According to this logic, a low-dose decitabine combined with a reduced-dose CAG (cytotoxic drug at half the dose of the previous CAG) regimen (DCAG) was recently designed in our center for the treatment of elderly AML. i) G-CSF pre-stimulation therapy: application of decitabine 6 h after G-CSF is more likely to promote cell differentiation, while for hypoproliferative leukemia cells, stimulating cells from G0/G1 phase into S phase, facilitating the removal of DNMT1. ii) Decitabine selection 15 mg/m2/d×5 days: according to the degree of in vivo decitabine dose on DNA methylation removal, i.e. 15 mg/m2/d vs. facilitate the removal of DNMT1; ②Decitabine selection 15 mg/m2/d×5 days: according to the degree of DNA methylation removal by decitabine dose in vivo, i.e. 15 mg/m2/d is almost equal to or lower than 20 mg/m2/d recommended by FDA, and then refer to the 5-day regimen of 20 mg/m2 total decitabine recommended by FDA ③ Decitabine application 48 h after combined with low-dose aclarubicin and In October 2010, our center used DCAG induction therapy to treat a 78-year-old AML-M2 patient and achieved CR in one course of treatment, and then maintained consolidation therapy. We organized a national multicenter clinical trial (ChiCTR-ONC-11001700) with the participation of more than 10 centers in China. 50 elderly patients with AML and high-risk MDS received DCAG induction therapy, with a median age of 65 (60-80 years) years, 15 patients aged 370 years, 48 evaluable patients, CR 77.1%, 4 week early mortality of 5.7% and 7/13 patients with abnormal cytogenetics achieved complete cytogenetic remission. Neutrophils recovered to 0.5×109/L in a median of 12 days and platelets to 20×109/L in a median of 11 days. Conventional chemotherapy does not cure most elderly AML, and the 5-year overall survival rates for elderly AML patients with good, intermediate, and poor chromosomal stratification prognosis were 19%, 7%, and 0%, respectively, according to the results reported by different study centers. Elderly AML is not the best candidate for allo-HSCT because of poor physical fitness, multiple concomitant various organ insufficiencies, and diminished compensatory function. The advantages of transplantation are known to be low disease recurrence and long disease-free survival, but treatment-related mortality is high in elderly patients. The use of non-cleared marrow transplantation or reduced dose preconditioning (RIC) regimens in recent years has significantly reduced the risks associated with transplantation, making it possible for elderly AML patients to receive allo-HSCT. Data from the Center for International Blood and Marrow Transplantation Research (CIBMTR) show that the proportion of AML patients over 60 years of age receiving non-cleared marrow or RIC transplantation has increased over the last decade, with approximately 6% of primary care elderly AML patients receiving allo-HSCT each year. retrospective analyses show that RIC transplantation appears to be superior to chemotherapy alone, but the benefits of this transplantation are mainly limited to elderly AML patients <70 years of age. A single-center study by Lübbert et al. attempted to reduce transplant-related mortality by pre-transplant bridging effects of decitabine and to enhance graft-versus-leukemia (GVL) effects by upregulating HLA expression. The authors reported 15 elderly patients with a median age of 69 years (9 AML, 6 MDS), all treated with decitabine 15 mg/m2, q8h, for 3 days, for 6 weekly cycles. The pretreatment regimen was fludarabine, carmustine, and marfalan. There was no increase in the incidence of graft-versus-host disease (GVHD), with a median time to remission of 5 months after transplantation, a 1-year survival rate of 47%, and a 2-year survival rate of 30%. Elderly AML patients capable of transplantation were screened according to five parameters: responsiveness to induction chemotherapy, cytogenetic and molecular biological stratification, comorbidities, and HLA-compatible donors. Recently, Professor Ai Huisheng in China used conventional chemotherapy (mitoxantrone + cytarabine) combined with microtransplantation to treat 30 cases of elderly AML with a median age of 68 years (60-88 years), and the remission rate and median survival were significantly higher than those with chemotherapy alone, no GVHD occurred, and the 2-year overall survival rate reached 38.9%, and neutrophils and platelets recovered faster than in the conventional chemotherapy group. In August 2013, our center used DCAG combined with microtransplantation to treat 4 cases of AML in elderly patients aged 70 years or older, 2 of them were with high leukocyte leukemia, all 4 cases reached CR, and the median follow-up was 5 months. We look forward to seeing reports of related studies in the near future. The FDA recommended dose of decitabine is 20 mg/m2/d for 5 days, and many clinical trials have used this dose alone or in combination for the treatment of AML and MDS; however, at the 2013 American Congress of Hematology, Saunthararajah proposed an ultra-low dose of decitabine for the treatment of MDS, which has the advantage of significantly reducing the side effects of decitabine while ensuring efficacy. The article emphasizes that the dose of decitabine is sufficient to achieve DNMT1 removal, which can be achieved by increasing the frequency of decitabine application and exposing more S-stage tumor cells to decitabine. In vitro trials have also demonstrated that decitabine 3.5-7 mg/m2/d more than 3 times a week is sufficient to achieve epigenetic effects and promote hematopoietic stem cell differentiation without cytotoxic effects. mahfouz et al. reported that ultra-low doses of decitabine for MDS [0.1-0.2 mg/kg (equivalent to 3.5-7 mg/m2) subcutaneously, 1-3 times/week] had an overall response rate of 44%, and complete hematologic response and complete cytogenetic response could be obtained even with high-risk MDS. On the other hand, clinical trials found higher efficacy of azacitidine than decitabine in the treatment of MDS, with associated granulocyte deficiency-induced fever being rare. Further analysis revealed that azacitidine is a precursor to decitabine phosphate, and the FDA recommends a conventional dose of azacitidine of 50-75 mg/m2 approximately equivalent to decitabine at 7.5 mg/m2. It is believed that future clinical trials will further explore whether decitabine dosing should continue at 20 mg/m2/d x 5 days or be changed to ultra-low doses or other doses that are more appropriate for elderly AML? The heterogeneity of elderly AML heterogeneity makes it difficult to anticipate the efficacy of treatment and to recommend conventional treatment regimens. Can the characteristics of elderly AML patients at presentation guide treatment and predict survival? Comprehensive evaluation models exist for prognostic indicators and prediction of AML in the elderly, with parameters including age, physical status, comorbidities, cytogenetics, white blood cell count, and AML type, but it is unclear which model is the most accurate. The intensive study of hypomethylating agents has opened a new chapter in the treatment of elderly AML, and the start of microtransplantation has allowed more elderly AML patients of advanced age (≥70 years, or even 80+ years) to be treated and prolong their survival without compromising quality of life. In general, intense chemotherapy may be appropriate for physically grade 0-II, comorbid-free, <70-year-old AML with responders followed by non-cleared marrow or RIC transplantation; and since most elderly AML cannot extend overall survival by increasing the regimen of cytotoxic drugs, the choice of drugs (e.g., low- or ultra-low-dose hypomethylating drugs) and components (e.g., prepared perforated donor stem cells) in combination with low doses of cytotoxic drugs may be a focus for future research.