This cross-sectional study was conducted between December 2015 to September 2017 in the Department of Hematology and Oncology, Tabriz University of Medical Sciences. This study has been approved as a confirmed research proposal (94/13) and obtaining the permission of the Ethics Committee of Tabriz University of Medical Sciences (TBZMED.REC.1394.793). Ethical consent forms were obtained from a ll patients.

All patients aged 15-60 years with newly diagnosed AML and other than AML (M3), based on morphological and flow cytometric criteria, and patients with a cardiac ejection fraction of more than 50% were included in this study.

Patients during pregnancy and breastfeeding, or having malignancies and secondary or previously treated for AML, and patients with a cardiac ejection fraction of less than 50% were excluded.

After confirmation of the diagnosis of AML according to WHO diagnostic criteria (presence of more than 20% of myeloblasts in bone marrow)7, patients were treated with an induction regimen of 7 + 3. Morphological evaluation of cells, immune-histo-chemical staining, flow cytometric characteristics, and cytogenetic analysis for patients were performed.

Patients were treated with Cytarabine (Ebewe, Austria) 100 mg/m² as a 24-hour intravenous infusion for 7 days, and Daunorubicin 90 mg/m² (Pfizer, Germany) was infused intravenously for three days18. At the 30^th day after treatment started, patients were evaluated for response to treatment by bone marrow aspiration.

In the case of complete remission (19), which included neutrophil count over 1000, platelet count above 100,000, absence of premature cells in peripheral blood and less than 5% in bone marrow, and absence of Auerrod, patients were treated with Cytarabine (100 mg/m²) as infusion during 24-hour for 5 days, and 45 mg/m² of Daunorubicin as intravenous infusion for two days. This treatment was repeated with an interval of one month, and patients underwent monthly blood tests until relapse or death due to non-AML.

Prognostic outcomes were assessed as overall survival (OS) and disease - free survival (DFS). Overall survival was determined at the time of diagnosis and the date of death or the last follow-up. DFS was evaluated at the time interval between the diagnosis date and the date of the first relapse or the last follow-up.

The survival analysis was performed using the Kaplan-Meier method and the log-rank test for evaluating the differences between mentioned factors. Data analysis was performed by SPSS software version 21.

Sixteen patients were recruited in this study, including 7 (43.8%) females and 9 (56.2%) males. The patients were between 16-54 years old, and their mean age was 38 ± 12.38 years. The most common detected sub-type was AML, M2 (n=9, 56.25%). Table 1 shows the frequency of AML different subtypes (Table 1).

AML Subtype	Frequency	Percent
M0	1	6.25%
M1	3	18.75%
M2	9	56.25%
M4	3	18.75%
M5	-	-

Table 1

The median white blood cell count was 2125.0/cm^{3 (800 to 83480), with mean hemoglobin levels of 5.88 ± 2.66 g/dl, and the median platelet count was 29500.0/mm3 (5000 to 42000).}

In 13 patients (81.3%), fever was reported, and mucositis was detected in 10 patients (62.5 %). The highest and lowest neutropenic periods in patients were 8 days and 26 days, respectively. The median duration of neutropenia was 23 days. The maximum and minimum days for antibiotic treatment were 8 days and 26 days, respectively, and the median duration of antibiotic therapy was 8 days. From 16 AML patients, only one patient had evidence of cardiac function reduction. Eleven AMLs (68.8%) had complete remission, and there was no significant difference between the type of AML and complete remission response rate (P = 0.5).

The mean follow-up time was 216.44 ± 178.08 days in 16 AML patients. The overall survival was 81.3%, with the mean OS of 396.88 days (95% CI: 306.261-486.765). The highest overall survival was observed for M2 sub-type, but there was no significant difference in prognosis between different AML sub-types (P Log-rank = 0.0 67). Although male patients had lower OS than females (77.8% vs. 85.7%), this difference was not significant (P Log-rank=0.640) (Figure 1).

Figure 1

The disease-free survival (DFS) was 83.3%, with a mean of 383.57 days (95% CI: 299.88 – 467.26). None of the M2 sub-types had relapsed during the study period, and so there was a significant difference in DFS between AML sub-types (P Log-rank=0.013). From each of the male and female AML cases, one patient had relapsed (P Log-rank= 0.728) (Figure 2).

Figure 2

We followed 16 AML patients in two years to evaluate the prognostic effect of treatment with 90 mg/m²/day of Daunorubicin. The most common detected sub-type was AML, M2 (n=9, 56.25%), and there was a significant difference of DFS between different sub-types, while none of the M2 sub-types had relapsed.

Recently Lee et al. (2016) showed the effectiveness of increasing Daunorubicin doses to 90 mg/m²/day compared to 45 mg/m²/day dosage, in the form of 7+3 protocol in patients younger than 60 years.

The overall remission rate was 70.6% vs. 57.33% (P<0.001), and the overall survival rate was 23.7 months, compared to 15.7 months (P=0.005)18. In another study, the complete remission rate was 82.5% vs. 72%, in the groups receiving the same protocols. Overall survival rate (46.8% vs. 34.6%) and the disease survival rate (8.8% and 28.4%) were significantly higher in AMLs, who received 90 mg/m²/day Daunorubicin19.

In Löwenberg et al. study, complete remission (CR) was 73% in AMLs receiving 90 mg/m² of Daunorubicin, compared with 51% CR of the standard care with 45 mg/m² (P = 0.08). The overall survival (38% vs. 23% P=0.16) was not significantly different between the two groups20.

Appelbaum et al. evaluated AML patients treated with a standard dose (45 mg/m²) and suggested dose (90 mg/m²) of Daunorubicin19. Their results showed that high dose Daunorubicin significantly increased patient's survival (P=0.0003). We could not find any significant difference in OS between different AML sub-types, but there was a significant DFS between groups. Considering the controversial results of different studies, further studies with better study designs and larger sample size are required to demonstrate the effective response to high doses (90 mg/m²) of Daunorubicin.

In this study, there was not any significant relationship between AML sub-types and overall survival in patients with acute myeloid leukemia, which was due to the small size in the study. In the case of a multicentre study, improvement in the results may be achieved by increasing the sample size.

AML: Acute Myeloid Leukemia

CI: Confidence Interval

CR: Complete Remission

DFS: Diseases Free Survival

OS: Overall Survival

WHO: World Health Organization

1) R.D., E.I.J., and Z.S. made substantial contributions to the conception and design of the work; and the acquisition, analysis, interpretation of data;

2) A.N., A.E., S.H.C., B.N. made data extraction and management;

3) R.D., E.I.J., and Z.S. drafted the work or revised it critically for important intellectual content;

4) All authors approved the version to be published; and

5) All authors agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

None of the authors of this article have conflicting interests.

The authors would like to thank all the patients participating in this research and the Hematology and Oncology Research Center of Tabriz University of Medical Sciences to support this proposal (Scheme: 94/13), approved by the Ethics Committee of the Tabriz University of Medical Sciences (TBZMED. REC.1394.793). The present study is a thesis of Dr. Effat Irani Jam, MD, in the Faculty of Medicine, Tabriz University of Medical Sciences (Thesis no: 94/5-10/4).

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