Ability of routine blood tests (RBTs) in asymptomatic patients (pts) with indolent non-Hodgkin lymphoma (iNHL) to detect relapse or clinically significant disease progression.

Abstract

e19027 Background: Pts with iNHL undergo active surveillance to detect disease relapse or progression. International guidelines recommend regular RBTs for surveillance but evidence for this practice is lacking. Methods: We conducted a retrospective analysis of pts aged ≥16 yrs from 2008-17 undergoing routine surveillance at 2 Australian centres for grade 1-3a follicular lymphoma (FL) or marginal zone lymphoma (MZL), to assess the utility of full blood count, lactate dehydrogenase & beta-2-microglobulin to detect progression events; (i.e relapse or progression) or to change management. Abnormal results were defined as acute deviations from local laboratory normal ranges not explained by a concurrent medical condition. Eligible pts were either treatment-naive or had achieved a response to lymphoma-directed therapy, had ≥6 mths follow up and an absence of progression events within 3 mths of prior therapy. Demographic data were collected as well as treatment, follow up appointment (appt) details including presence of signs/symptoms, RBT results, survival status & further therapy. The study was ethically approved. Results: 180 eligible pts (FL:142, MZL:38) underwent 1757 follow up appts (median follow up 38 months). RBTs were done at 83% of appts. 74 progression events occurred in a total of 62 pts; 48/74 (65%) had immediate therapy. 2/74 (3%) were detected by RBTs alone, (both treatment naïve pts); 88% by signs/symptoms & 9% by routine imaging. 20/243 (8%) of abnormal RBTs in asymptomatic pts led to a change in subsequent management (10 had imaging; 8 earlier appts; 2 repeat RBTs alone). The sensitivity & positive predictive value of abnormal RBTs to detect progression events were 39% & 9% respectively. In asymptomatic patients, the number of RBTs required to change management and to detect a progression event were 64 and 644 respectively. Conclusions: RBTs rarely detect clinically significant disease progression or relapse and seldom solely lead to a change in management in asymptomatic pts with iNHL. Clinical signs/symptoms are far more likely to detect progression or relapse. Guidelines should reflect the benefit & risk of RBTs in the clinical setting.