[Latent heterogeneity of prognosis among cancer patients]

There is a considerable variation in individual lifespan among cancer patients with identical diagnosis. We used damped exponential approximation, which includes both single- and double-compartment extension, for radiobiological assessment of survival curves among cases of breast, lung and oro-pharyngeal cancer. It was shown that in certain cases (breast--T2N1-2M0T3N1-2M0 and oro-pharyngeal cancer--T2-4N1-3M0) the curves can be identified with the two compartments which in turn are associated with different rates of mortality. The remaining curves represented either the slow rate (breast cancer--T1N1-2M0) or the fast one (non-small lung cancer) alone. The mean values of the fast or slow mortality differed 7-fold with high probability; they were stable and almost independent of tumor site or therapeutic modality. The double-rate curves pointed to a possible wide range of prognosis prior to treatment.