Pleural mesothelioma patients may be less likely to get a true picture of their prognosis when their cancer is “staged” using the standard TNM method.
Harvard researchers came to that conclusion after comparing the actual clinical status of 472 malignant pleural mesothelioma patients (their cTNM stage) with their TNM stage as determined by pathological analysis (pTNM).
They found a significant discrepancy between clinical and pathological mesothelioma stage – and, as a result, in mesothelioma prognosis – in 6 out of 10 patients.
TNM Staging for Malignant Mesothelioma
The TNM staging criteria is a method for determining how extensive a patient’s cancer is by evaluating three parameters: tumor size (T), involvement of the lymph nodes (N), and the extent of metastasis (M).
But the Harvard doctors, who work with cancer patients at Brigham and Women’s Hospital and Massachusetts General Hospital in Boston, say the method often does not paint a true picture of the prognosis for people with pleural mesothelioma.
In their comparison of cTNM and pTNM staging among mesothelioma patients, they found that the two assessment methods agreed with each other in only 36 percent of patients.
More than 200 patients were “understaged”, meaning that their pleural mesothelioma was actually more advanced than their TNM staging would suggest. At the same time, nearly 20 percent of mesothelioma patients looked, from their TNM staging, like their cancer was more extensive than it actually was.
The discrepancies are concerning because staging is directly related to mesothelioma prognosis and prognosis is used by both patients and physicians to plan mesothelioma treatment.
Pleural Mesothelioma May Need Alternative Staging
Pleural mesothelioma has a number of unique characteristics that can make it difficult to stage correctly, including the size, shape and location of tumors on the pleural membrane surrounding the lungs.
The Harvard team believes that patients with asbestos cancer may be better served, especially from a prognostic standpoint, by an alternative cancer staging system.
They found that mesothelioma staging based on 3D CT imaging (volumetric CT or VolCT) and maximal fissural thickness (Fmax) “performed statistically significantly better as a prognostic classifier when compared in the test set with cTNM.”
In other words quantitative staging with tools like CT and Fmax may help mesothelioma patients and their doctors make better decisions about their treatments and predict their likely outcomes.
The research summary, recently published in the Journal of the National Cancer Institute, concludes, “Improved prognostic performance may be achievable by quantitative clinical staging combining VolCT and Fmax, providing a cost-effective and clinically relevant surrogate for clinical TNM stage.”
Gill, RR, et al, “Quantitative Clinical Staging for Patients with Malignant Pleural Mesothelioma”, March 1, 2918, Journal of the National Cancer Institute, pp. 258-264