Early-Stage Hodgkin Lymphoma

INITIAL EVALUATION AND STAGING

The initial workup includes a complete blood count (CBC), erythrocyte sedimentation rate (ESR), lactate dehydrogenase (LDH), and chemistry studies to evaluate renal function and liver function. Fine-needle aspiration will usually fail to identify the infrequent HRS cells, and instead only reveal the reactive background of inflammatory cells. Generous (large gauge) core needle biopsies may provide diagnosis effectively in some cases, but in general, an excisional lymph node biopsy is preferred to ensure an accurate diagnosis and avoid the need for repeated biopsy procedures. In cases where an excisional biopsy would be difficult or risky, a core needle biopsy procedure is a reasonable first step, with the understanding that a subsequent surgical procedure may still be necessary.

Baseline imaging includes CT scans of the neck, chest, abdomen, and pelvis. Use of positron emission tomography (PET) scanning is now standard in the initial evaluation and assessment of treatment response in Hodgkin lymphoma.³⁶ Due to the increased sensitivity of PET or PET/CT scan, additional lesions may be identified that were not seen on conventional CT scans. This will alter the staging, and potentially the treatment plan, in up to 25% to 30% of patients.^37,38 PET/CT scan performed during initial evaluation also facilitates optimal interpretation of post-therapy PET/CT scans and is therefore strongly encouraged as a part of the initial staging evaluation.³⁹

Recent studies have shown that bone marrow biopsy is not routinely needed in the initial staging of cHL. A study of 454 patients concluded that bone marrow biopsy would not have altered the stage in any stage I or II patients. It was further concluded that overall treatment strategy would not have been altered for any of the patients.⁴⁰ Based on this study and others, it is now clear that FDG-PET has a high sensitivity, and when PET scan is negative (in the bone marrow and skeleton), a bone marrow biopsy provides little additional value. For patients with significant cytopenias, a bone marrow biopsy is reasonable. Such patients may benefit from a bilateral biopsy, which increases the probability of demonstrating bone marrow involvement by 16% to 33%.^41,42 Techniques such as staging laparotomy and lymphangiography are now considered obsolete.

Hodgkin lymphoma is staged according to the Ann Arbor staging system (Table 1). The original Ann Arbor staging was published in 1971,⁴³ and in 1989 the “Cotswold modifications” extended the definitions of stage IV disease and the suffix “X” was added to denote bulky disease.⁴⁴ Both systems were developed for the staging of Hodgkin lymphoma, but are now used for staging non-Hodgkin lymphoma as well.

PROGNOSTIC FACTORS

For the purposes of prognosis and selection of treatment, Hodgkin lymphoma is commonly classified into early-stage favorable, early-stage unfavorable, and advanced stage. Early-stage Hodgkin lymphoma refers to patients with Ann Arbor stage I or stage II disease. With early-stage Hodgkin lymphoma, the prognosis varies significantly based on factors such as the presence of B symptoms, elevated erythrocyte sedimentation rate ([ESR] > 50 mm/hr), number of nodal sites involved, older age, and a large mediastinal mass. For this reason, most clinical trials to evaluate treatment strategies for early-stage Hodgkin lymphoma are based on various combinations of these risk factors. The definition of early-stage unfavorable Hodgkin lymphoma varies across different clinical trial study groups, and it is important to understand the definition in interpreting the results of these trials (Table 2).^45,46

In the German Hodgkin Study Group (GHSG) trials, early-stage Hodgkin lymphoma is stratified into a high risk (“unfavorable”) group defined by any of the following: a large mediastinal mass (one third of maximum thoracic diameter), extra-nodal disease, 3 or more nodal areas, and an ESR of > 50 mm/hr in asymptomatic patients or > 30 mm/hr in patients with B symptoms. Low-risk (“favorable”) patients lack all of these factors.⁴⁷ The European Organization for Research and Treatment of Cancer (EORTC) defines the unfavorable prognostic group as older than 50 years of age, large mediastinal adenopathy (maximum width on a chest radiograph of at least one third of the internal transverse diameter of the thorax at the level of T5 through T6 or any mass of ≥ 10 cm in the largest dimension), an ESR of 50 mm/hr and no B symptoms, or with an ESR of 30 mm/hr in those who have B symptoms, and/or 4 or more regions of involvement.⁴⁸ The National Cancer Institute of Canada (NCIC) Clinical Trials Group and the Eastern Cooperative Oncology Group (ECOG) define high-risk groups as presence of B symptoms, bulky disease with a mediastinal mass width of at least one third of the maximum chest wall diameter, or any mass greater than 10 cm, and patients with intra-abdominal disease.^49,50

Gene-expression profiling in Hodgkin lymphoma has identified a gene signature of tumor-associated macrophages that was able to identify patients with a higher risk for primary treatment failure. In an independent cohort of patients, an increased number of CD68-positive macrophages was correlated with inferior outcomes.^51,52 Studies such as these underscore the importance of the tumor “microenvironment” (ie, the nonmalignant cells within a tumor) in determining the overall clinical behavior of a malignancy. While quantification of CD68-positive macrophages has potential to be applied to routine clinical practice, prospective data using CD68 as a tool for risk-adapted therapy is lacking.