Is age-related worsening in ovarian cancer prognosis linked to changes in body composition and pharmacokinetics?

Abstract

e17553 Background: The prognosis of ovarian cancer worsens markedly with age. Yet few data are available to explain this phenomenon. Two hypotheses can be made. Changes in pharmacokinetics and treatment tolerance limit the dosing of chemotherapy. And/or changes in tumor and host-tumor biology limit treatment efficacy. Methods: We conducted a prospective cohort study of women with stage III/IV high-grade serous ovarian cancers treated with neoadjuvant intravenous carboplatin(C) AUC 5 every 3 weeks and paclitaxel(P) dosed either weekly at 80 mg/m2 or every 3 weeks at 175 mg/m2. Body composition was assessed using baseline CT scans at the L3 level. Total muscle mass, total fat mass, skeletal muscle index (SMI) and fat index were computed. Plasma concentrations were collected at pre-established time points for both C1D1 of C and P and concentration-time data was analyzed by non-compartmental methods. Area under the curve (AUC)0-INF, volume of distribution(Vd), clearance (Cl), half-life, and mean residence time were calculated. Free C concentrations were determined in plasma ultrafiltrate and assayed, along with P plasma concentrations, by liquid chromatography-tandem mass spectrometry. Toxicity was assessed as first cycle nadir ANC and G4 hematologic(H) or grade 3-4 non-hematologic(NH) toxicity by CTCAE 4.0 criteria over a 3 cycles follow-up. The correlation between continuous measures was assessed by Spearman correlation coefficient, and the association with toxicity was evaluated by Wilcoxon rank sum test. Results: Seventeen patients, ages 38 to 86 (median 61) were eligible. All patients but one received 3 cycles of chemotherapy and median dose intensity was 100% (range 33.3-100%). Mean 1st cycle nadir ANC was 1.29 (range 0.06-9.0). 10/17 (59%) patients experienced G4 H and/or G3-4 NH toxicity. SMI was associated with C AUC (r -0.50, p < 0.05), and both total muscle (r = 0.61) and total fat (r = 0.53) were associated with C Vd. We did not find a correlation of P pharmacokinetics with body composition. A lower SMI was associated with 1st cycle G4H toxicity (p = 0.02), while C AUC had a borderline trend only (p = 0.15). Age was associated with a lower Vd (r -0.63, p = 0.009) and Cl (r -0.67, p = 0.004) of C. There was no significant age trend in the body composition parameters. Conclusions: Neoadjuvant treatment delivery was high in an academic setting. Toxicity appeared driven by low skeletal muscle index, in part via affecting carboplatin pharmacokinetics, and showed no significant age trend. The explanation for age-related changes in prognosis is more likely to lay with changes in tumor and host-tumor biology, which are being analyzed.