Before drugs in the United States can be prescribed by doctors and bought by patients, they must undergo three stages of rigorous clinical trials and approval by the Food and Drug Administration. This safety requirement dates back to 1962, when the sedative thalidomide was revealed to have caused thousands of birth defects. This policy has helped cause drug-development costs to skyrocket to hundreds of millions of dollars and drug approval to take up to 10 years, but it has also protected the public from untold risks and side effects.

Circumventing the deliberate pace of clinical trials can be dangerous, as my own father’s story attests. Short of breath for years and told he had asthma, he actually had idiopathic pulmonary fibrosis, a disease in which the lungs quickly and fatally scar. The New England Journal of Medicine reported that interferon gamma-1B could help, but the 1999 report included only nine treated patients. The F.D.A. approved the drug a few years earlier, but for only a rare genetic bone disease or an immune-system disorder, and it could cost tens of thousands of dollars for a course of treatment. My sister and I, both doctors, wrote a letter to my father’s insurer pleading for them to cover this off-label use. Amazingly, the insurer agreed.

Three times a week, my father gave himself an injection of interferon gamma. Not only did the drug not improve his condition, but it also caused raging fevers that left him confined to bed in terrible pain. He died in 2001. Three years later, N.E.J.M. published a far more thorough study with 330 patients that concluded interferon gamma was not only ineffective against the scarring disease but also caused respiratory infections. It would have been better if my father never took it. And because we had found a backdoor way of getting it — he never joined any study — no drug company or regulator learned anything constructive from his death.

Consider what might have happened if more people with idiopathic pulmonary fibrosis followed my father’s path: 330 people may never have enrolled in the study that clearly showed that the drug was useless for his condition. Which is why last year, after the journal Science reported that the drug Targretin, already approved to treat skin cancer, reversed Alzheimer’s disease in mice within three days, federal experts writing in N.E.J.M. warned that “even if patients and families are willing to take the risks [of Targretin] for the potential benefit, the physician’s answer should be no.” Doctors, in other words, should instead tell patients to enroll in placebo-controlled trials, not least so we can learn whether Targretin really helps fight the disease.

Nevertheless, for desperate patients like Broom, the pace of clinical trials can be lethally slow, and patients have successfully argued for “compassionate access” to unapproved drugs. The first compassionate access was granted for a drug called AZT, originally created to treat leukemia, then shelved. In 1985, the Burroughs Wellcome lab sent it to the National Cancer Institute, where, incidentally, Chabner was director of the treatment division. AZT was the 11th drug tested in a shotgun approach against a new virus soon known as H.I.V., and it worked. By 1986, a key study showed the drug saved lives, but final F.D.A. approval would normally take a year. Dying AIDS patients couldn’t wait. So Robert Yarchoan, along with other N.C.I. investigators who helped develop AZT, worked with Wellcome, the F.D.A. and other federal agencies to create an “open-access clinical trial,” which served as a way to release the drug free to almost one-third of all AIDS sufferers in the country. It was a shrewd way to bypass the usual F.D.A. timeline for drug approval.

Pushed by the advocacy group Act Up, the F.D.A. agreed to allow pharmaceutical companies to offer compassionate access to other promising AIDS drugs. The activists for patients with Alzheimer’s and cancer soon demanded access to promising drugs as well. “AIDS created a terrible, wonderful model for us all,” one activist told The New York Times in 1991. In 1999, a 19-year-old college student named Abigail Burroughs unsuccessfully fought for compassionate access to experimental drugs owned by ImClone and AstraZeneca to treat her head-and-neck cancer. After her death in 2001, her father founded the Abigail Alliance, which sued the F.D.A., arguing for a constitutional right to early-phase drugs. Though the courts ultimately ruled against the family, the F.D.A. did recently create a program that would make it easier for companies to release experimental medicines — if the companies agreed to do it.

But not all companies willingly allow compassionate access to drugs in their pipelines, and ImClone’s and AstraZeneca’s reluctance makes sense on some level. Only 6 percent of early-stage cancer drugs ever come to market, because many are found to have severe side effects or simply don’t work. Given those odds, companies hesitate to do anything to jeopardize a product too soon. If they give drugs away, a disastrous side effect or other poor outcome could spur bad publicity and extra scrutiny from regulators. Even more important, if doctors simply let people take untested medicines without going through all the clinical trials, drug companies would most likely never get anyone to enroll in them, never get the data on safety and efficacy for F.D.A. approval and never pass the gateway to big sales. “Even if patients with cancer are willing buyers,” writes George Annas, a Boston University expert on medical law, “drug manufacturers are not willing sellers.”