‘BCG to the rescue’
A report on a 60-year follow-up of a clinical trial suggests that receiving BCG vaccination during early childhood is associated with reduced risk of subsequent lung cancer development. The results were published in the ‘Journal of the American Medical Association'(JAMA).
The study, “Association of Bacille Calmette-Guerin Vaccination in Childhood with Subsequent Cancer,” was led by researchers at the Uniformed Services University of the Health Sciences (USU) in collaboration with Walter Reed National Military Medical Center, the University of Pittsburgh, Johns Hopkins University, and Cornell University.
In this 60-year follow-up of a clinical trial of the BCG vaccine that included 2963 participants vaccinated at a median age of 8 years, those who received the BCG vaccine had a subsequent lung cancer rate of 18.2 cases per 100 000 person-years. Participants who received the placebo had a lung cancer rate of 45.4 cases per 100 000 person-years. The original study was conducted at nine sites in five US states between December 1935 and December 1998. The trial included 2963 American Indian and Alaska Native schoolchildren younger than 20 years with no evidence of previous tuberculosis infection. In an attempt to ascertain whether the BCG vaccination was associated with cancer tests in a secondary analysis of a trial, the researchers then conducted a 60-year-follow up trial in which participants were assigned to the vaccine group by systematic stratification by the school district, age, and sex, then randomized by alternation. The statistical analysis was conducted between August 2018 and July 2019.
The BCG vaccine is currently the only approved tuberculosis vaccine and is widely administered worldwide, usually during infancy. Previous studies found increased rates of lymphoma and leukaemia in BCG-vaccinated populations. The results and conclusion of the study were as follows:
Results of the Study:
A total of 2963 participants, including 1540 in the BCG vaccine group and 1423 in the placebo group, remained after exclusions. Vaccination occurred at a median (interquartile range) age of 8 (5-11) years; 805 participants (52%) in the BCG group and 710 (50%) in the placebo group were female. At the time of follow-up, 97 participants (7%) in the placebo group and 106 participants (7%) in the BCG vaccine group could not be located; total mortality was 633 participants (44%) in the placebo group and 632 participants (41%) in the BCG group. The overall rate of cancer diagnosis was not significantly different in BCG vaccine vs placebo recipients (hazard ratio, 0.82; 95% CI, 0.66-1.02), including for lymphoma and leukaemia. The rate of lung cancer was significantly lower in BCG vs placebo recipients (18.2 vs 45.4 cases per 100 000 person-years; hazard ratio, 0.38; 95% CI, 0.20-0.74; P = .005), controlling for sex, region, alcohol overuse, smoking, and tuberculosis.
Conclusions and Relevance:
Childhood BCG vaccination was associated with a lower risk of lung cancer development in American Indian and Alaska Native populations. This finding has potentially important health implications given the high mortality rate associated with lung cancer and the availability of low-cost BCG vaccines.
Source: Medical Dialogues, Newswise.com
Usher NT, Chang S, Howard RS, et al. Association of BCG Vaccination in Childhood With Subsequent Cancer Diagnoses: A 60-Year Follow-up of a Clinical Trial. JAMA Netw Open. Published online September 25, 20192(9):e1912014. doi:10.1001/jamanetworkopen.2019.12014