Background
For many chemotherapy regimens dosed on body surface area (BSA), patients are dose-reduced, delayed, or discontinue treatment, reducing survival. Consideration of body composition may be useful in individualizing chemotherapy dosing, but few studies examine the association of body composition with chemotherapy tolerance in colon cancer.
Methods
We identified non-metastatic colon cancer patients diagnosed from 2006–2011 at Kaiser Permanente who received FOLFOX as initial adjuvant chemotherapy (n=533). We quantified patients’ muscle mass using clinically-acquired computed tomography (CT) scans and quantified chemotherapy doses, treatment dates, and related toxicities using the electronic medical record. In logistic regression models adjusting for age, sex, and stage, we examined associations of muscle tertiles with early discontinuation (<6 cycles), treatment delay (≥3 days off-schedule ≥3 times), and/or dose reduction (relative dose intensity≤0.70, based on planned treatment).
Results
Average age at diagnosis was 58.7 years, body surface area (BSA) was 1.9 m2, and body mass index was 28.7 kg/m2. Compared to the highest sex-specific tertile of muscle, patients in the lowest tertile were more likely to experience toxicities had twice the risk of adverse outcomes on FOLFOX: odds ratios (OR) and 95% Confidence Intervals (95%CI) were OR=2.34 (95%CI: 1.04, 5.24; p-trend=0.03) for early discontinuation, OR=2.24 (95%CI: 1.37, 3.66; p-trend=0.002) for treatment delay and OR=2.28 (95%CI: 1.19, 4.36; p-trend=0.01) for dose reduction.
Conclusions
Lower muscle mass is associated with greater toxicity and poor chemotherapy adherence on FOLFOX. Many chemotherapy drugs are dosed on BSA: treatment may be better individualized if muscle mass is considered.