Immunochemotherapeutic increase of peripheral absolute monocyte count predicts interstitial pneumonia in lymphoma patients.

Interstitial pneumonia (IP) is one of the potentially fatal adverse events for lymphoma patients undergoing immunochemotherapy. However, the risk factors and predictive markers remain unclear for this complication. This retrospective study aims to explore whether the change of absolute monocyte count (AMC) during immunochemotherapy is correlated with IP occurrence and progression. A total of 500 lymphoma patients receiving immunochemotherapy from 2014 to 2016 were enrolled in this investigation. Interstitial pneumonia was generally diagnosed as diffused pulmonary interstitial infiltrates on computed tomography images in conjunction with respiratory symptoms or pulmonary function test, which is also adopted as a diagnosing tool of IP in this study. Among the total 500 participating patients, 40 patients were diagnosed as IP, which account for 8% of the total subjects. The median number of chemotherapy cycles for those patients prior to IP occurrence is 4. This research suggests that the increase of peripheral AMC over 0.565 × 109 /L after 2 cycles of immunochemotherapy is a great potential to develop IP. Using the method of multivariate analysis, lymphoma lung involvement and high AMC after 2 cycles of immunochemotherapy were identified as independent risk factors for IP. Most IP patients with sustained AMC elevation (>0.575 × 109 /L at IP onset) accompanied severe pulmonary symptoms, while those with AMC fall-back might tolerate subsequent immunochemotherapy. Thus, this study concludes that early increase of AMC during immunochemotherapy in lymphoma patients with lung involvement suggested a great potential to develop IP. Dynamic changes in AMC may serve as a predictive marker for IP severity and a guide for treatment adjustment for both tumor and pulmonary injuries.