Assessment Of The Value Of a Day 14 Bone Marrow In Newly Diagnosed AML

Mangement of AML typically calls for a bone marrow aspirate 7-10 days after completion of induction therapy with standard or high-dose cytarabine (HiDAC)-containing regimens (day 14 marrow). If this marrow contains >5-10% blasts, National Comprehensive Cancer Network guidelines recommend a second course of induction therapy. However, nearly 70% of patients who have persistent blasts in a day 14 marrow do not begin reinduction within 1 week. Additionally, at least in patients given higher doses of cytarabine as part of induction therapy, blast counts often continue to decrease between days 14 and 21, and many such patients will achieve complete remission (CR) without a second induction. These findings call into question the value of a day 14 marrow.

Our database contained 154 patients with newly diagnosed AML or MDS with 10-19% blasts seen in our hospital from 2008-2013. Patients lived at least 21 days after receiving induction therapy with regimens containing standard-dose cytarabine (114 patients, typically given “3+7” ) or high-dose cytarabine (40 patients). The treatments were not given on protocol, thus granting physicians discretion to determine when to examine the marrow. Marrow exams performed between days 10 and 17 after starting induction were considered a “day 14 marrow.” Response was assessed at least 21 days from the start of the initial induction course. Our goals were (1) to identify pretreatment factors (described below) associated with the decision to obtain a day 14 marrow and (2) to determine the influence obtaining a day 14 marrow had on the likelihood of CR on course 1, after accounting, by multivariable logistic regression, for age, cytogenetic risk (SWOG criteria), pretreatment blast % (morphologic count in marrow; peripheral blood if no marrow available), and type of AML (de novo vs. secondary).

116 of 154 patients (75%) had a day 14 marrow. Patients who had and did not have a day 14 marrow were similarly-aged (average 53 in both groups), had similar pretreatment blast percentages (52% vs 47%, respectively), and had a similar proportion with de novo AML (66% vs 68%). Patients who had a day 14 marrow more often received 3+7 (79% of standard-dose cytarabine patients had a day 14 marrow vs 65% of HiDAC, p=0.06). Only 60% of patients with favorable risk cytogenetics had a day 14 marrow vs 79% of patients with intermediate or unfavorable risk (p=0.03). Considering the 3+7 group separately, only a higher pretreatment blast count predicted the likelihood of a day 14 marrow (53% with a day 14 marrow vs 38% without, p=0.02). No factors were predictive in the HiDAC group.

As expected, favorable cytogenetics were associated with a higher CR rate while age, pretreatment blast %, and de novo vs secondary AML did not influence CR. After accounting for these covariates, there was no difference in the rate of CR between patients who did and did not have a day 14 marrow (66% vs 74%, p=0.61). The same was true when standard and high-dose cytarabine were analyzed separately (p=0.80 and 0.26, respectively). 18 patients with a day 14 marrow had resistant disease and received a second induction course; of these, two achieved CR. Likewise, two patients without a day 14 marrow were reinduced for resistant disease, and one entered CR. While the response to the second induction was not included in the analysis, results would not be expected to vary significantly given the CR rates with the second course.

These results suggest that while patients are more likely to have a day 14 marrow if they have intermediate- or poor-risk cytogenetics and receive 3+7, the decision to obtain a day 14 marrow does not lead to a higher CR rate.

No relevant conflicts of interest to declare.