Since my diagnosis in 1994 of a rare, incurable condition--medullary thyroid carcinoma--I've searched for an effective treatment. After three neck operations and chemotherapy did little to check my cancer's spread, I entered a drug trial at Fletcher Allen Health Care in Vermont. The oncologist running the experiment was Dr. Steven Grunberg, who took me under his wing. Despite my aggressive disease, he reassured me with quiet confidence. We're going to help you stick around, he said.Today, thanks to Dr. Grunberg and his staff, I'm still here. But Dr. Grunberg isn't. He died of lung cancer in September. It's a painful irony I'm still sorting through.By the time I found Dr. Grunberg five years ago, my cancer had spread to my lungs. I was growing desperate. In my mid-40s, with many things yet to accomplish in life, I researched experimental treatments and exchanged information with other sufferers of my rare disease through the Thyroid Cancer Survivors' Association.One day I clicked to the clinical trials page of the National Institutes of Health, and learned of a novel drug being tested against my specific condition. The drug, then called Zactima, is a tyrosine kinase inhibitor. Basically it works to block proteins that tell tumors to grow.Vermont's Fletcher Allen Health Care was among the study sites. One weekday morning I drove three hours from my Clifton Park, N.Y., home to Burlington, Vt., to meet Dr. Grunberg and get the ball rolling. Though untested drugs can be risky, he quickly earned my trust. A thick-haired man who spoke in quiet intelligent bursts, he'd keep a close eye on me, monitoring my status through bloodwork and scans. He spoke frankly of possible side effects, which included skin and intestinal problems. There was another concern. Two-thirds of study participants were supplied with the drug--but one-third received a placebo. Neither doctor nor patient knew which one patients had. I could be left without a life preserver.By my next appointment, three months later, my levels of calcitonin--a hormone stimulated by my cancer--crashed to 10,000 from over 100,000 before the trial. It was apparent I was among the lucky two-thirds of patients. The drug was working! Dr. Grunberg wasn't one to show a lot of emotion with me, but he shared an enthusiastic smile when he told me the good news. I immediately called my wife to tell her, and drove back to New York that afternoon, my heart singing with hope for my future.Over the next five years I visited Fletcher Allen every three months. I came to refill my prescription of once-a-day Zactima pills, undergo CT scans and bloodwork -- and to feel supported by Dr. Grunberg and his staff of nurses and researchers. I remember pricking my ears to catch every morsel of what Dr. Grunberg was saying. He was a steadfast presence, and when he examined my neck and chest for recurrence, I was in sure hands.He was more than a doctor to me. As a theater buff, he took an active interest in my writing, and spoke to me of his daughter's creative pursuits. I emailed him several of my short stories, and he always took time to send me a complimentary email back. I considered him a friend.The drug kept my condition at bay, and as a result of the trial was approved as Caprelsa by the Food and Drug Administration for use against my cancer. Today thousands of patients like me can now benefit from work by Dr. Grunberg and other study researchers.The last time I saw Dr. Grunberg was this past spring. I noticed no difference in his manner toward me. He seemed healthy, energetic--his hair as thick and dark as ever. He gave zero hint he had cancer, let alone terminal cancer, even as he treated mine. He betrayed nothing. But when I visited Fletcher Allen again in summer I received the odd news he'd taken a leave. I asked for elaboration but the staff was oddly quiet. It wasn't until I visited again this fall when his staff told me Dr. Grunberg had died of lung cancer.I was stunned. But he didn't seem sick, I insisted. He kept working right up until the end. That's when it hit me: he didn't want his patients to know their doctor was dying of the same condition they hoped to beat. Dr. Grunberg didn't want them to lose hope, even as his own situation grew hopeless. My sense of betrayal at not being told sooner melted away into gratitude. His silence was admirably selfless. The world--my world--is poorer without him.When I revisit Fletcher Allen for my next appointment in January, I'll see another oncologist who has replaced Dr. Grunberg on the trial I'd entered. She's a smart, caring doctor, and I recognize signs of selflessness in her as well, because I now have a standard against which to measure people's worth. Because Dr. Grunberg gave me a new lease on life, even as his own lease expired.David Kalish is a survivor of medullary thyroid carcinoma and the author of the comedic novel, The Opposite of Everything, which inspired this essay and will be published this spring. You can read more at davidkalishwriter.com.