Background Colorectal cancer (CRC) is the third most common cancer in Korea. The FOLFOX regimen is widely used chemotherapy in CRC, and the modified (mFOLFOX6) regimen is frequently used in the National Cancer Center in view of adverse events, patient convenience and the time for nursing. The mFOLFOX6 regimen consisted of oxaliplatin 85 mg/m2 and folinic acid 200 mg/m2 intravenous on day 1, followed by 5-FU 400 mg/m2 INTRAVENOUS and then 5-FU 2,400 mg/m2 INTRAVENOUS over 46 h, administered every 2 weeks. Although a modified regimen is used, adverse events have occurred frequently and dose modifications may be needed.
Purpose The objective of this study was to analyse the cause and pattern of dose modifications of mFOLFOX6 regimen, to determine the factors that affect dose modification in CRC patients.
Materials and methods A retrospective study was conducted on 70 patients who were diagnosed with CRC and received mFOLFOX6 between January 2009 and March 2010. Dose modification was needed in 68 patients (97.2%) and the average incidence (including delay of administration and dose reduction) was 2.90±1.58. The most frequently used way of modifying the dose was to delay the chemotherapy schedule for a week, and the primary cause of dose modification was neutropenia.
Factors that affect dose requirements include gender, age, body surface area (BSA), blood level, underlying disease, stage, metastasis, performance status (PS), previous disease and the history of drinking and smoking.
Results Dose modification and reduction occurred more frequently in patients in their 70's than in their 50's or 60's (P=0.015, 0.027, respectively). From blood level tests, patients with high alkaline phosphatase levels had more dose modification and delay of chemotherapy (P=0.035, 0.033, respectively). The dose was also modified and reduced more frequently in patients who had a case history of hypertension (P=0.046, 0.027, respectively). In the relation to the stage, patients in advanced stages had more dose modification and delayed administration than those in the first stage of CRC. The dose was modified and administration was delayed more frequently in metastatic cancer patients than non-metastatic cancer patients (P=0.021, 0.015, respectively). The incidence of dose modification and reduction increased with poorer PS (P=0.019, 0.025, respectively). In patients who had previously undergone radiotherapy, the dose was modified and reduced more frequently (P=0.259, 0.005 respectively). In those with a history of drinking, the dose was reduced more frequently (P=0.004). The dose was modified and administration was delayed more frequently in patients who had a history of smoking (P=0.001, 0.002, 0.002, respectively).
Conclusions From this study, the cause of dose modification depended on individual differences and could be predicted in advance. Further study is needed to confirm predictive factors that could affect dose modification and to apply them effectively to individual treatment.
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