Concurrent radiotherapy does not affect adjuvant CMF delivery but is associated with increased toxicity in women with early breast cancer

We evaluated whether concurrent radiotherapy (RT) affected delivery and toxicity of adjuvant intravenous CMF (cyclophosphamide, methotrexate and 5-fluorouracil) in women with operable breast cancer. The medical charts of 321 consecutive breast cancer patients who received CMF either alone for 6 cycles, or for 4 cycles following of an anthracycline (A-CMF) were reviewed. One hundred forty-four women underwent radiotherapy concurrently with CMF. Optimal CMF delivery (success as opposite to failure) was defined as the combined achievement of an average relative dose intensity (aRDI) > or = 85% and an average percent of the total dose (aPTD) > or = 90% for the three drugs in the CMF regimen. Multivariate logistic regression analysis showed that concurrent-RT did not affect CMF delivery (OR for success 1.391 p=0.230). The sequential A-CMF regimen (OR for success 0.208, 95% C.I. 0.120-0.360, p<0.001) and age > or = 56 (OR for success 0.351, 95% C.I. 0.200-0.161, p<0.001) were independently associated with suboptimal CMF delivery. Moreover, concurrent RT was independently associated with increased leukopenia, thrombocytopenia, upper abdominal pain, mucositis and fatigue. Our retrospective analysis suggests that concurrent-RT has no impact on optimal CMF delivery, but it increases the burden of CMF-related toxicity.