Stages of Lung Cancer
Lung cancer is divided into two main types: non-small cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). Since the management of cancer depends greatly on the extent of the disease—encapsulated tumor versus widespread metastatic disease, for example—oncologists have developed staging systems for virtually every type of cancer, including lung cancer. The behavior of NSCLC and SCLC in the body are quite different and are treated in very different ways, thus their staging systems are different.
Staging of Non-Small Cell Lung Cancer (NSCLC)
Cancer staging of non-small cell lung cancer NSCLC is based on a number of clinical findings, diagnostic studies, and laboratory findings. Since accurate staging in lung cancer is extremely important, particularly in NSCLC, once a diagnosis is made additional testing will be done to properly classify the tumor. Staging for lung cancer takes into consideration:
- The patient’s medical, family, and social history
- Findings on physical examination
- Blood tests: Complete blood count (CBC), Serum electrolytes (CMP; Chem-10), Liver function tests (LFTs)
- Radiological studies: Chest X-ray, Chest CT (possibly abdomen and pelvis also)
If the oncologist suspects a distant metastasis of the lung cancer based on history and physical exam, additional tests may be considered for the purposes of NSCLC staging. Positron emission tomography (PET) scanning is used to look for collections of cancerous cells throughout the body. Bone scintigraphy can be used if metastasis to bone is suspected and magnetic resonance imaging (MRI) is performed when the brain or spine are likely compromised by spread of the primary tumor.
Identifying the histological type of NSCLC tumor cell is important as well, which means that a pathological diagnosis is required. In order to obtain a pathological diagnosis, a biopsy of the tumor must be taken. This can be done through bronchoscopy, thoracosopy, fluoroscopic-guided biopsy, or open thoracotomy (rarely).
There are four stages in NSCLC, Stage I through Stage IV. Stages I, II, and III are further divided into A and B subtypes. Technically there is also a fifth stage, Stage 0, which is not an invasive cancer. These numbered stages are assigned based on a TNM staging system. TNM is an acronym that stands for Tumor, Node, and Metastasis. TNM staging is used to stage virtually every type of cancer; however, each TNM classification correlates to different stages across various types of cancer. In other words, Stage III lung and breast cancer may have different TNM stages.
| TNM Staging System for Non-Small Cell Lung Cancer* | ||
|---|---|---|
| Tumor (T) | Tx | Positive malignant cytology, no visible lesion by radiology |
| T1 | Tumor 3cm in diameter or less | |
| T2 | Tumor more than 3cm in diameter | |
| T3 | Tumor growing into pleura, chest wall, diaphragm, pericardium | |
| T4 | Chemotherapy (adjuvant), radiation therapy (primary or adjuvant) | |
| Lymph Node Involvment (N) | N0 | Neoadjuvant chemotherapy and radiation |
| N1 | Bronchopulmonary or hilar nodes involved on tumor side of lung | |
| N2 | Mediastinal or subcarinal nodes involved on tumor side of lung | |
| N3 | Nodes in the opposite lung from the primary tumor | |
| Metastasis (M) | M0 | No Metastases |
| M1 | Metastases | |
| * Based on 1997 guidelines. International Association for the Study of Lung Cancer is expected to release new TNM stagin guidelines within the next year. | ||
Once the size of the primary tumor is known, whether there are local/regional lymph nodes containing cancer cells, or if there are distant cancer cells (metastasis), the TNM classification is used to assign a stage based on the four-tiered scale.
| Stage Grouping Correlated TNM Stagin System for Non-Small Cell Lung Cancer* | ||
|---|---|---|
| Stage 0 | Cells, No Tumor | Carcinoma in situ |
| Stage IA | T1 N0 M0 | Tumor 3cm in diameter or less, No lymph node spread |
| Stage IB | T2 N0 M0 | Tumor > 3cm in diameter, No lymph node spread |
| Stage IIA | T1 N1 M0 | Tumor 3cm in diameter or less, Local lymph node spread |
| Stage IIB | T2 N1 M0 OR T3 N0 M0 |
Tumor > 3cm in diameter, Lymph node spread OR Tumor invaded surrounding structures, No lymph node spread |
| Stage IIIA | T3 N1 M0 OR T1-3 N2 M0 |
Tumor invaded surrounding structures, Local lymph node spread OR Regional lymph node spread, any T stage (except 4) |
| Stage IIIB | Any T4 OR Any N3, M0 | Tumor invading mediastinum OR Lymph node spread to opposite lung |
| Stage IV | Any M1 | Any metastasis |
| * Based on 1997 guidelines. International Association for the Study of Lung Cancer is expected to release new TNM stagin guidelines within the next year. | ||
Treatment for NSCLC is based largely on the stage of the disease according to these four stages. While there are guidelines for what therapy should be used in a particular NSCLC stage, significant variability exists between oncologists since treatment is tailored to the needs and wishes of the patient. The table includes treatment for the first occurrence of NSCLC only (not recurrence). Also, if the lung cancer is causing significant, intractable pain or if the tumor is causing functional problems with other organs like the heart or brain, additional treatment may be used to reduce symptoms (rather than try for a cure).
| Treatment Guidelines for Non-Small Cell Lung Cancer | ||
|---|---|---|
| Stage | Standard Treatment | Alternate Theraphy, clinical trials, for symptom control, or palliation |
| Stage 0 | Surgical resection | Endoscopic surgery, laser therapy, electrosurgery, cryosurgery |
| Stage IA | Surgical resection | Chemotherapy (adjuvant), radiation therapy |
| Stage IB | Surgical resection | Chemotherapy (adjuvant), radiation therapy |
| Stage IIA | Surgical resection | Chemotherapy (adjuvant), radiation therapy (primary or adjuvant) |
| Stage IIB | Surgical resection | Chemotherapy (adjuvant), radiation therapy (primary or adjuvant) |
| Stage IIIA | Surgery then chemotherapy Chemotherapy and radiation |
Neoadjuvant chemotherapy and radiation |
| Stage IIIB | Chemotherapy and radiation | |
| Stage IV | Chemotherapy Radiation therapy (palliative) Surgical resection (palliative) |
Combination therapy, internal radiation, targeted therapy, laser therapy |
| * Based on 1997 guidelines. International Association for the Study of Lung Cancer is expected to release new TNM stagin guidelines within the next year. | ||
Staging of Small Cell Lung Cancer (SCLC)
Unlike non-small cell lung cancer (and most cancers), it does not help oncologists or other medical professionals to use the TNM staging system to describe small cell lung cancer (SCLC). Currently, experts agree that it is more useful to separate SCLC into two stages: limited stage and extensive stage. This does not mean that the staging workup is less involved; in fact, there may be more tests and studies done for the purpose of staging SCLC than NSCLC. The staging workup of SCLC involves:
- Complete history
- Complete physical examination
- Blood tests
- Complete blood count (CBC) with differential
- Serum chemistry including blood urea nitrogen, creatinine, calcium, alkaline phosphatase(CMP; Chem-10)
- Liver function tests (LFTs)
- Serum lactate dehydrogenase (LDH)
- Chest X-ray
- CT of chest, abdomen and pelvis
- MRI of brain (in most cases)
- Bone scan
- Bone marrow aspiration (if it will help direct treatment based on the rest of the workup)
There have been some discrepancies and disagreements about what constitutes limited stage SCLC. The most common definitions for both stages are listed, but individual oncologists may have slightly different definitions regarding the precise scope of limited stage SCLC.
Limited Stage
Limited stage disease is small cell lung cancer that is confined to one half of the chest, essentially. This can include any location within one lung, the entire mediastinum, and local lymph nodes. The National Cancer Institute defines local lymph nodes as those that can be reached with a single radiation that also treats the primary tumor. If cancer cell-containing lymph nodes are outside of the radiation port, the affected patient would warrant extensive stage status. A malignant pleural effusion qualifies as extensive stage.
Extensive Stage
Extensive stage small lung cancer is disease that cannot be included within or exceeds the limited stage criteria. It generally indicates cancer has spread to the opposite lung or to distant sites in the body. Metastatic lung cancer is a very challenging problem for the treating oncologist.
Treatment of lung cancer is based mostly on whether the cancer is limited or extensive stage. Small cell lung cancer tends to be very sensitive to radiation therapy, which means if it can be treated with a single radiation port, it should be tried. Generally radiation therapy is only used to treat limited stage SCLC. Surgery is rarely indicated in either limited or extensive stage SCLC. Chemotherapy is indicated in both SCLC stages, however the particular stage does guide which chemotherapeutic drugs should be used. Various chemotherapy regimens have been tried and continue to be used in SCLC. The major distinction is that sometimes only one drug can be used to treat limited stage disease when combined with radiation therapy while extensive stage disease is treated with more than one chemotherapeutic drug.