BCG vaccination and the subsequent development of cancer in humans.

In 1950 approximately one-half of the population of Muscogee County, Georgia, and Russell County, Alabama, who were over the age of 5 years took part in a tuberculosis survey that included a controlled trial of BCG vaccination. A total of 16,913 persons were classed as vaccinees and 17,854 as controls. By the end of 1977, nearly 28 years later, 423 controls and 429 vaccinees were known to have developed cancer. Inasmuch as only 379 cancer cases were expected among vaccinees, there was no indication of any general protective effect of BCG vaccination against cancer. There were 18 sites with 5 or more cancers among controls and vaccinees and with observed/expected ratios greater than 1.49 or less than 0.68. Fewer cancers among vaccinees than expected were found for only 6 of these 18 sites. Among the sites with excessive cases among vaccinees was the lymphoma-Hodgkin's disease-leukemia group [International Classification of Diseases (Eighth Revision) codes 200-202, 204-207], a group suspected from previous studies of occurring more frequently after BCG vaccination.