It offers a form of chemotherapy originally called "antineoplaston therapy" devised by the clinic's founder Stanislaw Burzynski in the 1970s.

There is no accepted scientific evidence of benefit from antineoplaston combinations for various diseases, and the Clinic's claimed successes have not been replicated by independent researchers.

[2] The therapy is administered through the ruse of running a large numbers of clinical trials, which long-time Burzynski lawyer Richard Jaffe has described as "a joke".

Burzynski claims this degree was a Ph.D. in biochemistry, but cancer researcher Saul Green found evidence indicating he received a D.Msc.

This opened him up to "charges of unethical conduct and to the suspicion he had become a merchant of false hope", which led to several instances of media controversy.

"[20] Although the therapy is promoted as natural and benign, it is in reality a form of chemotherapy with harmful side effects including severe neurotoxicity.

[21][22][7] Burzynski stated that he began investigating the use of antineoplastons after detecting what he considered significant differences in the presence of peptides between the blood of cancer patients and a control group.

David Gorski argues that the concept of "personalised cancer therapy" is "more of a marketing term than a scientifically meaningful description".

Jaffe wrote that CAN-1 was "a joke" of a clinical trial and explained the legal maneuvering: The CAN-1 protocol had almost two hundred patients in it and there were at least a dozen different types of cancers being treated.

[29][35][32] Independent scientists have been unable to reproduce the positive results reported in Burzynski's studies: NCI observed that researchers other than Burzynski and his associates have not been successful in duplicating his results,[29] and Cancer Research UK states that "available scientific evidence does not support claims that antineoplaston therapy is effective in treating or preventing cancer.

[12] In 1998, three oncologists were enlisted by the weekly Washington newsletter The Cancer Letter to conduct independent reviews of Burzynski's clinical trial research on antineoplastons.

[38] In addition to questioning Burzynski's research methods, the oncologists found significant and possibly life-threatening toxicity in some patients treated with antineoplastons.

"[40] Recent criticism has focused on the use of crowdfunding to raise the costs of quack treatments, including specifically hundreds of thousands of dollars in the case of the Burzynski Clinic.

[41][42][43][44] In 1978, FDA representatives warned Burzynski that he was violating federal law because he was not administering antineoplastons in the context of a clinical trial.

[...] Since Antineoplastons are investigational new drugs, the products' indication(s), warnings, precautions, adverse reactions, and dosage and administration have not been established and are unknown at this time.

In December 2013, the FDA issued its findings in warning letters to Burzynski, expressing "concerns about subject safety and data integrity, as well as concerns about the adequacy of safeguards in place at your site to protect patients...."[50] In November 2013 the FDA released the observational notes from an inspection of Burzynski as a principal investigator that took place between January and March 2013.

Among the findings were "[failure] to comply with protocol requirements related to the primary outcome, therapeutic response [...], for 67% of study subjects reviewed during the inspection", admitting patients who failed to meet inclusion criteria, failing to stop treatment when patients had severe toxic reactions to antineoplastons, and failure to report all adverse events.

Forty-eight (48) subjects experienced 102 investigational overdoses between January 1, 2005 and February 22, 2013 [...] There is no documentation to show that you have implemented corrective actions during this time period to ensure the safety and welfare of subjects.” The FDA also observed that Burzynski had denied patients informed consent by not informing them of extra costs that they might incur during treatment and that he could not account for his stock of the investigational drug.

[55] David Gorski wrote in 2014 that over four decades the FDA and state medical boards have been unable to shut down Burzynkski's business selling unproven treatments – "these organizations are supposed to protect the public from practitioners like Burzynski, but all too often they fail at their charges, in this case spectacularly.

According to an investigative report by STAT News published in August 2016, the clinic has benefited by politicians who lobbied the FDA to allow Burzynski to sell antineoplastons to families of patients with terminal diagnoses.

[...] Most of the lawmakers asked the agency to grant constituents 'compassionate use exemptions' so that they could try his unapproved drugs, or to allow his clinical trials to proceed.

"[56] According to STAT, critics state that "the congressional advocacy risks giving the terminally ill and their families a false sense of hope, while also conferring a measure of legitimacy on him that many believe he does not deserve.

[68] In 1983, a federal court issued an injunction against Burzynski, barring him from shipping antineoplastons in interstate commerce without FDA approval.

An administrative law judge ruled that Burzynski violated a section of the Texas Health and Safety Code dealing with prescriptions for unapproved drugs.

[77] In January 2012, Lola Quinlan, an elderly, stage IV cancer patient, sued Burzynski for using false and misleading tactics to "swindle her out of $100,000".

[79][80] In November 2011, a music writer and editor for the British newspaper The Observer sought help raising £200,000 to have his 4-year-old niece, who was diagnosed with glioma, treated at the Burzynski Clinic.

[84] One of the bloggers who received threatening e-mails from Stephens was Rhys Morgan,[85][86][87][88] a 17-year-old sixth-form student from Cardiff, Wales, at the time, previously noted for exposing the Miracle Mineral Supplement.

The chief clinician at Cancer Research UK expressed his concern at the treatment offered, and Andy Lewis of Quackometer and science writer Simon Singh, who had previously been sued by the British Chiropractic Association, said that English libel law harms public discussion of science and medicine, and thus public health.

He claimed aggressive actions by Burzynski's supporters toward the critics, including contacting their employers, lodging complaints to state licensing boards and defamation.

Blaskiewicz pointedly indicated that, although Burzynski had dismissed Marc Stephens, his clinic has not retracted the warnings of the possibility of lawsuits against critics, that it is "a threat that hangs over all of these activists every day".