Mesothelioma treatment is tailored uniquely for each individual patient. Often the stage of the malignant mesothelioma at diagnosis dictates treatment options. Staging of a particular disease also helps the medical team in not only planning treatment but also in prognosis estimation as well as in the identification of existing clinical trials that the patient may be eligible for. Three systems of staging are currently being used for pleural mesothelioma. None is being used for peritoneal mesothelioma.
Knowledge of how a particular cancer develops is pertinent to the process of staging. Certain staging systems cover only a specific cancer while others can be used to cover a variety of types. Some common elements are found in most staging systems, namely, location of the primary tumor, size of tumor, number of tumors, lymph node involvement, histology type, grade of tumor and presence of metastasis.
To determine accurately the stage of any cancer, physicians usually rely on a variety of techniques. These include physical examinations, imaging techniques including roentgenograms, CT scans, MRIs, and PET scans. Examination of the patient’s blood, urine, serum and biopsy of tissues may also provide helpful clues. Tumor markers may also be used. Pathology reports are very helpful in providing information about the exact size of the tumor, the tumor’s extension into neighboring structures, and the tumor’s histology and grade. Surgical reports also render aid to staging.
The most common cancer staging system being used for mesothelioma is the TNM (primary tumor, regional lymph nodes, distant metastases) system. Stage I is assigned when the mesothelioma only involves pleura, ipsilateral lung, ipsilateral pericardium, and ipsilateral diaphragm. Lymph nodes are unaffected. Stage II is assigned when the mesothelioma has already involved the nearby hilar lymph nodes on the contralateral side. The lung, pericardium, or diaphragm on the contralateral side may also be involved. Stage III is assigned when the mesothelioma has spread to involve the chest wall, soft tissues, ribs, heart, esophagus and/or other organs in the chest cavity in the ipsilateral side. Lymph nodes may or may have not spread to the lymph nodes on the same side as the primary tumor. Stage IV is assigned when the disease has either already spread into the lymph nodes of the chest on the contralateral side of the primary tumor, extended to the contralateral pleura, or have extended to the organs in the abdominal cavity or neck. Presence of distant metastases is considered Stage IV.
The Butchart System is the oldest staging system for cancers. It is also the most commonly used system of staging for all types of cancer. The extent of the primary tumor mass is the main basis of this system. Stage I is assigned when mesothelioma is located in either pleura, or on the ipsilateral diaphragm. Stage II is assigned when the mesothelioma has spread into the chest wall, esophagus, heart or pleura on both sides. The lymph nodes in the chest may also be affected. Stage III is assigned when the mesothelioma has invaded the diaphragm and has reached the peritoneum. Lymph nodes outside the chest may also be involved. Stage IV is assigned when there is evidence of distant metastases.
The Brigham System is the latest system to be developed. Resectability and lymph node involvement is the basis of this system. Stage I is assigned when mesothelioma is still resectable, with no lymph node involvement. Stage II is assigned when mesothelioma is resectable but lymph nodes are involved. Stage III is assigned when the mesothelioma is unresectable, has spread to neighboring chest structures, and may or may not have extrathoracic lymph node involvement. Stage IV is assigned when there are distant metastases.
Information gleaned from these staging systems must be disclosed to patients. Patients reserve the right to know the exact state of their disease and all parties involved will benefit greatly when such disclosure is made.