N)
N0 No evidence of disease in lymph nodes
N1–N4 Ascending degrees of nodal involvement
Nx Regional lymph nodes unable to be assessed clinically
Distant Metastases (M)
M0 No evidence of distant metastasis
M1–M4 Ascending degrees of metastatic involvement, including distant nodes
Mx Cannot be determined

(See also “Resources” at the end of this course.)