What Is Stage 1 Mesothelioma?

As with other forms of cancer, stage 1 mesothelioma is the least advanced stage and often carries the best prognosis. At this stage, the tumors are localized, meaning they haven’t spread to other parts of the body.

When caught early, this type of cancer can be treated with a multimodal plan of surgery, chemotherapy, radiation, or immunotherapy. Although there’s no cure, doctors can remove the majority of cancerous cells through resection (surgery to remove the tumors), as well as prevent the growth of new ones. Life expectancy, when treated, can span from 21–40 months.

Unfortunately, mesothelioma is seldom diagnosed in stage 1. This is mainly due to the fact that symptoms do not present themselves until the disease has already begun to spread throughout the body. Even when symptoms are present, they can mirror those of less severe conditions like pneumonia. In the secluded instances when it’s caught early, it’s usually by accident and the patient is being examined for another reason.

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By Type

Details surrounding stages can differ depending on their location in the body.

This is an image of a lung with stage 1 cancer.

Stage 1 Pleural Mesothelioma

This cancer is staged like many other cancers on a 1 through 4 scale. For pleural mesothelioma cases, doctors use one of three staging systems — the Butchart system, the Brigham system, or the TNM system.

The TNM system is recommended when staging pleural mesothelioma. T refers to the size of the primary tumor, N refers to the number of affected nearby lymph nodes, and M refers to the extent of metastasis (spread).

Stage 1A

  • Found in the inner lining of the chest wall (the pleura)
  • Localized on one side of the chest
  • Cancer cells found in the tissue covering the lungs, the area between the lungs (the mediastinum), and the top of the diaphragm

Stage 1B

  • Found in the inner lining of the chest wall and in the tissues covering the lung, the mediastinum, and the top of the diaphragm on a single side of the chest
  • Cancer has begun spreading into the diaphragm, lung tissue, tissues between the ribs, soft tissues in the chest wall, and the sac around the heart

This is an image of stage 1 peritoneal mesothelioma.

Stage 1 Peritoneal Mesothelioma

Of the approximately 3,300 cases of this disease diagnosed per year, only about 660 cases occur in the peritoneum. Due to the rarity of this form of the disease, there is not an established staging system for peritoneal mesothelioma. Doctors typically use the American Joint Committee on Cancer (AJCC) 1 through 4 staging scale or the Peritoneal Cancer Index (PCI) when diagnosing this type of disease.

PCI has become the preferred method for staging peritoneal mesothelioma. It scores the extent and spread of the cancer on a 0 through 39 range. A patient’s PCI can help doctors assess whether or not they are eligible for treatment. Lower scores typically exhibited in stage 1 mesothelioma indicate less aggressive cancer, smaller tumors, and an overall better prognosis. Patients with low PCI scores tend to be candidates for invasive treatments. At stage 1, the PCI ranges between 1 and 10.

This is an image of stage 1 pericardial mesothelioma.

Stage 1 Pericardial Mesothelioma

When tumors develop on the lining of the heart sac,  it’s called pericardial mesothelioma. This is extremely rare, accounting for less than 5 percent of all cases. As a result, there is not a formal staging system for this form of the disease. Doctors can use the AJCC staging scale; however, because the pericardial form is so aggressive, it is often diagnosed in advanced stages or after the patient has passed away.


As with other aggressive cancers, patients with stage 1 mesothelioma typically exhibit few or no symptoms. It is for this reason that most patients go undiagnosed at this stage. When symptoms do manifest, they may be mistaken for other conditions, such as pneumonia or the flu.

Stage 1 symptoms can include:

  • A persistent cough
  • Body aches
  • Chest pain
  • Fatigue
  • Fever
  • Shortness of breath (dyspnea)

Survival Rates

Survival rates for any form of cancer are calculated using statistics from other patients with the same or similar conditions. The rate demonstrates how long other patients have typically survived after their diagnosis.

Patients with stage 1 mesothelioma who receive treatment generally have a survival rate between 21 and 40 months. However, because this is illness is scarce, research is scarce and every case is unique. Survival rates also vary by histologic subtypes. Some genetic factors may alter the overall prognosis of the patients. Improved treatment options have also correlated to improved survival rates.

Treatment Options

Doctors typically treat stage 1 with a multimodal treatment plan that includes a combination of surgery, chemotherapy, radiation, and immunotherapy. While stage 1 patients generally have the greatest range of treatment options, they must be healthy enough to undergo a radical treatment plan.

Patients may also be eligible for clinical trials. Researchers hold clinical trials as a means to test new treatments and emerging drugs. Talk to your doctor about whether clinical trials are a good solution for you.

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