For survival data with a cure fraction, we propose a general semiparametric model which is derived from the biological process of cancer-relapse mechanism and includes both the mixture cure models and promotion time cure models as two special cases. The pseudo integrated least squares estimators (PILSEs) of index coefficients are shown to be consistent and asymptotically normal and an efficient computing algorithm is proposed to calculate the PILSEs of index coefficients and the moment-type estimators of promotion time function. Simulation studies are conducted to examine the finite-sample properties of the proposed estimators.