Use of oral mucosal neutrophil counts to detect the onset and resolution of profound neutropenia following high‐dose myelosuppressive chemotherapy

Severe neutropenia following cytotoxic, anti‐cancer chemotherapy is well‐known to be associated with an increased risk of infections that may be life‐threatening, particularly if not treated immediately. Consequently, serial measurements of neutrophil counts in peripheral blood are done routinely following the administration of high‐dose myelosuppressive chemotherapy in order to monitor the onset, severity, and duration of iatrogenic neutropenia. We have studied a non‐invasive method of quantifying neutrophils recoverable from the oral mucosa, a normal tissue site of neutrophil turnover, as an alternative approach for monitoring severe, chemotherapy‐induced neutropenia. This method is based on the quantification of fluorochrome‐stained neutrophils present in timed mouthwash specimens. Blood neutrophil (ANC) and mucosal neutrophil counts (MNC) were measured repeatedly in 23 patients who had been treated with dose‐intensive chemotherapy for a variety of indications. All 23 patients developed profound neutropenia (ANC < 100/mm3), and 19 developed neutropenic fever (>101°F) during the 2 weeks following treatment. Nadirs of neutropenia defined by MNC were significantly less prolonged than those defined by the ANC. Furthermore, the onset and resolution of neutropenic fever coincided more precisely with nadirs of neutropenia defined by the MNC than with those defined by the ANC. Our findings indicate that oral mucosal neutrophil counts predict the timing of clinical events associated with neutropenia (e.g., the onset and resolution of fever) with significantly greater accuracy than blood neutrophil counts. Am. J. Hematol. 72:13–19, 2003. © 2002 Wiley‐Liss, Inc.