Impact of improved local control on survival.

Estimates of the gain in survival, if all local failures were eliminated, indicate that many more patients could be cured provided the efficacy of treatment of the primary and regional disease were substantially improved. The expected gain in survival is assumed to be the gain in local control, less the loss due to distant metastases and intercurrent disease among the new local control subjects. The observed incidence of DM among local failure patients may be higher than among local control patients; this excess in incidence of DM is assumed to result from metastases established secondary to the persistent or recurring tumor. A powerful argument that higher local control rates would result in more cured patients is the high incidence of long-term survivors after salvage surgery for local failures. Examples of higher survival associated with more effective local therapy are presented from the literature for medulloblastoma, ependymoma, carcinoma of the oral cavity-oropharynx, carcinoma of the urinary bladder, carcinoma of the prostate and carcinoma of the rectum. For Stage I-II cancer of the breast, the reduction of an already low local failure rate by combining surgery and radiation has a very small impact. For tumors, such as, early stage breast cancer, where the possible decrease in local failure is small and the loss due to DM is high, a demonstrable gain in survival is not likely. The potential increase in number of survivors among the U.S. cancer population, if the primary-regional disease were regularly treated successfully, indicates large gains for patients with cancer of the uterine cervix, oral cavity-oropharynx, ovary, colo-rectum, non-oat cell cancer of lung, prostate cancer, and bladder cancer. These provide powerful bases for aggressive investigation of new approaches to improvement of local-regional therapies.