It has been a common notion that cancer patients nearly always die of their primary malignancy. Thus, many authors fail to report, in publications of their experiences, the proportion of patients succumbing to other causes; this may be quite substantial, depending on the type and degree of malignancy, age and sex of the patients, type of treatment, and other factors. For example, the crude survival rate (uncorrected) for deaths due to intercurrent or concurrent diseases or for tumor nonrecurrence, is not a good measure of success of treatment in patients with skin cancer, especially since the patients are elderly, and the cancer is relatively nonlethal and is treated in an early stage. However, in the case of lung cancer, the natural forces of the process are relatively strong, and only a small proportion of patients do not die of this disease. In the latter situation, it is reasonable to assume