Zhang EW, Dagogo‐Jack I, Kuo A, et al. - Among patients with anaplastic lymphoma kinase (ALK)‐positive lung cancer, researchers evaluated if there was any link between circulating tumor DNA (ctDNA) burden and disease burden. To ascertain ALK and non‐ALK alterations, 97 plasma specimens from 75 patients were analyzed. In nearly 85% of plasma specimens, ctDNA was identified. In 79% of plasma specimens, the presence of an ALK fusion was detected, while in 76% of plasma specimens, an ALK mutation was detected. Involvement of the liver, bones, and adrenal glands, of all the disease sites assessed, was correlated most with ctDNA burden. The extrathoracic burden of disease was associated with the maximum plasma alteration allelic frequency (AF) and maximum ALK alteration AF, which were also found to be more predictive of tumor burden vs the ALK fusion AF alone in patients with ALK‐positive lung cancer.