Pharmaceutical Innovation and U.S. Cancer Survival, 1992-2003: Evidence from Linked SEER-MEDSTAT Data

Abstract

This study examines the impact of pharmaceutical innovation and other factors on the survival of U.S. cancer patients during the period 1992-2003. In particular, it investigates whether cancer survival rates increased more for those cancer sites that had the largest increases in the proportion of chemotherapy treatments that were "new" treatments. We control for other types of medical innovation, i.e. other pharmaceutical innovation, and innovation in surgical procedures, diagnostic radiology procedures, and radiation oncology procedures.Data on observed survival rates, the number of people diagnosed, mean age at diagnosis, and stage distribution are obtained from the National Cancer Institute’s SEER public-use data. Estimates of rates of innovation in chemotherapy and other treatment and diagnostic procedures are constructed from the MEDSTAT MarketScan database and other data sources. Treatment innovation indicators based on MEDSTAT data are likely to be useful, albeit noisy, indicators of the treatment innovation experienced by patients in SEER registries. This sampling error is likely to bias the coefficients on the treatment innovation measures towards zero.We compute weighted least-squares estimates of 6 versions of a survival model, based on different survival intervals and functional forms. The chemotherapy vintage coefficient is positive and significant in every model. This indicates that the cancer sites whose chemotherapy vintage (measured by the share of post-1990 treatments) increased the most during the period 1992-2003 tended to have larger increases in observed survival rates, ceteris paribus.We estimate how much lower the survival rate from all cancer sites combined would have been during 1993-2001 in the absence of post-1992 chemotherapy innovation. The estimates indicate that chemotherapy innovation accounted for 74% of the increase in the 1-year observed survival rate for all cancer sites combined during the period 1992-2001. Chemotherapy innovation accounted for smaller fractions of the increases in the 2-year and 3-year observed survival rates for all cancer sites combined during the same period: 51% and 29%, respectively.The coefficients on measures of non-pharmaceutical medical innovation (in radiation oncology, diagnostic radiology, and surgery innovation) are generally not significant. However these measures may be less reliable than the drug innovation measure. They were based upon the year in which the AMA established a new procedure code, which may be a far less meaningful indicator of innovation than the year in which the FDA first approved a drug. This topic warrants further research.