What Is Stage 3 Lung Cancer?

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Stage 3 non-small cell lung cancer (NSCLC) is lung cancer that has spread to nearby (regional) tissues. Stage 3 also has three sub-stages that give more details about how and where the cancer has advanced.

As with most types of lung cancer, symptoms of stage 3 NSCLC—such as a chronic cough or shortness of breath—can easily be confused for less serious conditions. For that reason, around 35% of people with lung cancer have stage 3 disease at the time of diagnosis.

This article discusses the causes of stage 3 NSCLC and how it is diagnosed. Learn more about the symptoms and treatment options involved with stage 3 NSCLC below.

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An Overview of Staging For Non-Small Cell Lung Cancer

Staging

Stage 3 lung cancer is generally defined as cancer that has spread to areas near the primary (original) tumor. This stage is broken up into three substages: stage 3A, stage 3B, and stage 3C, which differ by how far and how much the cancer has spread.

Oncologists use a classification system called the TNM system to characterize the stages of lung cancer. T refers to tumor size, N refers to lymph node involvement, and M represents spread (metastasis).

The most current version of this system, called TNM 8, describes the stage of cancer using alphanumeric codes.

Stage 3A lung cancer is described as:

  • T1N2M0: The tumor is less than 3 centimeters (cm) in size and has spread to lymph nodes farther away but on the same side of the body as the tumor.
  • T2N2M0: The tumor is larger than 3 cm but less than 5 cm and has spread to lymph nodes farther away but on the same side of the body.
  • T3N1M0: The tumor is larger than 5 cm or has spread locally to an area like the chest wall or pericardium; nearby lymph nodes are affected.
  • T3N2M0: The tumor is any size but is near an airway or has spread locally to an area like the chest wall or diaphragm; lymph nodes that are further away but on the same side of the body are affected.
  • T4N0M0: The tumor is larger than 7 cm or has spread locally to an area like the mediastinum or the diaphragm, but no lymph nodes are affected.
  • T4N1M0: The tumor is larger than 7 cm or has spread locally to an area like the mediastinum or the diaphragm; lymph nodes that are farther away but on the same side of the body are affected.

Stage 3B is described as:

  • Any T, N3, M0: A tumor of any size that has spread to lymph nodes on the other side of the chest from the tumor or to nodes near the collarbone or neck muscles; distant regions of the body are not affected.
  • T3 or T4N2M0: The tumor has spread to nodes farther away but on the same side of the chest (N2 nodes) and it is either large (>5 cm) or has invaded local structures.

Stage 3C is described as:

  • T3N3M0: The tumor is between 5 cm and 7 cm across. It has grown into the chest wall lining or the tissues surrounding the heart, or there are at least two separate tumors in one lobe of the affected lung. Distant regions of the body are not affected.
  • T4N3M0: The tumor is either larger than 7 cm, there are at least two tumors in different lobes of the affected lung, or the tumor has grown into nearby areas like the trachea or esophagus. Distant regions of the body are not affected.

Tumors involving a malignant pleural effusion (fluid build-up containing cancer cells in the pleural cavity between the layers lining the lungs) were changed from stage 3B to stage 4 in 2009.

Stage 3 Lung Cancer Symptoms

Stage 3 lung cancer symptoms are variable because of the wide spectrum of possibilities the stage encompasses.

General lung cancer symptoms are common and include:

Beyond that, the specific location of the cancer and related issues can give rise to other symptoms. For example:

  • Cancer that has spread to areas such as the chest wall and diaphragm can result in pain in the chest, ribs, shoulders, and back.
  • Tumors located near the airways can cause hemoptysis (coughing up blood) and wheezing.
  • When the tumor involves areas such as the esophagus and other chest structures, dysphagia (difficulty swallowing) and hoarseness can occur.
  • Pain in the back, chest, and ribs is common if pleural effusion is present, and this can result in increasing shortness of breath.

Symptoms of any cancer, such as fatigue and unintentional weight loss, may be present as well.

Doctor taking heartbeats of sick patient
jacoblund / Getty Images

Treatment

The treatment of stage 3 lung cancer is the most controversial of all lung cancer stages. Here too, this is partly because this group of malignancies is so varied.

Stage 3 lung cancers have a poor survival rate. Because of that, the National Cancer Institute (NCI) states that everyone with stage 3 lung cancer be considered a candidate for clinical trials—studies that evaluate new treatments or combinations of treatments for lung cancer.

For people that are relatively healthy, a combination of chemotherapy or chemotherapy and radiation therapy is often recommended. If individuals are unable to tolerate chemotherapy, radiation therapy can be used alone to treat symptoms such as pain and shortness of breath.

Targeted Therapy

It's now recommended that molecular profiling (gene testing) be done for everyone with NSCLC, especially lung adenocarcinoma. This can reveal mutations that may be treatable.

Medications have been approved for people with mutations such as EGFR mutations, ALK rearrangements, ROS1 rearrangements, KRAS mutations, and other less common genetic alterations. Such drugs, known as targeted therapies, can sometimes result in excellent control of the disease.

Resistance often develops over time, but next-generation medications are currently approved and being tested in clinical trials for when this occurs. For those with squamous cell carcinoma of the lungs, anti-EGFR antibodies may be used.

Clinical trials are also studying medications that address other genetic changes in lung cancer.

Immunotherapy

Five immunotherapy drugs have been approved for the treatment of lung cancer. These medications work by enhancing the ability of the body's own immune system to fight cancer.

While the drugs do not work for everyone, some people have achieved long-term, disease-free control of their cancer.

Imfinzi (durvalumab), approved by the Food and Drug Administration (FDA) in February 2018, is an immunotherapeutic drug used to treat inoperable stage 3 lung cancer after chemotherapy and radiation therapy have failed to control progression. When used in this setting, it was found to significantly improve progression-free survival.

Surgery

Surgery offers a chance for a cure, but it is not always possible with tumors of this size.

When surgery is done to remove a stage 3A tumor, it is usually followed up with adjuvant chemotherapy (chemotherapy after surgery to kill any remaining cancer cells).

Still, the risk of cancer recurrence after surgery is fairly high for people with stage 3A lung cancer.

Stage 3B Treatment

As with stage 3A, 3B cancers may be treated with chemotherapy, radiation therapy, targeted therapies, and immunotherapy.

Stage 3B cancers cannot usually be treated with surgery and are considered inoperable. However, in some cases, the use of chemotherapy and radiation is able to decrease the size of a tumor so that surgery is then possible. This is known as neoadjuvant therapy.

For people with stage 3 lung cancer, treatments can also be used for palliative purposes. Here, the focus of treatment is relieving symptoms such as pain and shortness of breath, rather than trying to control the malignancy.

In some cases, palliative therapy might actually improve survival for people with stage 3 lung cancer.

Prognosis

The overall five-year survival rates for stage 3A and 3B lung cancer are 36% and 26%, respectively, but they can vary widely. The five-year survival rate for stage 3C lung cancer is less promising at 13%. 

It's important, however, to keep in mind that these statistics are based on how people did with lung cancer in the past. Since there have been more medications approved for the treatment of lung cancer in the last decade than during the four decades preceding it, these statistics are fairly unreliable in estimating actual life expectancy.

Prognosis is a prediction. An estimate. An open conversation with your doctor about your specific case and what the prognosis can and cannot tell you can be helpful in putting this in perspective.

Coping

Studies suggest that learning what you can about your cancer helps with the outcome.Ask questions. Involve your loved ones and encourage them to ask questions as well. Consider joining a support group. Learn about clinical trials that might be appropriate for your particular situation.

Learning about your cancer and going through treatment can take a tremendous amount of time. Ask for and allow your loved ones and friends to help and encourage you in your journey. Don’t lose hope—even if that hope is only to be as comfortable as possible while you enjoy the company of your loved ones.

A Word From Verywell

If you have a constellation of certain risk factors, you may be eligible for screening for lung cancer that may catch the disease well before it reaches stage 3. Screening with an annual low-dose computed tomography (CT) chest scan is recommended for people between ages 50 and 80 who have a 20 pack-year smoking history and currently smoke or have quit smoking within the past 15 years.

According to the American Lung Institute, 8 million Americans are considered at high risk of lung cancer. If only half of these individuals were screened, over 12,000 lung cancer deaths could be avoided. If you meet all of the screening criteria, talk to your doctor.

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