Obesity Is a Poor Prognostic Factor In Acute Promyelocytic Leukemia (APL).

The association between increase in body mass index (BMI) and development of acute promyelocytic leukemia (APL) has been reported. Interaction of APL cells with bone marrow adipocytes in vitro induces phosphorylation of STAT3 and MAPK, resulting in an anti-apoptotic effect in APL cells. However, the influence of obesity on the prognosis of APL is not well understood.

To evaluate the effect of obesity on the prognosis of adult APL, we retrospectively analyzed 62 patients under the age of 65 with newly diagnosed APL. Patients who could not be administered intensified chemotherapy, because of either poor performance status or adverse events of chemotherapy, were excluded.

Median age of patients was 40 years (range, 14–63). Twenty-five were male and 37 were female. Median follow-up period was 646 days (range, 3–12,558). Median BMI was 22.7 (range, 16.0–33.0). Twenty-six patients diagnosed with APL between 1970 and 1992 had been treated with chemotherapy alone (chemotherapy group), and 36 patients diagnosed between 1995 and 2010 had been treated with all-trans retinoic acid (ATRA) ± chemotherapy (ATRA group). In both groups, the outcome was compared between high-BMI (BMI ≥ 24) and low-BMI (BMI < 24) patients. Eight out of 26 in the chemotherapy group and 16 out of 36 in the ATRA group were high-BMI patients.

In the chemotherapy group, complete remission (CR) was obtained in 13 out of 18 (72.2%) low-BMI patients and in only 3 out of 8 (37.5%) high-BMI patients. By day 498, all 3 CR patients with high BMI had relapsed, whereas only 6 out of 13 (46.2%) low-BMI CR patients had relapsed. The 2-year relapse-free survival (RFS) rate, event-free survival (EFS) rate, and overall survival (OS) rate in high-BMI versus low-BMI patients were 0% v 50.5%, 0% v 61.1%, and 12.5% v 42.8%, respectively. Although the relapsed patients were salvaged with ATRA, arsenic trioxide, or allogeneic bone marrow transplantation, OS was significantly worse in high-BMI patients. On the contrary, in the ATRA group, prognosis between high-BMI and low-BMI patients was not statistically different. Rates of CR, relapse, 2-year RFS, EFS, and OS in high-BMI versus low-BMI patients were 87.5% v 94.7%, 35.7% v 38.9%, 73.3% v 46.2%, 55.0% v 52.5%, and 87.5% v 81.1%, respectively.

The initial white blood cell (WBC) and platelet counts have been previously reported to be prognostic factors in APL; however, they were not associated with BMI in our study. A WBC count of >10 × 10⁹/L and a platelet count of ≤40 × 10⁹/L were observed in 4 (10.5%) and 28 (73.8%) out of 38 low-BMI, and 4 (16.5%) and 19 (79.2%) out of 24 high-BMI patients, respectively.

Our results demonstrate that obesity at diagnosis is a poor prognostic factor in APL, especially in patients not administered ATRA. ATRA overcomes the anti-apoptotic effect of adipocytes for APL cells.

No relevant conflicts of interest to declare.