A leading British cancer specialist has urged Members of Parliament to investigate apparent links between repeated mRNA COVID-19 booster doses and unexpected cancer relapses among long-stable patients.
Professor Angus Dalgleish, former foundation chair of oncology at St George’s, University of London, delivered his warning last week to the All-Party Parliamentary Group (APPG) on Pandemic Response and Recovery. According to Dalgleish, six of his patients with advanced melanoma—whose disease had remained dormant for between three and 18 years—experienced sudden and aggressive relapses within weeks of receiving their third or subsequent COVID-19 booster shots in late 2021 and early 2022.
“The only common factor we could find was the booster,” Dalgleish told MPs. “These patients had been stable for years. The relapses required urgent new treatment.”
He explained that laboratory analyses revealed signs of T-cell exhaustion, a suppression of the immune response that normally restrains cancer growth. Dalgleish suggested that repeated boosters, rather than the initial two vaccine doses, could induce this effect in some individuals.
The oncologist also raised questions about the potential for mRNA to integrate into human DNA and interfere with normal cellular regulation—claims that remain controversial and are disputed by regulatory agencies and mainstream immunologists.
“In my opinion, this is no longer a hypothesis. The data are in. The mechanisms are understood,” said Dalgleish. “The signal is screaming. It is time to act.”
The Medicines and Healthcare products Regulatory Agency (MHRA) has maintained there is no causal evidence connecting mRNA vaccines to cancer onset or relapse. In a statement, it reiterated that “the benefits of vaccination in preventing severe COVID-19 far outweigh any potential risks,” and highlighted extensive population studies showing no consistent rise in cancer incidence among vaccinated groups.
Still, Dalgleish’s testimony aligns with concerns raised by some clinicians abroad. Population-level analyses from South Korea and Italy have reported statistical associations between vaccination rates and certain cancer trends, though those studies do not establish causation and have been challenged by epidemiologists for possible confounding factors.
APPG chair Esther McVey described the claims as “deeply unsettling,” adding that Parliament “must ensure data transparency and support independent review.” Fellow MP Graham Stringer called for urgent research into long-term effects of mRNA vaccines, noting that “carcinogenicity studies were not conducted prior to emergency authorization.”
While officials stress the vaccines’ role in saving millions of lives, Dalgleish insists the emerging signals warrant investigation rather than dismissal. “This is no longer a hypothesis,” he said. “The data need to be confronted openly to protect patient safety.”
The MHRA has pledged to review any new evidence submitted to its safety monitoring system. Public health authorities continue to recommend vaccination, but have encouraged physicians to report all unexpected post-vaccination clinical developments to ensure ongoing evaluation.
