Toxicity of docetaxel plus cyclophosphamide as adjuvant therapy for breast cancer in Chinese patients – the Hong Kong experience

Aims:   The docetaxel and cyclophosphamide (TC) regimen is increasingly popular as adjuvant chemotherapy for operable breast cancers. We conducted a retrospective study in Hong Kong to evaluate the toxicity of this regimen in Chinese patients.
Methods:   Between January 2007 and May 2008 76 female Chinese patients with resected stage I–III operated invasive breast cancer were treated with 4 cycles of TC (75 and 600 mg/m², respectively, administered i.v. every 3 weeks for four cycles) in two public regional cancer centers of Hong Kong. A total of 24 (32%) patients also received primary prophylactic ciprofloxacin (500 mg twice daily, day 5–14). Chemotherapy-related toxicities were graded by the CTCAE version 3.0.
Results:   The median age was 50 (range 26–67). A total of 68 (89%) patients successfully completed four cycles of chemotherapy. 72 (95%) and 16 (21%) patients developed grade 3–4 neutropenia and febrile neutropenia (FN) infection, respectively, in one or more cycles. However, no grade 3–4 anemia or thrombocytopenia events were observed. Other grade 3–4 non-hematological toxicities were also uncommon, apart from allergic reactions in two (3%) patients. No viral reactivation was observed among the 8 hepatitis B carriers. Patients with prophylactic ciprofloxacin had less grade 3–4 FN infection (13% vs 25%, P  = 0.214) and a higher chance of receiving the full scheduled dose (88% vs 62%, P  = 0.045) than patients without.
Conclusion:   The myelotoxicity of TC was substantially higher in Chinese patients compared with non-Chinese patients in developed countries. Routine prophylactic measures are recommended to maintain the dose levels and reduce the risk of FN.     

An Unusual Electrocardiographic Pattern of Left Ventricular Endocardial Pacing

Pacemaker stimulation of the left ventricle is expected to yield a pattern of complete right bundle branch block, however, unusual patterns have been reported. The present report is a case of an unusual electrocardiographic pattern from left ventricular endocardial pacing in a patient with an atrial septal defect and acute myocarditis complicated by complete degree atrioventricular block.     

POSITIVE CHRONOTROPIC RESPONSES PRODUCED BY α-ADRENORECEPTORS IN THE PITHED RAT

• 1 Phenylephrine (1–100 γg/kg, intravenously) produced dose-dependent increases in heart rate and blood pressure in the pithed rat.
• 2 The positive chronotropic response to phenylephrine (10 μg/kg) was reduced in a dose-dependent manner by propranolol (0.01–0.3 mg/kg), but higher doses of propranolol (up to 3 mg/kg) did not reduce the response by more than about 50%. The residual response was virtually abolished by phentolamine (0.3 mg/kg) or prazosin (3 μg/kg). Labetalol (3 mg/kg) which has both α- and β-blocking activity, also abolished the positive chronotropic response.
• 3 The pressor response to phenylephrine (1–30 μg/kg) was enhanced by propranolol (1 mg/kg) and abolished by phentolamine (1 mg/kg) and prazosin (30 μg/kg). Labetalol (3 mg/kg) reduced the response to phenylephrine by 73%.
• 4 Propranolol (0.3 mg/kg) completely blocked the chronotropic and vasodepressor effects of isoprenaline (0.1 μg/kg).
• 5 It is concluded that phenylephrine acts on both α₁- and β₁-adrenoreceptors to produce an increase in heart rate, on α₁-adrenoreceptors to produce vasoconstriction and on β₂-adrenoreceptors to produce vasodilation. This latter effect is usually masked by the predominant vasoconstrictor action.