The investigators will assess metabolomic levels/profile associated with an increased risk of drug dose reduction caused by toxicity with Cox-regression modelling of the number of days of drug treatment until the reduction of dose. Patients with no dose reductions will be censored at final follow-up. For multivariable analysis, the investigators will use clinical factors associated with p<0•1 with dose reductions as covariates, and the investigators will analyse the metabolomic levels associated to drug dose reduction in the multivariable analysis with the Kaplan-Meier method. The investigators will study associations between specific drug toxicities and metabolomic profiles with logistic regression analysis, with toxicity development as a dichotomous endpoint. The multivariable logistic regression analyses will include clinical factors associated with the corresponding outcome as covariates (factors with p<0•1). The investigators will test all genotypes with an additive genetic model. The investigators will retain missing data as missing apart from MSKCC prognostic factors. The most likely value, based on the data from the rest of the series, will be assigned to these patients.