Lymphomas are a group of malignancies of lymphoid tissue. They are classified as either non-Hodgkin's or Hodgkin's lymphoma. While lymphomas generally affect lymph nodes or lymphoid tissue, such as the spleen, they can also affect extranodal tissue, such as the lung, liver, or gastrointestinal tract.
Non-Hodgkin's lymphomas are the sixth most common cause of cancer-related death in the United States. Since 1950, the age-adjusted death rate has more than doubled. These cancers are characterized as B-cell (90%) or T-cell lymphomas, depending on the lymphoid cell of origin. The classification of non-Hodgkin's lymphoma has more than 40 separate diagnoses. Untreated, the most aggressive forms have an abysmal prognosis, with survival rates measured in weeks or months. However, with appropriate treatment, many of the aggressive types are curable. On the other hand, the less aggressive types may not need immediate treatment, but they are generally not considered curable.
Hodgkin-s lymphoma is characterized by the histologic presence of the Reed-Sternberg cell. There are 5 types of Hodgkin's lymphoma, differentiated by histologic appearance:
- Nodular sclerosing Hodgkin's lymphoma.
- Mixed cellularity Hodgkin's lymphoma.
- Lymphocyte depletion Hodgkin's lymphoma.
- Lymphocyte-rich classical Hodgkin's lymphoma.
- Nodular lymphocyte-predominant Hodgkin's lymphoma.
Overall, Hodgkin's lymphoma currently has a cure rate of more than 85%. The different types are generally treated similarly and have comparable outcomes.
Presenting symptoms of both categories of lymphoma include painless lymphadenopathy; constitutional symptoms (eg, fever, night sweats, weight loss, fatigue); pruritis; and symptoms of localized compression, such as coughing and chest discomfort. However, indolent lymphomas are often asymptomatic at presentation.
- Increasing age. Although the disease occurs in all age groups, incidence rises dramatically after age 50.
- Family history. Individuals with one or more affected first-degree relatives have twice the usual risk.
- Exposure history. Herbicides and other organic chemicals have been linked to an increased risk.
- Immunodeficiency disorders. These include immune deficiency states, chronic immunosuppression, and auto-immune diseases.
- Infectious agents. Viral (eg, HIV, Epstein-Barr virus, human T-cell lymphotropic virus type I, human herpes virus type 8) and bacterial (H pylori) infections have been associated with an increased risk of specific types of lymphoma.
- Age. There is a bimodal age distribution with peak incidence in young adults (ages 15-35) and in individuals older than 50.
- Male gender. The condition is more prevalent in males, especially in children and younger adults.
- Geography. Incidence increases in areas with high industrial development.
- Genetics. There is nearly a 100-fold increased risk in monozygotic twins and, at least among young patients, a 7-fold increased risk among siblings of Hodgkin's disease patients. Although associations between certain HLA haplotypes and risk of Hodgkin's disease have been identified, it remains unclear whether the increased familial risk is due to a genetic susceptibility or common environmental exposures.
- Infectious agents. Several associations have suggested a link between Epstein-Barr virus and Hodgkin's disease. Other infectious etiologies may play a role.
- Breast-feeding. In several studies, breast-feeding has been associated with reduced risk of Hodgkin's disease.
Diagnosis and Treatment
Biopsy of a lymph node or extranodal site of involvement is diagnostic. Histologic findings determine the type and classification of lymphoma.
Following diagnosis, staging is done to determine the extent of disease. Necessary laboratory testing includes a complete blood count, chemistry panel, lactate dehydrogenase, uric acid, C-reactive protein, serum protein electrophoresis, and β2 microglobulin. Computed tomography (CT) scans of the thorax, abdomen, and pelvis are used to document both lymphadenopathy and extranodal involvement.
In many cases, a bone marrow biopsy will be performed to assess marrow involvement. Positron emission tomography (PET) scans are increasingly being used for both initial staging and assessment of treatment response.
Radiation and/or chemotherapy are the mainstays of treatment.
Aggressive non-Hodgkin's lymphoma types and advanced Hodgkin's lymphoma require combination chemotherapy. In cases of bulky disease, radiation therapy to the affected area may be considered. Localized Hodgkin's lymphoma is treated with radiation therapy to the affected area.
As the cure rate of Hodgkin's disease has improved, research has focused on decreasing the toxicity and long-term consequences of treatment, especially second malignancies.
Observation alone without specific treatment is common in asymptomatic non-Hodgkin's lymphoma patients with indolent histologies.
Bone marrow transplantation is an option for some patients.
Only a limited number of research studies have addressed associations between diet and risk for lymphoma. The following factors have been under study for possible roles in reducing risk:
Reducing or avoiding intake of animal products. Compared with individuals who eat beef, pork, or lamb less than once per week, those who eat these foods daily had more than twice the risk for non-Hodgkin's lymphoma.1 Intake of foods high in saturated fat, particularly hamburger and other red meats, was also associated with roughly twice the risk for this cancer.2 Lymphoma risk associated with milk intake is 1.5 times greater for persons who drink the most milk than for those who drink the least.3 Individuals who drink > 2 glasses of milk per day have 3 times the lymphoma risk of those who drink less than 1 glass per day.4
Reducing intake of fats, particularly trans fats. The evidence linking fat intake by itself to lymphoma is not as strong as that linking saturated fat to the disease. Nevertheless, a high intake of transfatty acids is associated with 2.4 times the risk for lymphoma in persons eating the greatest amount of these fats, compared with those who eat the least.1 Individuals eating the highest amount of total fat have a 28% higher risk for lymphoma than those eating the least.5
Increasing intake of fruits and vegetables. Compared with women eating 3 daily servings of fruits and vegetables, those who ate 6 or more servings per day had a 40% lower risk for non-Hodgkin's lymphoma.6 Cruciferous vegetables may be particularly protective: women consuming them 2 or more times a week had a 30% lower risk for non-Hodgkin's lymphoma, compared with women who ate these vegetables less than twice per month.7
A high-fiber diet. Individuals consuming the largest amount of whole grains or dietary fiber from fruits and vegetables had roughly half the risk for non-Hodgkin's lymphoma, compared with those eating the least amount from these food categories.6-8
A gluten-free diet for individuals with celiac disease. Patients with celiac disease have a higher risk for several types of cancer, and their risk for non-Hodgkin's lymphoma is 9 times that of the general population. The risk for cancer overall is reduced considerably with a gluten-free diet. However, the risk for non-Hodgkin's lymphoma in these patients is still 6 times that of the general population.9 Patients with dermatitis herpetiformis, a condition often experienced by individuals with celiac disease, also more frequently develop lymphomas of both the B-cell and T-cell variety, although this risk is reduced by following a gluten-free diet.10
Maintenance of a healthy weight. Studies suggest that being significantly overweight may increase the risk for non-Hodgkin's lymphoma. The risk for lymphoma associated with obesity has ranged from 1.5 times greater in persons with a body mass index (BMI) of >30 kg/m2, to 2 times greater in those with a BMI of >35 kg/m2, compared with individuals having a BMI of <25 kg/m2.11,12
What to Tell the Family
Lymphoma is a complex group of over 40 diseases. The treatment plan and prognosis vary widely among the different types. In general, lymphomas are highly treatable, and over 50% of individuals survive non-Hodgkin's lymphoma beyond 5 years. Family members can support the patient by following a similar healthy diet.
5. Purdue MP, Bassani DG, Klar NS, Sloan M, Kreiger N, and the Canadian Cancer Registries Epidemiology Research Group. Dietary factors and risk of non-Hodgkin's lymphoma by histologic subtype: a case-control analysis. Cancer Epidemiol Biomarkers Prev.2004;13:1665-1676.
11. Pan SY, Mao Y, Ugnat AM, and the Canadian Cancer Registries Epidemiology Research Group. Physical activity, obesity, energy intake, and the risk of non-Hodgkin's lymphoma: a population-based case-control study. Am J Epidemiol. 2005;162:1162-1173.