Pancreatic cancer is one of the most lethal human diseases known to man. Each year, more than 40,000 Americans are diagnosed with pancreatic cancer, and 95 percent die within the next 12 months. Steve Jobs, Patrick Swayze, opera singer Luciano Pavarotti: These celebrities all died from pancreatic cancer.

Because survival rates are low, and treatment options are limited and usually ineffective, pancreatic cancer can be deadly to the body and spirit, and considered tantamount to a death sentence. But that doesn’t have to be the case: I survived the most lethal type of this disease— not once, but twice.

Persevering through that second bout— a spread of this cancer to my liver after a long period of remission— is virtually miraculous and defies clear explanation. I have been physically fit and active my entire life, and was treated by superbly trained doctors at one of the best hospitals in America, but so have many others whose lives have been claimed by this horrible ailment.

Those factors undoubtedly helped me beat another round of pancreatic cancer, but, equally important, so did my attitude.

Instead of succumbing to defeat, I made a deliberate decision to stay upbeat during my illness, which was a life-altering challenge amidst my diagnosis and all the brutal treatment, including two major surgeries— one more complex than a heart transplant— experimental radiation, conventional radiation and chemotherapy. I detailed my choice to remain positive while battling cancer in my recently published book, “The Ripple Effect: How a Positive Attitude and a Caring Community Helped Save My Life.”

My wife, Karen, was instrumental in this attitude change. Right before my second diagnosis was confirmed, she reminded me how much we’d been through and how important it was to be as positive as we could to get through everything together with grace. I made it my priority to survive— next, I had to figure out how to move toward this goal.

Figuring out how to stay positive

Up until my cancer diagnosis, I was a generally optimistic person but someone who too often got sidetracked by reacting negatively to the little hurdles we all face in life. But the mortal threat of pancreatic cancer switched me into survival mode, and made me focus all my energy on my wellbeing and on that of my loved ones.

It’s all too common for families struggling to deal with pancreatic cancer— or any hardship— to fall into emotional devastation and poor quality of life. I believed that negative emotions would detract from my support system, making it hard for all of us to fight the disease together.

With my decision to stay upbeat in mind— and thanks to CaringBridge.org, a blog for seriously ill patients and their families to share their stories— we were able to create a spiritually nourishing, healing community of relatives and friends.

During my cancer journey, I could not control the progression of my disease or many of the events that swirled around me. However, I could control or at least deeply impact my reactions. I call this “the power of choice,” and I believe patients can take this route to empower themselves through severe, life-threatening disease and other life challenges. Looking back, I understand that I ultimately made a choice to be a survivor rather than a victim.

Facing the reality of possible death

The earliest test to my positivity came after the surgery, radiation and chemotherapy treatments for my first cancer diagnosis— when a blood marker of tumor cell activity increased, right before my wife and I were about to embark on a cruise to celebrate my completion of chemotherapy.

This event sparked the likelihood of additional treatment and cancellation of our long-planned vacation. More ominously, after all the brutal procedures I’d been through thus far, I had to again face the possibility of premature death.

Karen tried her best to reverse the dent this news had made in my attitude, but I ended up bringing her down too. On the basis of one test result, all the positive energy that had flowed between us during my entire year of treatment quickly became a reciprocal flow of negativity. This experience increased our understanding of the power of positive and negative thinking, and how these attitudes can create either hope or despair.

After a repeat blood test later showed the first result had been a fluke, we were able to enjoy our cruise, which would preface an even greater challenge: potential metastasis of pancreatic cancer to my liver.

Nearly three years after surgery for the tumor in my pancreas, routine surveillance testing showed cancer had spread to my liver. Because pancreatic cancer normally spreads rapidly from this organ, the event is generally not considered survivable.

My doctors initially recommended palliative care. But from knowledge gleaned as a physiologist and medical school professor, I realized there was more they could do, so I requested bold, aggressive, decisive and rapid treatment. This meant tests to detect any spread beyond my liver and, if there was no spread, liver surgery to remove the tumor.

Later, I learned the reason for their reluctance was that no patient at that prestigious hospital had ever survived spread of my type of pancreatic cancer to the liver. Doctors were not optimistic and tried to dissuade me from pursuing aggressive treatment. However, they agreed to meet with a physician group to discuss my options.

After leaving the hospital, fear gripped my family: This was the most immediate mortal threat of my entire cancer experience. With the odds of survival now one in several thousand, the threat to my life was so immediate that mortality dominated my thoughts. In spite of this, my determination to survive was undiminished.

The physician group met and recommended a PET scan to assess any cancer spread from my liver. Based on the scan results, liver surgery would be considered. The scan was scheduled for the following week.

At that time, I was teaching in a medical school on the Caribbean island of St. Maarten and had returned home to Boston between semesters for cancer screening tests. Karen and I were looking at each other with tears and apprehension when she suggested a brilliant distraction: a weekend trip to St. Maarten for the weekend.

After an emotion-packed flight to the island, we enjoyed dinner at our favorite French restaurant, as well as trips to our favorite beach with my medical school friends and colleagues. These revelries helped assuage fears of prospective PET scan results, liver surgery or more chemotherapy.

Amazingly, a few days later, the PET scan provided no evidence that the pancreatic cancer had spread beyond my liver. Even though microscopic activity undetectable by the PET scan could not rule out further cancer spread, my doctors decided to proceed with the liver surgery that saved my life.

Living on the other side of cancer

Today, I am 66 years old, cancer-free, in excellent health and nearly five years past my second bout with pancreatic cancer. I exercise regularly, follow no dietary restrictions and pursue a full-time, demanding career.

I am aware that deadly illnesses such as pancreatic cancer have claimed the lives of many patients with a positive attitude and that staying upbeat itself is not likely to fully substitute excellent medical care. But I can confidently say that a positive attitude helped spare my emotional life and that of my family. Also, by staying positive, I had the wherewithal while recovering from the brutal treatment procedures to think deeply and clearly about a wide variety of life issues. To experience both the lethal disease itself and have ample time for introspection was absolutely life-changing. Because my cancer experience helped me identify what is truly important in life, I now look forward to each day with a sense of vigor that I couldn’t have fathomed before.

I am now, in the fullest sense, a survivor and not a victim. As they say, I don’t sweat the small stuff in life. When something goes wrong that previously would’ve troubled me, I simply say, “It’s not pancreatic cancer, so why worry?” For this reason, my cancer experience, as physically and emotionally perilous is it was, provided me with a great gift: a positive attitude that truly saved my life.

Steven Lewis was born in Brooklyn, New York, and received a Ph.D. in exercise physiology from Stanford University in 1977. He is a visiting professor at the Charles E. Schmidt College of Medicine, Florida Atlantic University, in Boca Raton, Fla. Steven lives in South Florida with Karen, his wife of 44 years, and his dogs, Leeza and Mambo. He is the author of "The Ripple Effect: How a Positive Attitude and a Caring Community Helped Save My Life."