Prof. Daniel Seifu

Chemotherapy-induced hematologic toxicity is the primary reasons of dose reductions and/or delays, low relative dose intensity (RDI), and predicts anticancer response. We investigated the incidence and predictors of chemotherapy-induced hematologic toxicities and reduced RDI in Ethiopian breast cancer patients, and implication of pharmacogenetics variations. Breast cancer patients (n = 249) were enrolled prospectively to receive cyclophosphamide based chemotherapy. Hematological toxicity (neutropenia, anemia, and thrombocytopenia) were monitored throughout chemotherapy cycle. The primary and secondary outcomes were incidence of grade 3 or 4 toxicity and reduced RDI, respectively. CYP2B6∗6, CYP3A5∗3, CYP2C9 (∗2,∗3), CYP2C19 (∗2,∗3), CYP2J2∗7, POR∗28, and ABCB1 (rs3842) genotyping were done. Cox proportional hazard and logistic regression were used to estimate risk predictors of toxicity and reduced RDI, respectively. Majority (73.5%) of the patients were < 45 years of age. The incidence of grade 3 or 4 hematological toxicity was 51.0% (95% CI = 44.54-57.46%). Multivariate Cox proportional hazard regression indicated CYP2J2∗7 genotype [Hazard ratio (HR) = 1.82; 95% CI = 1.14-2.90], pretreatment grade 1 leukopenia (HR = 2.75; 95% CI = 1.47-5.15) or grade 1 or 2 neutropenia (HR = 2.75; 95% CI = 1.73-4.35) as significant predictors of hematologic toxicities. The odds of having hematologic toxicities was lower in CYP2C9∗2 or ∗3 carriers (p = 0.024). The prevalence of reduced RDI was 56.6% (95% CI = 50.3-62.9%). Higher risk of reduced RDI was associated with CYP2J2∗7 allele [Adjusted odds ratio (AOR) = 2.79; 95% CI = 1.21-6.46], BMI ≤ 18.4 kg/m2 (AOR = 5.98; 95% CI = 1.36-26.23), baseline grade 1 leukopenia (AOR = 6.09; 95% CI = 1.24-29.98), and baseline neutropenia (AOR = 3.37; 95% CI = 1.41-8.05). The odds of receiving reduced RDI was lower in patients with CYP2B6 ∗6/∗6 genotype (AOR = 0.19; 95% CI = 0.06-0.77). We report high incidence of chemotherapy-induced hematological toxicities causing larger proportion of patients to receive reduced RDI in Ethiopian breast cancer patients. Patients carrying CYP2J2∗7 allele and low baseline blood counts are at a higher risk for chemotherapy-induced hematologic toxicities and receiving reduced RDI, and may require prior support and close follow up during chemotherapy.

Emerging evidence associates vitamin D deficiency and vitamin D receptor (VDR) genetic variations with risk for breast cancer. This study investigated the prevalence of vitamin D deficiency and its association with tumor characteristics and the implications of VDR genetic variations for risk of breast cancer in Ethiopia. This unmatched case–control study involved 392 female breast cancer patients and 193 controls. The plasma 25-hydroxyvitamin D (25(OH)D3) level was quantified in chemotherapy-naïve (N = 112) and tamoxifen-treated patients (N = 89). Genotyping for the VDR common variant alleles rs7975232 (ApaI), rs2228570 (FokI), and rs731236 (TaqI) was done. Eighty-six percent of the patients were vitamin D deficient (<50 nmol/L). Chemotherapy-naïve breast cancer patients had a higher prevalence of vitamin D deficiency (91.9% vs. 78.3%) compared to the tamoxifen-treated group (p < 0.001). The prevalence of severe vitamin D deficiency (<25 nmol/L) was significantly higher in chemotherapy-naïve (41.1%) than tamoxifen-treated (11.2%) patients. Vitamin D deficiency was not significantly associated with tumor characteristics or VDR genotype. The rs2228570 GG genotype was associated with increased risk of breast cancer (OR = 1.44, 95% confidence interval = 1.01−2.06). Our result indicates that rs2228570 might be a moderate risk factor for breast cancer development in the Ethiopian population. The high prevalence of severe vitamin D deficiency in treatment-naïve breast cancer patients indicates the need for nutritional supplementation of vitamin D at the time of chemotherapy initiation.