Today, we can cure a significant portion of people with aggressive non-Hodgkin's lymphomas. The cure rate at 5 years for all patients with advanced diffuse large-cell lymphoma is approximately 35%. Patients with localized disease are cured the majority of the time. However, it is important to be able to predict an individual patient's chance for benefit.
In her talk at the Pan Pacific Lymphoma Conference, Dr. Margaret Shipp of Dana-Farber Cancer Center described an international study involving several thousand patients with aggressive non-Hodgkin's lymphoma that established the International Prognostic Index. The patients were treated in the 1980s with active combination chemotherapy regimens.
This study identified five factors that strongly predicted outcome: Ann Arbor stage, age, serum LDH level, performance status, and number of extranodal sites of involvement. When only young patients were considered, Ann Arbor stage, serum LDH level, and performance status were the major prognostic factors.
By adding together the adverse factors present in an individual patient, it is possible to predict the patient's chances of survival when treated with standard anthracycline-containing combination chemotherapy regimens. Patients with a very good outlook should probably receive current standard therapies, and future studies in these patients might be aimed at efforts to reduce toxicity. However, we need new treatments for those who have a very poor outlook.
It is important to understand why these clinical factors predict outcome. It must be that they are indirect representations of adverse characteristics of the tumor. For example, such factors as tumor proliferative rate, mass size, and serum LDH level might reflect abnormalities in tumor growth and invasive potential. Such abnormalities as B symptoms and performance status might be reflections of the patient's ability to respond to the tumor. Finally, factors such as the patient's age might be a reflection of the patient's ability to tolerate therapy.
The International Prognostic Index has recently been demonstrated to work fairly well for patients with low-grade non-Hodgkin's lymphomas, and it is likely that it might be used in planning clinical trials in these tumors as well as in the aggressive non-Hodgkin's lymphomas.