Question: What do all these cancers have in common: melanoma, lung, kidney, bladder, ovarian, head and neck, Hodgkin lymphoma, stomach, breast (and others)?

Answer: They have all shown evidence of meaningful, durable responses when treated with one or more of the new immunotherapy drugs. And that is truly amazing, not to mention very unexpected, even by the experts who know this stuff.

That’s the message that is coming out of the 2015 annual scientific meeting of the American Society of Clinical Oncology, where thousands of doctors, researchers and others from around the world make the annual trek to Chicago to share and learn the latest advances in cancer treatment.

The journey to this point has been fascinating.

I personally had some interests in immunotherapy research back in the 1970’s when I was at the National Cancer Institute. We knew that our bodies’ immune systems could recognize some cancers as “foreign,” particularly melanoma and kidney cancer. Even though we had evidence that our bodies could recognize these cancer cells weren’t normal, our natural, “built-in” defense systems sometimes didn’t attack those cancers. The goal was to figure out how to make the immune system wake up and do its job. We did some pretty crude things to people back then, all in the name of trying to make our bodies do what they were designed to do, namely “attack” cancer cells that didn’t belong there just like they attack viruses that infect us.

It was truly a great dream with great promise, but there was little success to show for all the efforts that went into immunotherapy research for decade after decade.

Yet here we are. And we are here big time.

Now at this meeting we have evidence that certain types of colon cancer respond to immunotherapy. Non-small cell lung cancer, the most common type of lung cancer, responds to immunotherapy. Liver cancer, a notoriously difficult cancer to treat, responds to immunotherapy. As for lung cancer, one noted expert said that in his opinion immunotherapy is a new standard of care in the treatment of advanced lung cancer, notwithstanding that we still have much to learn about how to best use this valuable new treatment in this setting.

Who would have thought? Not me, and not many others.

At one of the conference keynote lectures this morning, Dr. Susanne Topalian, who is the director of the melanoma program at Johns Hopkins in Baltimore, shared her memories of a discussion with her father while she was in medical school in the 1970s. She recalled how she explained to her dad that cancer was actually many different, complex diseases. To which he responded that it really couldn’t be that complex. All we had to do was find the common mechanism that all cancers shared and fix it. Needless to say, Dr. Topalian probably thought her dad just didn’t get it.

Today, 40 years later, Dr. Topalian acknowledged that maybe her father’s prediction has come true. Immunotherapy — turning on our body’s ability to recognize and destroy cancers — may be the tie that binds for many different cancers and appears to have the promise to improve the lives of untold numbers of patients.

My past experience at these meetings has always made me just a bit more cautious than many of my colleagues when it comes to claims of breakthrough treatments that will answer our prayers. I have seen too many promising treatments turn out to be less that promised. We have been seduced in the not-so-distant past by the successes of drugs like Gleevec (used to treat chronic myelogenous leukemia and other cancers) and Herceptin (used to treat breast cancer) to believe (hope?) that our new targeted therapies would be the answer we have been seeking for so long to make our patients’ lives better. And time has taught us that although the more recently developed targeted therapies are effective, and some patients do have long, meaningful response, the reality for most is that those responses don’t last long enough.

The initial excitement about so many cancer discoveries has frequently given way to the sobering reality that cancer is smarter than we are.  Now maybe it is our turn to be smarter than the cancer.

However, I must ask the question once again: Is it really different this time? Clearly, based on the discussions at this meeting, many knowledgeable experts think it is.

It’s hard to remain skeptical or cautious about the impact of immunotherapy when confronted with the information being presented at past and current ASCO meetings. As Dr. Topalian commented, it is time to add immunotherapy to its rightful place as one of the pillars of cancer care, next to the more traditional standbys of surgery, chemotherapy, and radiation therapy.

Helping our bodies do what they do best and attack cancer cells that don’t belong inside us has certainly been a long time coming. There is no denying the time is here. And Dr. Topalian’s dad? He was obviously very prescient man.

J. Leonard Lichtenfeld is deputy chief medical officer, American Cancer Society. He blogs at Dr. Len’s Cancer Blog.