Prevalence of BRCA mutations in an unselected population of triple-negative breast cancer.

BACKGROUND: This study assessed BRCA1 and BRCA2 mutation prevalence in an unselected cohort of patients with triple-negative breast cancer (BC). METHODS: One hundred ninety-nine patients were enrolled. Triple negativity was defined as <1% estrogen and progesterone staining by immunohistochemistry and HER-2/neu not overexpressed by fluorescence in situ hybridization. Having given consent, patients had BRCA1 and BRCA2 full sequencing and large rearrangement analysis. Mutation prevalence was assessed among the triple-negative BC patients and the subset of patients without a family history of breast/ovarian cancer. Independent pathological review was completed on 50 patients. RESULTS: Twenty-one deleterious BRCA mutations were identified--13 in BRCA1 and 8 in BRCA2 (prevalence, 10.6%). In 153 patients (76.9%) without significant family history (first-degree or second-degree relatives with BC aged <50 years or ovarian cancer at any age), 8 (5.2%) mutations were found. By using prior National Comprehensive Cancer Network (NCCN) guidelines recommending testing for triple-negative BC patients aged <45 years, 4 of 21 mutations (19%) would have been missed. Two of 21 mutations (10%) would have been missed using updated NCCN guidelines recommending testing for triple-negative BC patients aged <60 years. CONCLUSIONS: The observed mutation rate was significantly higher (P = .0005) than expected based on previously established prevalence tables among patients unselected for pathology. BRCA1 mutation prevalence was lower, and BRCA2 mutation prevalence was higher, than previously described. Additional mutation carriers would have met new NCCN testing guidelines, underscoring the value of the updated criteria. Study data suggest that by increasing the age limit to 65 years, all carriers would have been identified.

Modeling the 5-fluorouracil area under the curve versus dose relationship to develop a pharmacokinetic dosing algorithm for colorectal cancer patients receiving FOLFOX6.

BACKGROUND: 5-Fluorouracil (5-FU) is administered based on standard body surface area (BSA) dosing. BSA administration results in highly variable exposure, measured as the area under the concentration-time curve (AUC). An immunoassay (OnDose®; Myriad Genetic Laboratories, Inc., Salt Lake City, UT) that measures plasma 5-FU concentration and reports an AUC in mg · h/L has been developed to optimize therapy using pharmacokinetic (PK) dosing. The results of an analysis to model the 5-FU AUC-dose relationship are presented. METHODS: A set of 589 sequential patients from a clinical database receiving 5-FU, leucovorin, and oxaliplatin (the FOLFOX6 regimen) for colorectal cancer (CRC) treatment was analyzed. A subset including only patients who had at least two consecutive cycles tested, received 1,600-3,600 mg/m2 of continuous infusion 5-FU during the initial test cycle, and had a blood sample collected after ≥18 hours, was used to conduct regression modeling of the change in AUC versus change in dose. RESULTS: A simple regression model with R(2) = 0.51 developed over n = 307 cycle-pair observations characterizes the AUC-Dose relationship as: change in AUC = 0.02063 * dose change. The model suggests that dose changes in the range of 145-727 mg/m2 would be sufficient to adjust the AUC to a potential therapeutic threshold of >20 mg · h/L for most patients. CONCLUSIONS: 5-FU is an ideal candidate for PK dose optimization. Because individual factors other than dose change may also affect the change in AUC, longitudinal PK monitoring in all cycles and dose adjustment to ensure AUC in the desired range of 20-30 mg · h/L are recommended.