)More recently, the use of positron emission tomography (PET) early after commencing chemotherapy has demonstrated to have powerful prognostic ability. This enables assessment of an individuals response to chemotherapy as the PET activity switches off rapidly in people who are responding. In this study, after two cycles of ABVD chemotherapy, 83% of people were free of disease at 3 years if they had a negative PET versus only 28% in those with positive PET scans. This prognostic method improves on FFP estimates based on the seven conventional factors. Several trials are underway to see if PET-based risk adapted response can be used to improve a persons outcomes by changing chemotherapy early in people who are not responding. The evidence is very uncertain about the effect of negative (= good prognosis) or positive (= bad prognosis) interim PET scan results for patients with a Hodgkins lymphoma on the progression-free survival. Negative interim PET scan results may result in an increase in progression-free survival compared if the adjusted result was measured. Negative interim PET scan results probably result in a large increase in the overall survival compared to those with a positive interim PET scan result,

Epidemiology
Unlike some other lymphomas, whose number of new cases per year increases with age, Hodgkin lymphoma has a bimodal curve for the number of cases; that is, it occurs most frequently in two separate age groups, the first being young adulthood (age 15–35) and the second being in those over 55 years old although these peaks may vary slightly with nationality.
Although Hodgkins is now frequently grouped with other B-cell malignancies, some T-cell markers (such as CD2 and CD4) are occasionally expressed. However, this may be an artifact of the ambiguity inherent in the diagnosis. Hodgkin cells produce interleukin-21 (IL-21), which was once thought to be exclusive to T-cells. This feature may explain the behavior of classic Hodgkin lymphoma, including clusters of other immune cells gathered around HL cells (infiltrate) in cultures. Nodular lymphocyte predominant
Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is another subtype of Hodgkin lymphoma distinct from classic Hodgkin lymphoma and is characterized by the presence of popcorn cells which express CD20. Due to these differences, among others, NLPHL is often treated differently from classic Hodgkin lymphoma, including using rituximab in combination with AVBD chemotherapy, though individual cases vary and clinical trials are ongoing. Staging
The staging is the same for both Hodgkin and non-Hodgkin lymphomas. After Hodgkin lymphoma is diagnosed, a person will be staged: that is, they will undergo a series of tests and procedures that will determine what areas of the body are affected. These procedures may include documentation of their histology, a physical examination, blood tests, chest X-ray radiographs, computed tomography (CT)/positron emission tomography (PET)/magnetic resonance imaging (MRI) scans of the chest, abdomen and pelvis, and usually a bone marrow biopsy. PET scan is now used instead of the gallium scan for staging. On the PET scan, sites involved with lymphoma light up very brightly enabling accurate and reproducible imaging.