What Is Stage 1 Mesothelioma?

Stage 1 mesothelioma is the earliest of four stages that track the progression of mesothelioma and its spread throughout the body. In stage 1, cancer has not yet spread to distant tissues and organs, and the prognosis is better than in later stages.

Mesothelioma is caused by asbestos fibers that have been trapped in the lining of the lungs or other areas of the body. The presence of these fibers triggers an immune response that causes inflammation and scarring over long periods.

Chronic inflammation as a result of the asbestos fibers causes damage to tissues and DNA within the cells, leading to improper cellular replication and the formation of tumors.

Tumors that form in stage 1 mesothelioma have not spread through lymph nodes to other areas. Cancer remains localized to its origin either in the pleural lining of the lungs in pleural mesothelioma, the peritoneal lining of the abdominal cavity in peritoneal mesothelioma or elsewhere.

Characteristics of Stage 1 Mesothelioma

There are three staging systems for determining the progression of pleural mesothelioma, which have different definitions of stage 1. The most commonly used method is the TNM system.

The TNM classification system uses three factors to stage cancer: T describes the size of the original tumor, N describes the involvement of lymph nodes, and M describes metastasis (cancer spread).

There are two distinct classifications within stage 1 pleural mesothelioma:
  • Stage 1A: Small tumors have formed in one or both layers of the pleura, which is the tissue that lines the ribcage, diaphragm and outer portion of the lungs.
  • Stage 1B: Tumors have begun to invade tissue outside the pleura. Cancer may have invaded the mediastinal space between the lungs or the muscle tissue of the diaphragm.
Stage 1 mesothelioma tumor growth

More advanced tumor development within this stage may also include cancer progression into the chest wall or the pericardium, which is the outer covering of the heart. However, cancer has still not spread to nearby lymph nodes or distant sites of the body.

Cancer diagnosed at stage 1B is still considered stage 1 mesothelioma, and surgery typically remains an option.

Peritoneal mesothelioma does not utilize a formal staging system. Still, many physicians consider the disease early stage if it is confined to its original site of formation within the lining of the abdomen.

Stage 1 Mesothelioma Symptoms

Symptoms in stage 1 mesothelioma are typically mild or undetectable. When present, the symptoms of mesothelioma may be broad and mimic many other diseases.

First Signs of Mesothelioma

  • Pain
  • Persistent cough
  • Nausea
  • Shortness of breath
  • Fatigue
  • Weight loss
  • Insomnia

While pleural mesothelioma forms in the lining of the chest cavity and peritoneal mesothelioma develops in the lining of the abdominal cavity, the symptoms during early-stage mesothelioma may completely overlap, making diagnosis even more difficult.

Patients with early stage-mesothelioma often dismiss their symptoms as allergies or more common illnesses such as pneumonia or the flu.

Dyspnea, or difficulty breathing, in stage 1 mesothelioma is caused by the buildup of fluid between the two layers of the pleura. This disease process is known as pleural effusion and causes respiratory symptoms by increasing pressure on the lungs.

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Why Is Early-Stage Mesothelioma Difficult to Diagnose?

Stage 1 mesothelioma is often more difficult to detect than later stages due to its lack of specific or major symptoms. Stage 1 cases are often accidentally discovered after CT or X-ray radiology has been performed for an unrelated reason.

If a patient is aware of their history of asbestos exposure, early screening with the aid of a mesothelioma specialist can detect early-stage mesothelioma.

These symptoms, which are common between all types of early-stage mesothelioma, appear more often and with greater severity in later stages.

Prognosis for Stage 1 Mesothelioma

Patients have a better mesothelioma prognosis when compared to the cancer’s advanced stages.

If diagnosed at this stage, the two-year survival rate is between 41% and 46%. Surgery is more appropriate as a treatment at this stage than in later stages because the cancer is largely consolidated.

Aggressive treatment is more available, and a wider range of therapies are afforded in early-stage mesothelioma. Over 18% of patients diagnosed in stage 1 live for five years or more.

Due to having fewer symptoms and more treatment options, patients diagnosed with stage 1 mesothelioma have the longest life expectancy of patients with the disease.

In comparison, roughly 7% of patients diagnosed with stage 4 mesothelioma will survive for five years and the average life expectancy is around one year.

Cancer cell type ultimately determines diagnosis and treatment for stage 1 mesothelioma. The epithelioid mesothelioma cell type is easier to surgically remove, and patients have a better survival prognosis. About 60% of mesothelioma cases are epithelioid.

Fibrous sarcomatoid and biphasic (mixed) types are more aggressive forms of mesothelioma that do not often respond as well to treatment. These cases comprise about 40% of all mesothelioma patients.

Is There a Cure for Stage 1 Mesothelioma?

There is currently no cure for any stage of mesothelioma. The goal of most mesothelioma treatment is remission, which is the period when cancer has stopped growing. There is a greater chance of remission if mesothelioma is treated during stage 1, and surgery is the best treatment option at this stage.

Researchers are developing new therapies for mesothelioma through clinical research trials, which have allowed some mesothelioma survivors to outlive their life expectancies by several years.

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Stage 1 Mesothelioma Treatment Options


The most common and effective surgical options for stage 1 pleural mesothelioma are extrapleural pneumonectomy and pleurectomy with decortication.

Extrapleural pneumonectomy is an aggressive surgery that removes the entire affected lung, linings of the heart and lungs, nearby lymph nodes and a portion of the diaphragm.

The procedure offers the greatest chance of survival, but it can permanently reduce a patient’s safe activity levels.

Pleurectomy and decortication is a less aggressive alternative that removes the pleural lining of the lungs along with any visible tumors. The surface of the lung is then scraped to remove the remaining cancer cells. The lung is not removed.


Chemotherapy is often used in combination with surgery to treat stage 1 mesothelioma but may be prescribed on its own. Pemetrexed (Alimta) is used in combination with cisplatin as the most effective first-line treatment for mesothelioma.

Delivery of chemotherapy can occur before, during or after surgery with the intent of either shrinking the tumor before removal, exposing tumor cells directly during surgery, or killing the remainder of cancer cells after surgery.

The best treatment approach for early-stage peritoneal mesothelioma has been the hyperthermic intraperitoneal chemotherapy (HIPEC) procedure. This method involves washing the abdominal cavity with a heated chemotherapy solution for 60 to 90 minutes immediately after surgery.


Radiation therapy uses high-energy beams to kill cancer cells in a specific and discrete location while minimizing damage to neighboring healthy tissue.

Radiotherapy is often used to alleviate pain and other symptoms of tumors that have caused excess pressure on the lungs or other organs. For this reason, radiation therapy is not often used alone in the treatment of stage 1 mesothelioma but is combined with other therapies.

External beam radiation therapy has shown effectiveness in pleural mesothelioma patients with its ability to conform to the shape of the tumor and specifically modulate the dose. Treatments are fast and painless. The most common side effect is skin irritation.

Clinical Trials

Patients with stage 1 mesothelioma often qualify for clinical research trials due to their lack of symptoms and general health.

Developing treatments that are undergoing research in clinical trials are not yet approved for mass-market use. However, these studies allow patients the opportunity for otherwise unavailable and potentially effective therapies.

The following are examples of clinical research trials offered to early-stage mesothelioma patients:
  • Vaccine therapy
  • Immunotherapy
  • Virus therapy
  • Gene therapy
  • Photodynamic therapy

Patients diagnosed with stage 1 mesothelioma have cause for hope thanks to more treatment options than any other stage, a better prognosis and a longer life expectancy.
Some early-stage patients are now able to live free of cancer and offer inspiration to those with a new diagnosis of mesothelioma.