Bacillus Calmette-Guérin vaccination and cancer prevention: a critical review of the human experience.

Published studies of the cancer experiences of children vaccinated with Bacillus Calmette-Guérin in antituberculosis programs were reviewed and the strengths and weaknesses of each evaluated. There is little evidence that vaccination outside of the neonatal period is effective. If there is an effect of neonatal vaccination, it must convey only a small amount of "protection." Follow-up studies adequate to assess the long-term effects of such vaccination, particularly the risk of lymphoma, have not been done, and recent evidence indicates that such evaluation is warranted.