Surgery for Lung Cancer Patients

The first important decision about surgery is choosing when to operate and when not to operate, because not everyone with lung cancer will benefit from surgery. There are two categories of lung cancer: small cell lung cancer and non-small cell lung cancer (Figure 1). Surgery is not usually used to treat people with small cell lung cancer. Most of this chapter will discuss non-small cell lung cancer.

Surgery for Non-Small Cell Lung Cancer
Non-small cell lung cancer includes several different subtypes (Figure 1), but the treatment for all these subtypes is similar. After a person is diagnosed with non-small cell lung cancer, the decision to proceed with surgery is based on two factors: (1) the stage of the cancer and (2) the ability of the patient to function without the cancerous portion of lung. We will discuss these two factors in the next two sections of this chapter.

Figure 1:  Lung Cancer, as seen through the microscope

Images courtesy of Jey-Hsin Chen, MD, PhD

Figure 1: A: Small cell carcinoma. B: Squamous cell carcinoma. C: Adenocarcinoma. D: Adenocarcinoma with lepidic features. B, C, and D are all different types of non-small cell lung cancer.

Lung Cancer Staging from the Surgeon’s Perspective
After a diagnosis of lung cancer has been made, the most important question is, “How far has it spread?”  This process is called staging. This is first determined by using imaging tests such as a positron emission tomography (PET) scan and/or a computed tomography (CT) scan.  From these tests the surgeon can determine the location of the cancer and whether the cancer is confined to the lung or has spread to other areas in the body such as lymph nodes, the other lung, the brain, or other organs. These findings allow the surgeon to classify the cancer into one of four groups called “stage” (stage I, stage II, stage III, stage IV).

Usually the combination of chest computed tomography scan (CT) and positron emission tomography (PET) are enough to determine the location and dimension of the lung cancer and whether it has already spread to other areas of the body as the lymph nodes, the liver, the bones and the adrenal glands. However, if there is concern on the PET scan that lymph nodes may be involved, the surgeon usually will order a magnetic resonance imaging (MRI) to assess whether cancer is present in the brain.

Even though the PET, CT and brain MRI are very good at detecting the spread of lung cancer to the liver, the bones, the adrenal glands and the brain, there is an 8-10% chance of missing cancer in the lymph nodes in the center of the chest (Figure 2: the mediastinum). Since determining the presence of cancer in the mediastinal lymph nodes is necessary to define the cancer stage, it is important to know more definitely whether the cancer involves the mediastinal lymph nodes. Therefore, a biopsy (a small tissue sample) of the mediastinal lymph nodes is usually recommended before lung cancer surgery.

Mediastinal lymph nodes may be biopsied in several different ways. The two most common ways are (1) with a bronchoscope (a flexible camera that is inserted through the windpipe) and ultrasound imaging guiding a small needle or (2) an operation (mediastinoscopy). During mediastinoscopy, a surgeon makes a small incision in the neck just above the breastbone and puts a camera behind the breastbone to take tissue samples of the mediastinal lymph nodes around the windpipe. (Figure 3)

Figure 2: Mediastinum

Illustration by Alexandra Hunt, MD

Figure 2: The green-shaded area is the mediastinum. Purple dots around the airways are the mediastinal lymph nodes.

Figure 3:  Mediastinoscopy

Illustration by Alexandra Hunt, MD

Figure 3:  Mediastinoscopy: a scope and instruments are used to sample the mediastinal lymph nodes.

If the biopsy of the mediastinal lymph nodes shows no cancer, then we presume the patient to be in stage I or II and recommend surgical removal of the lung cancer. However, if there are cancer cells in these lymph nodes, chemotherapy with or without radiation therapy usually is the first treatment, sometimes followed by surgery.

The importance of defining the cancer stage is due to the fact that lung cancer at different stages requires different treatment (Table 1). Surgery has a potentially curative role in non-small cell lung cancers that are stages I to III (Table 1) and in selected cases of stage IV lung cancer.

Table 1.  Treatment of Lung Cancer by Stage¹
 

Surgery usually is the first step in the treatment of Stage I and II non-small cell lung cancers. In Stage III cancers, chemotherapy with or without radiation therapy is given first and surgery follows if it will potentially be beneficial. The distinguishing feature between stages I, II, and III is the involvement of lymph nodes with cancer. In stage I, cancer has not spread to the lymph nodes. In stage II, the lymph nodes that are involved are located within the section of lung being removed. In stage III, the lymph nodes involved are outside of the lung and organized around the main airway in the center of the chest, in the area of the body called the mediastinum (Figure 2). When the cancer has spread to the lymph nodes in the mediastinum, surgery alone is not enough. In this case, studies have shown that chemotherapy with or without radiation therapy, sometimes combined with surgery, has a better outcome than surgery alone.

Surgery in Stage IV Lung Cancer
If cancer has spread to distant sites, it may not be possible or beneficial to remove all the cancer with surgery. Additionally, if the cancer invades structures that cannot be removed (for example, the heart), then surgery may not be appropriate as primary treatment. However, there can be a role for surgery in widespread cancer if surgery will help relieve some of the symptoms caused by the cancer. If the cancer is blocking an airway, a limited procedure might be done to unplug the airway. When advanced cancer blocks the lymph channels draining the space around the lung, fluid can build up in this space. Surgery may be required to drain this space and re-expand the lung to relieve the symptoms associated with the fluid. However, most surgery for lung cancer is done for limited disease (lower stages), usually with the goal of curing the cancer. Occasionally, stage IV cancer that has spread to only a single location outside of the lung such as the brain or adrenal gland may be a candidate for surgical treatment of both the metastasis (the single cancer location outside of the lung) and the primary lung cancer. This special situation should be discussed with the cancer team (the surgeon, the oncologist and the radiation oncologist).

Even if lung cancer can be removed based on the results of the staging tests, not every person can have part of their lung removed and return safely to their normal life outside the hospital. Every operation has risks, and one of the difficult aspects of surgery is choosing which people will do well after surgery and which people will have difficulty recovering from surgery. Surgeons use many different tests to help predict which patient can undergo surgery safely and be able to live with fewer lung after surgery.

The most important test we use to decide when to operate is the simplest: a thorough history and physical examination. The surgeon asks questions about the patient’s current state of health and past medical history, and performs a physical examination to make sure the patient is prepared for the operation.

Problem areas that come up during the history and physical examination may be evaluated with more testing. There are two major issues to consider preoperatively: to make sure that the patient is healthy enough to safely have surgery, and to find any other health problems that can be improved before the operation. For example, diabetes should be well controlled before surgery since it impacts wound healing. It is also very important to stop smoking before lung surgery in order to reduce the risk of respiratory complications after surgery. See Chapter 11: How to Quit Smoking Confidently and Successfully. After dealing with each person’s individual health problems, the preoperative workup for lung surgery focuses on the lungs and the heart in order to evaluate the performance of these two organs.

Lung and Heart Function
Surgery for lung cancer usually involves removing part of a person’s lung. Therefore, it is important to be sure that the person will be left with enough functioning lung after surgery to provide oxygen to, and eliminate carbon dioxide from, the body. A simple test such as climbing stairs or walking as far as possible in six minutes may be used to give an overall idea of heart and lung fitness, but more detailed testing usually is required before lung surgery.

The tests most commonly used to evaluate the lungs before surgery are called pulmonary function tests. These tests check the lung volumes, air flows, and gas exchange capabilities. They give a baseline measure of lung function and help predict whether the lungs will be able to do their job adequately after part of the lung is removed during surgery. The tests are designed to measure how much air can be moved in and out of the lungs, and how quickly gases diffuse from the lungs into the blood. The tests involve breathing through a machine which measures air flow, and inhaling a marker gas (a very small amount of carbon monoxide) to test how quickly that gas is removed from the air in the lungs. It is important to stop smoking before the pulmonary function test, because blood levels of carbon monoxide are elevated after smoking and this can interfere with the test. Medication may be given during the test to determine whether lung function can be improved with medication.

If a person’s pulmonary function tests show limited lung function, then a quantitative ventilation/ perfusion scan (QV/Q scan) is used to determine how much air and blood flow go to each section of the lung. This allows the surgeon to calculate how much lung function will remain after the section of lung containing the cancer is removed, thus predicting how the person will respond to surgery. If concerns remain after the QV/Q test, the patient may be asked to have other testing, including exercise tests and blood tests. The purpose of all the lung function tests is to predict whether there will be enough lung function remaining to allow the patient to return to normal life after surgical removal of the part of the lung with the cancer.

Often it is also necessary to evaluate the patient’s heart before lung surgery because the risk factors for heart disease are often present in patients who develop lung cancer. Furthermore, surgery places the body under stress. The body mobilizes every resource available to heal after surgery, and this effort can place major stress on the heart, especially when an entire lung has been removed (pneumonectomy). Therefore, it is important to check that the heart is functioning adequately before performing an operation. In some cases, a history and physical examination can provide enough information to reassure the treatment team that the heart will be able to safely power the body through the stress of surgery. If further testing is required, it may be simply an electrocardiogram (ECG). Another test that might help predict how the heart will respond to the stress of surgery is a stress test, in which stress is placed on the heart by walking on a treadmill or by injecting a medication that stresses the heart. Imaging of the heart may include an ultrasound test or a scan. If any problems with the heart are found during testing, additional procedures or medicines may be required to make sure the heart is as ready as possible before surgery.

Alternatives to Surgery
If surgery is not recommended after the staging workup and heart and lung testing, there are several alternative treatments available. These treatments also may be used before or after surgery, to give the best chance that cancer will not spread to other parts of the body or recur in the lungs after treatment. Radiation therapy can be used to kill cancer cells in a particular part of the body. The radiation is focused at the known or suspected location of the cancer. New highly-focused radiation techniques allow maximum doses of radiation to be delivered precisely to the cancer, killing the cancer while sparing as much normal tissue as possible. In some people with stage I or II cancers with poor lung function, focused radiation may be recommended instead of surgery. Chemotherapy medicines, given either intravenously or as pills, kill cancer cells throughout the body. Chemotherapy medicines spread through the entire body, and they can kill cancer cells that haven’t been discovered or are too small to show up on imaging.

Surgery for Small Cell Lung Cancer
Small cell lung cancer is very different from non-small cell lung cancer. Small cell lung cancer tends to spread more quickly than non-small cell cancer, and surgery alone has a very small chance of curing small cell lung cancer, even in the early stages. Chemotherapy and radiation are the primary treatments for most small cell lung cancers. However, surgery may benefit a small group of patients with early small cell lung cancer, used in combination with chemotherapy, with or without radiation therapy. Surgical sampling of the lymph nodes from the middle of the chest is also part of the staging workup of small cell lung cancer if surgery is contemplated. See Chapter 1: Diagnosis and Staging of Lung Cancer and Chapter 5: Treatment for Small Cell Lung Cancer.

Various approaches may be used to remove lung cancer. The most common approach is an incision between the ribs to access the lung and surrounding lymph nodes (Figure 4a). This incision (a thoracotomy) wraps around the side of the chest, parallel with the ribs, and allows the surgeon direct access to the lungs and the other contents of the chest.

Figure 4a:  Thoracotomy: the blue line corresponds to the chest incision

Illustration by Alexandra Hunt, MD

To limit the pain and shorten the recovery after surgery, sometimes it is possible to do surgery without performing a full thoracotomy. One way to do this is to use a video camera that goes into the chest through a small incision, combined with instruments that enter the chest through other small incisions. This type of surgery is called video-assisted thoracic surgery (VATS) (Figure 4b). A further refinement of VATS is to mount the instruments to a robot (Figure 4c), which allows very precise control when manipulating the lung and delicate surrounding tissues. However, it is important to be aware that even if the surgeon plans to do the operation using the VATS approach or the robot, sometimes it is necessary to convert during the operation to a bigger incision (thoracotomy).

Figure 4b:  Video-Assisted Thoracic Surgery (VATS) and robotic thoracic surgery incisions: the blue lines correspond to the chest incisions.

Illustration by Alexandra Hunt, MD

Figure 4c:  Robotic thoracic surgery

Illustration by Alexandra Hunt, MD

Besides deciding on which approach will be used to remove the portion of lung containing the cancer, a surgeon must decide exactly what to remove. The first priority is to remove the cancer. It is important to remove some normal surrounding lung along with the cancer, because there are microscopic extensions of the cancer that can grow and cause cancer recurrence if they are not removed. The most common surgery for lung cancer removes the entire lobe containing the cancer, together with the lymph nodes inside the lobe (lobectomy, Figure 5a). Removing the entire lobe allows the best possibility for long term survival.² However, recent studies have been evaluating whether the resection of the cancer within a smaller part of the lung (segmentectomy) has the same results, in term of survival and probability of cancer recurrence that occur when removing the entire lobe (lobectomy). The results of these studies will be available in the next years.

In patients where there will not be enough healthy lung left after an entire lobe is removed, the surgeon may decide to remove just the tumor with a small amount of surround lung called a (wedge resection) or a segment of lung (segmentectomy) that contains the cancer (Figure 5b). If the tumor is too close to the center of the chest, or if the main airways of the lung are involved, sometimes it may be necessary to remove the entire lung that is affected by cancer (pneumonectomy, Figure 5c). Airways may be divided and sewn back together (“sleeve resection”), if this allows complete removal of the cancer without removing as much healthy lung tissue (Figure 5d). In addition to removing the part of the lung that is affected by the cancer, lung cancer surgeons remove lymph nodes in the chest at the time of lung surgery, to evaluate whether the cancer has spread to these lymph nodes.

Figures 5a-d: Types of Resection

Illustrations by Alexandra Hunt, MD

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