Advances in diagnostic technologies and treatment-related procedures for mesothelioma patients have led to enhanced survival times for a number of different patient classes. These advances have allowed physicians to diagnose the disease sooner than they’ve previously been able to diagnose it, which allows treatments for mesothelioma to begin at an earlier time as well. However, not all patients are eligible for these new procedures and most still receive a diagnosis in the disease’s later stages when radical surgery is not an option. Because of this, research into pleural mesothelioma and peritoneal mesothelioma continues on a number of important fronts.

A series of articles on mesothelioma have recently been published in Current Treatment Options in Oncology, an important medical journal that features expert commentary on contemporary treatment practices for a number of different cancers. One of these recent articles is a report on the diagnosis, staging and surgical treatment of pleural mesothelioma. The article describes the current thinking on these topics and provides a detailed overview of the current mesothelioma staging system.

Overview of the Article

The article is divided into three basic sections: Diagnosis, Staging and Surgical Management. The section on mesothelioma diagnosis describes the “clinical and radiological presentation” of the disease, as well as some of the steps and procedures involved with pathology analysis. The section on staging describes, in detail, the current staging system used for pleural mesothelioma patients. The final section describes various treatment protocols featuring surgical intervention.

Mesothelioma Diagnosis

When the disease is in its earliest stages, the results of physical examinations are “non-specific,” but they quickly become more serious as the disease progresses. CT (computed tomography) scans are the preferred imaging modality for most cases of mesothelioma. MRI features enhanced resolution and soft-tissue contrast over CT, but for basic diagnostic purposes the images provided by CT are more than adequate. CT’s principal failing is poor presentation of chest wall involvement and tumor infiltration of certain pleural structures, so MRI may be indicated for these particular purposes, but CT is adequate for most cases of preoperative staging.

The article also discusses a study conducted by Dr. Harvey I. Pass that showed how three-dimensional CT imaging can be used to conduct pre-operative tumor volume analysis. Dr. Pass found that CT was able to measure tumor bulk and to predict survival times among patients with different levels of tumor volume, so CT is said to have both diagnostic value and prognostic value.

Another common imaging system in mesothelioma diagnosis is PET (positron emission tomography). PET is an important diagnostic modality because it specializes in the identification of distant metastases, something that CT is simply unable to do. Because radical surgery requires patients to be in the best overall health, any evidence of distant tumor seeding is a negative indicator for this kind of procedure. Even as staging is PET’s primary function in mesothelioma treatments, there is evidence that indicates PET can also be used to predict median survival in some patients.

Imaging technologies are the standard non-invasive diagnostic procedures, but a definitive diagnosis requires pathology assessment. The most common procedures that physicians deploy for sample extraction and analysis are thoracentesis, thoracoscopy and VATS. Due to its highly invasive nature, thoracotomy is not indicated for exploratory surgery.

When the sample has been removed, a pathologist must examine the specimen for malignant indications. Immunohistochemistry analysis is the standard testing methodology to determine a diagnosis. Because no single marker is 100% positive for mesothelioma, most of these analyses test against a panel of antibodies and use a combination of positive stainings and negative findings to determine a complete diagnosis.

For more information, please read mesothelioma diagnosis.

Mesothelioma Staging

A variety of staging systems have been proposed for mesothelioma, but all of them have had some notable downsides. The current system in use was developed by the International Mesothelioma Staging Systems group and is a 4-stage system that is based on a TNM model that represents an individual’s present state of tumor spread (T), lymph node status (N) and existence of metastases (M). Within each of these designations, there are individual status designations and the final staging decision is based on combining the statuses of each of the constituent models. The T value measures the extent of tumor bulk and spread, and has 5 possible values: T1a, T1b, T2, T3, T4, with T1a the best case scenario for mesothelioma patients, meaning limited tumor bulk, with no involvement of the visceral pleura. The N status has 4 possible values: N0-N3, again with N0 the best case, meaning no lymph node involvement. The M status is a value of 0 or 1, meaning no distant metastases or any evidence of distant metastases.

These designations are then put together to determine an individual patient’s current stage. The staging system is as follows:

For more information, please read: mesothelioma stages.

Surgical Management of Mesothelioma

Most patients who are diagnosed with mesothelioma receive a diagnosis later in life. Because of this, accurate staging of patients is an important element in developing a treatment plan, especially a plan that can include surgery. Older patients are less likely to tolerate the invasive surgery and extensive recovery associated with mesothelioma surgeries. Patients with no evidence of metastases and limited tumor involvement are the target patients for surgical intervention and multimodal therapy. Those with M1 status are immediately not considered for radical surgery. For patients who are between the best and worse cases though, a judgment call must me made by their physicians as to appropriate an treatment course.

Multimodal protocols featuring surgery, chemotherapy and localized radiotherapy remain the best way to extend median survival for eligible patients, but there is still much research being conducted on which combination of modes is the most effective in treating mesothelioma, so definitive statements on treatment methods are not yet possible. The role of pleurectomy/decortication vs. extrapleural pneumonectomy is one of the most controversial questions among mesothelioma physicians. A number of studies have been done, but the choice often comes down to the choice of individual surgeons. There are a number of other controversial questions as well, such as the the question of whether chemotherapy should be deployed in an adjuvant or a neoadjuvant manner for greatest treatment efficacy.

For more information on mesothelioma treatments, please read: Mesothelioma Treatments: Surgery and Mesothelioma Treatments: Chemotherapy and Radiation.

Conclusion

Even as research as improved the efficacy of our treatments, mesothelioma still remains one of the most difficult of all cancers to treat effectively. The work that is currently being conducted by physicians and researchers is an important step in changing the dynamics of mesothelioma treatment and diagnosis.

Labels: diagnosis, mesothelioma, staging, surgery, treatments