Immunotherapy: Pros and cons of treating cancer
Dr. Oliver Sartor has a provocative question for patients who are running out of time.
Most are dying of prostate cancer. They have tried every standard treatment, to no avail. New immunotherapy drugs, which can work miracles against a few types of cancer, are not known to work for this kind. Still, Dr. Sartor, assistant dean for oncology at Tulane Medical School, asks a diplomatic version of this: Do you want to try an immunotherapy drug before you die?
The chance such a drug will help is vanishingly small — but not zero. “Under rules of desperation oncology, you engage in a different kind of oncology than the rational guideline thought,” Dr. Sartor said. The promise has drawn cancer specialists into a conundrum. When the drugs work, a cancer may seem to melt away overnight. But little is known about which patients might benefit, and from which drugs.
Some oncologists choose not to mention immunotherapy to dying patients, arguing that scientists first must gather rigorous evidence about the benefits and pitfalls, and that treating patients experimentally outside a clinical trial is perilous business. But others, like Dr. Sartor, are offering the drugs to some terminal patients as a roll of the dice. If the patient is dying and there’s a remote chance the drug will help, then why not? “Immunotherapy is a particularly nuanced problem,” said Dr. Paul Helft, oncologist at Indiana University School of Medicine.
Cancer doctors are well aware of the pitfalls of treating patients before all the evidence is in. Many still shudder at the fiasco that unfolded in the 1980s and 1990s, when doctors started giving women with breast cancer extremely high doses of chemotherapy and radiation on the theory that more must be better. The doctors did not systematically collect data; instead, they reported patient anecdotes claiming success.
Then a clinical trial found that this treatment was much worse than the conventional one — the cancers remained just as deadly when treated with high doses, and the regimen itself killed or maimed women.
But immunotherapy is like no cancer treatment ever seen. It can work no matter what kind of tumor a person has. All that matters is that the immune system be trained to see the tumor as a foreign invader.
Tumors have mutations that stud them with bizarre proteins. The white blood cells of the immune system try to attack but are repelled by a molecular shield created by the tumors. The new drugs allow white blood cells to pierce that shield and destroy the tumors.
Last week brought a yet another example of the surprising power of this approach. Lung cancer patients who normally would receive only chemotherapy lived longer when immunotherapy was added, researchers reported in a clinical trial.
Immunotherapy drugs can have severe side effects that can even lead to death. Once the immune system is activated, it may attack normal tissues as well as tumors. The result can be holes in the intestines, liver failure, nerve damage, serious rashes and eye problems, and problems with the pituitary, adrenal or thyroid glands. Side effects can arise during treatment or after the treatment is finished.
For most patients, though, there are no side effects or only minor ones. That makes giving an immunotherapy drug to a dying patient different from trying a harsh experimental chemotherapy or a treatment like intense radiation.