TNM Staging for Lung Cancer
Tis – Pre-cancerous changes or carcinoma in situ. No spread to nearby lymph nodes or distant body parts. T1mi– Cancer is minimally invasive adenocarcinoma </=3 cm in greatest dimension and invasion </=5 mm in greatest dimension. No spread to nearby lymph nodes or distant body parts. T1a – A tumor </=1 cm in the greatest dimension without invasion of the pleural membrane or main bronchus. No spread to nearby lymph nodes or distant body parts. T1b – A tumor >1 cm but </=2 cm in the greatest dimension without invasion of the pleural membrane or main bronchus. No spread to nearby lymph nodes or distant body parts. T1c – A tumor >2 cm but </=3 cm in the greatest dimension without invasion of the pleural membrane or main bronchus. No spread to nearby lymph nodes or distant body parts. T2a – A tumor >3 cm but </=4 cm in the greatest dimension that: · has invaded into the main bronchus but has not affected the carina (the point where the trachea divides into the 2 bronchi), or · invades the visceral pleura, or · is partially choking the airway T2b – A tumor >4 cm but </=5 cm in the greatest dimension that: · has invaded into the main bronchus but has not affected the carina (the point where the trachea divides into the 2 bronchi) · has grown into the visceral pleura · is partially choking the airway T3 – A tumor >5 cm but </=7 cm in the greatest dimension that has invaded into the parietal pleura, chest wall, phrenic nerve, or the membranes surrounding the heart (parietal pericardium); or There are 2 separate primary tumor nodules within the same lobe. T4 – A tumor >7 cm in the greatest dimension that has invaded into the diaphragm, mediastinum, heart, large blood vessels, trachea, recurrent laryngeal nerve, esophagus, backbone, or carina; or there is another tumor nodule in the adjacent lobe of the same lung.
Regional lymph node metastases precede systemic dissemination. In lung tissue, lymphatic drainage parallels the bronchoarterial system, with lymph nodes situated adjacent to the segmental or lobar bronchi. In general, lower lobe lymphatics drain to the posterior mediastinum and the subcarinal lymph nodes. Right upper lobe lymphatics drain toward the superior mediastinum. Left upper lobe lymphatics typically course lateral to the aorta and subclavian artery in the anterior mediastinum, as well as along the left main bronchus to the superior mediastinum. Ultimately, all of these lymphatic channels drain into the right lymphatic or left thoracic ducts, which empty into the subclavian veins. Although skip metastases can occur, antegrade lymphatic metastases most commonly exhibit sequential involvement of bronchopulmonary (N1), mediastinal (N2 and N3), and supraclavicular (N3) lymph nodes. Retrograde lymphatic spread to the pleural surface can occur, particularly with peripheral tumors. Metastases within the lung result from a variety of mechanisms including endobronchial embolization, retrograde lymphatic, as well as hematogenous dissemination. N0 – No spread of cancer to nearby lymph nodes N1 – Cancer has spread to nearby lymph nodes within the lung or along the bronchus or around the area where the bronchus enters the lung N2 – Cancer has spread to subcarinal or ipsilateral mediastinal lymph nodes N3 – Cancer has spread to mediastinal lymph nodes on the other side of the primary tumor, or nodes near the collarbone (supraclavicular nodes)
M0 – Cancer has not spread to distant body parts M1a – Spread of cancer cells into the pleura or pleural fluid (malignant pleural effusion) or into the pericardium or pericardial fluid (malignant pericardial effusion). M1b – Single tumor deposit in a single distant organ (for example, liver, bones, brain, etc) or to a non-regional lymph node. M1c – Multiple tumor deposits in single or multiple distant organs.
Staging for Small Cell Lung Cancer
Additionally, SCLC is divided into following 2 stages based on the extent of disease spread and type of treatment approach to be followed:
This means that cancer is only on one side of the chest and might have spread to lymph nodes (including lymph nodes above the collarbone) on the same side.
This type of SCLC is generally confined to a specific small region of the lung that can be treated with a single radiation field.
This means that cancer has extensively spread throughout the lung, to other lung, lymph nodes on the other side of the chest, pleural membrane, distant lymph nodes, or distant organ.
This type of SCLC cannot be treated with a single radiation therapy and require chemotherapy for their management.
Treatment of NSCLC (NON SMALL CELL LUNG CANCER)
The treatment of NSCLC mainly depends on the stage, type, location of the tumor, pulmonary function, performance status of the patient, presence of certain genetic abnormalities, along with other factors.
Following is the preferred treatment approach for different stages of NSCLC, but the final decision is taken after clinical assessment of the patient by an oncologist.
Lung Cancer Treatment Options according to stage
Stage 0 (Tis N0 M0)
Stage 0 NSCLC is limited to the superficial layer of the airway and can be treated by surgery alone as the standard treatment. Sometimes, endobronchial therapies like photodynamic therapy (PDT), laser therapy, or brachytherapy may be employed to treat Stage 0 NSCLC.
Surgery resection with mediastinal lymph node dissection is the standard treatment. Chemotherapy may be added in selected cases. In inoperable cases (poor lung reserve, poor performance status, etc), radiation therapy may be employed as the primary treatment.
Surgical resection with mediastinal lymph node dissection is done, while preoperative chemoradiation may be considered in selected cases. Chemotherapy should be considered after surgery. In inoperable cases, chemotherapy and/or radiotherapy may be given.
Stage III NSCLC treatment generally includes a combination of surgery, radiation therapy, and chemotherapy. The overall treatment approach depends on the size and location of the tumor, the location of the lymph node involved, and overall health status of the patient.
Stage IV (Metastatic disease)
Chemotherapy, targeted therapy or immunotherapy is the mainstay of treatment. Other treatment options like surgery, radiation therapy or bone-directed therapy may be considered for palliation or relief of symptoms.
This brings us to the end of treatment for lung cancer. Now let’s discuss the various treatment modalities for lung cancer in detail.
Brief description of various treatment modalities employed for NSCLC:
Surgery is the treatment of choice for early stage and some advanced stage lung cancers that have not spread to distant body parts and can be completely removed. For early-stage disease, a tumor can be removed with segmentectomy, wedge resection, or sleeve resection, where only a part of the affected lobe is removed. In case of advanced stage disease, lobectomy (surgical removal of the entire globe) or pneumonectomy (surgical resection of the entire lung) may be required depending on the size and location of the tumor. Surgery can also be employed as a palliative treatment for an advanced-stage disease to relieve airway obstruction by a growing tumor.
Radiation therapy (or radiotherapy) uses high-energy radiation directed to the affected area to kill cancerous cells. It can be employed either by using an external radiation source (external beam radiation therapy) or by directly placing the source of radiation near the cancer tissue (brachytherapy). Sometimes, it is used as palliative therapy to relieve pain, bleeding, and obstructive problems associated with the advanced-stage disease.
Chemotherapy means treatment with anti-cancer drugs that kill or decrease the growth of rapidly growing cancer cells. It is considered to be the mainstay of treatment for advanced stage disease that has spread to distant body parts. Depending on the physician’s preference and patient’s condition, it may also be combined with other treatment options to accelerate the benefit achievement. It may be used in the neoadjuvant (prior to surgery), adjuvant (after surgery) and palliative (metastatic disease) settings. It may be associated with side effects like nausea/vomiting, hair loss, fatigue, cytopenias, etc due to its effect on normal body cells apart from cancerous cells.
Targeted drugs are designed to target a specific gene or protein characteristic of the lung cancer cells. With the advancement in diagnostic techniques, a number of genetic abnormalities for NSCLC have been identified that can be targeted with the help of targeted drugs. Molecular testing to confirm the genetic abnormality is the pre-requisite for starting a targeted therapy.
Immunotherapy is a broad category of cancer therapy which includes various agents that enhance the capability of the immune system to fight against cancerous cells. Immune checkoint inhibitors used for lung cancer treatment are nivolumab, pembrolizumab, atezolizumab and durvalumab.
Treatment of SCLC (SMALL CELL LUNG CANCER)
Similar to NSCLC, the treatment for SCLC depends on the stage assigned to the disease with the help of the investigational tests. Very few patients are diagnosed with Stage I SCLC who can be considered the candidates for surgical resection. Thus, chemotherapy with or without radiotherapy remains the mainstay of the treatment. Preferred treatment approaches for different stages of SCLC:
Chemotherapy with or without radiotherapy is the preferred treatment for the limited-stage SCLC. Surgery may be employed for an early-stage disease, but chemotherapy with or without radiotherapy is generally recommended after surgery due to a high recurrence rate of SCLC. Prophylactic cranial irradiation may also be employed to prevent the spread of disease to the brain as per physician’s discretion.
Chemotherapy with or without radiotherapy is the preferred treatment for the extensive-stage SCLC. Radiation therapy is usually employed for the disease spread to distant organs not directly benefitted from chemotherapy. Prophylactic cranial irradiation may also be employed to prevent the spread of disease to the brain as per physician’s discretion.
Brief description of various treatment modalities employed for SCLC:
Chemotherapy means treatment with anti-cancer drugs that kill or decrease the growth of rapidly growing cancer cells. Chemotherapy is the mainstay of treatment for SCLC.
Radiotherapy is commonly combined with chemotherapy for the treatment of SCLC. Radiotherapy is also employed for the treatment of cancer spread to distant body parts including the brain. Whole brain radiation treatment is generally given to patients with spread of disease to the brain or to patients who are at higher risk of disease spread to the brain. Radiotherapy can also be used for palliation of symptoms of the disease such as pain, bleeding, and obstructive problems.