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An Overview of Non-Hodgkin's Lymphoma
The term Non-Hodgkin's Lymphoma (NHL) represents a spectrum of cancers arising from the immune system cells known as lymphocytes. Though any type of lymphocyte can become cancerous, the majority of NHL, especially in adults, come from the B-lymphocyte. According to the American Cancer Society (ACS), approximately 66,000 new cases of NHL will be diagnosed this year with approximately 19,000 deaths. This makes NHL the sixth and seventh most common malignancy in women and men, respectively, and the sixth and ninth most lethal cancer in women and men, respectively. The overall incidence of NHL has been increasing over the last several decades with the more aggressive sub-types showing the greatest increase in frequency. Fortunately, the overall mortality rate has been decreasing over the same time period; down 17 percent in men and down 23 percent in women (1990-2007).
Though NHL can occur at any age, the peak incidence is in the sixth to ninth decades of life. According to the American College of Surgeons - National Cancer Data Base (ACoS-NCDB), nationally 79 percent of cases occur between the ages of 50 and 90. The Community Hospitals data, as submitted to the ACoS-NCDB, indicates that 87 percent of our cases are in this age range. This difference is mainly accounted for by our generally older patient demographic and the smaller percentage of younger patients (particularly pediatric patients) in our cancer registry population. Overall, there are slightly more men than women diagnosed with NHL (54 percent and 46 percent nationally); our data show a very similar pattern (56 percent men and 44 percent women).
As mentioned earlier, NHL is a spectrum of malignancies with multiple distinct subtypes, each with its own unique biology and clinical course. The two most common sub-types are the diffuse large B cell lymphomas (DLBCL) and the follicular lymphomas. Together they represent approximately 60 percent of the NHL diagnoses. Typically, DLBCL is more common in younger individuals while follicular lymphomas are more common in older individuals. The ACoS-NCDB data on histology at diagnosis is shown in figure 1. Our higher proportion of follicular lymphomas again results from our overall older patient population.
The staging of NHL is accomplished using two distinct systems; an anatomic system based on disease location and the number of sites and the other based on prognostic factors and risk factors. The anatomic system, originally designed for Hodgkin's lymphoma, is the one used for data collection but has less prognostic value than the risk/prognostic factor based system. For NHL overall, stage at diagnosis is heavily dependent on the type of lymphoma; for example, over 50 percent of follicular lymphomas are diagnosed in Stage IV (widespread) while over 50 percent of DLBCL are diagnosed in Stage I or II (localized). Similarly, overall prognosis depends not only on stage and risk factors, but also on lymphoma type. Certain lymphomas, such as low grade follicular lymphomas, tend to have a slow pattern of growth and a long natural history even without treatment.
Though it remains important to determine the stage of a lymphoma at diagnosis, the most common types of NHL are usually considered disseminated from the outset. When a truly localized (Stage I) follicular lymphoma is identified, it can often be cured with localized radiation therapy alone. For the significant majority of lymphomas, however, treatment needs to be systemic. In fact, the original use of chemotherapy was in a patient with NHL (the treatment took place in 1943 with the drug nitrogen mustard). The drug regimens have evolved significantly since then including the recent introduction of a monoclonal antibody directed against a key B-cell surface antigen, CD-20. Though systemic therapy is key to successful lymphoma treatment, localized therapy with radiation is often used in addition to the chemotherapy. In this situation, the main use of radiation is to treat areas of lymphoma that are still present after a full course of chemotherapy.
According to the ACoS-NCDB, 69 percent of patients nationally are treated at diagnosis with some form of systemic therapy (chemotherapy and/or the anti-CD20 antibody Rituxan). At Community Hospital, that number is 66 percent and in the rest of Indiana it is 73 percent. Nineteen percent of our patients also receive adjuvant local therapy, compared to 11percent nationally. As described earlier, some types of NHL are relatively slow growing (such as the lower grade follicular lymphomas) and may not require (or benefit from) treatment at diagnosis. As our percentage of follicular lymphomas is higher, 28 percent of our patients do not receive treatment at diagnosis; this compares to 19 percent nationally and in the rest of Indiana. Despite the wide range of treatment options employed for NHL, the disease outcomes are fairly uniform. The ACoS-NCDB 5 year survival for NHL is 58 percent nationally and 54 percent at Community Hospital. By stage the 5 year survival is 72 percent for stage I (nationally and at Community Hospital) and 41 percent (Community Hospital) to 48 percent (nationally) for Stage IV disease.
The wide clinical spectrum of NHL limits general conclusions but it can be safely said that NHL is an illness that is increasing in frequency but decreasing in lethality. This is due to improvements in therapy and in the general supportive care of the oncology patient. The results at Community Hospital, in terms of diagnosis, staging, management and outcomes, compares favorably with other ACoS-accredited institutions throughout Indiana and the US. This achievement is the work of many dedicated professionals and exemplifies the quality of cancer care at Community Hospital.