Is disease bulk by coronal and transverse computed tomography a useful prognostic indicator?

Anita Kumar, from the Memorial Sloan-Kettering Cancer Center, New York, and colleagues recently published a retrospective analysis of the prognostic value of disease bulk as measured by coronal and transverse Computer Tomography (CT). The authors aimed to assess defining bulk by using the longest diameter of the largest nodal mass in either the transverse or coronal CT planes pre-treatment. Bulkiness was defined as 7cm or larger in either plane. They analyzed data from 185 early-stage pediatric and adult HL patients with grade I–II cHL who were treated with doxorubicin-containing chemotherapy +/- radiotherapy.

Highlights:

• Optimal transverse maximal diameter cut-off point = 7 cm
• Optimal coronal maximal diameter cut-off point = 10.5 cm
• Best predictor for progression was calculated to be 7 cm in either plane (bulky)
• 185 pts: 54% bulky, 46% non-bulky
• 4-year: Overall OS = 96.5%, Overall RFS = 86.8%
• 4-year bulky RFS = 80.5% vs. non-bulky RFS = 94.4%, HR = 4.21 (P=0.004)
• This prognostically relevant definition of disease bulk was validated in an independent validation cohort analysis of 38 pts

The authors stated that, in this method of defining disease bulk by CT scan, >7 cm is a useful prognostic indicator in patients who underwent chemotherapy only treatment, and that it is not prognostic for those patients who underwent chemoradiotherapy (+ CMT). The authors concluded by stating that their method of defining cHL disease bulk might be most useful in selecting patients who are the most suitable for chemotherapy by itself, and they recommend routine review of both transverse and coronal CT images in patients with early stage cHL.

Abstract: Disease bulk is an important prognostic factor in early stage Hodgkin lymphoma, but its definition is unclear in the computed tomography era. This retrospective analysis investigated the prognostic significance of bulky disease measured in transverse and coronal planes on computed tomography imaging. Early stage Hodgkin lymphoma patients (n=185) treated with chemotherapy with or without radiotherapy from 2000–2010 were included. The longest diameter of the largest lymph node mass was measured in transverse and coronal axes on pre-treatment imaging. The optimal cut off for disease bulk was maximal diameter greater than 7 cm measured in either the transverse or coronal plane. Thirty patients with maximal transverse diameter of 7 cm or under were found to have bulk in coronal axis. The 4-year overall survival was 96.5% (CI: 93.3%, 100%) and 4-year relapse-free survival was 86.8% (CI: 81.9%, 92.1%) for all patients. Relapse-free survival at four years for bulky patients was 80.5% (CI: 73%, 88.9%) compared to 94.4% (CI: 89.1%, 100%) for non-bulky; Cox HR 4.21 (CI: 1.43, 12.38) (P=0.004). In bulky patients, relapse-free survival was not impacted in patients treated with chemoradiotherapy; however, it was significantly lower in patients treated with chemotherapy alone. In an independent validation cohort of 38 patients treated with chemotherapy alone, patients with bulky disease had an inferior relapse-free survival [at 4 years, 71.1% (CI: 52.1%, 97%) vs. 94.1% (CI: 83.6%, 100%), Cox HR 5.27 (CI: 0.62, 45.16); P=0.09]. Presence of bulky disease on multidimensional computed tomography imaging is a significant prognostic factor in early stage Hodgkin lymphoma. Coronal reformations may be included for routine Hodgkin lymphoma staging evaluation. In future, our definition of disease bulk may be useful in identifying patients who are most appropriate for chemotherapy alone.