This article was reported and written in a collaboration with ProPublica, the nonprofit investigative journalism organization.

Dr. José Baselga, the chief medical officer of Memorial Sloan Kettering Cancer Center, resigned on Thursday amid reports that he had failed to disclose millions of dollars in payments from health care companies in dozens of research articles.

The revelations about Dr. Baselga’s disclosure lapses, reported by The New York Times and ProPublica last weekend, have rocked Memorial Sloan Kettering, one of the nation’s leading cancer centers, in recent days. Its top executives scrambled to contain the fallout, including urgent meetings of physician leaders and the executive committee of its board of directors.

In his resignation letter released Thursday, Dr. Baselga, who also served as the physician-in-chief, said he feared that the matter would be a distraction from his role overseeing clinical care and that he had been “extremely proud” to work at Memorial Sloan Kettering.