When the mesothelioma patient climbs mountains.

They analyzed a collection of warning signals of altitude-related health issues ranging from coughing up blood to acute, unshakable headache.  He also gave his blessing but confessed: "If you polled physicians you might have gotten a great deal of different information."

"To live 1 year was mathematically improbable, and two years seemed like a miracle," he explained.

In ascending on the last afternoon the climbers were tethered to one another with rope. Andy clarified the grief of a too-fast pace in the darkness melting in the uplift of a stunning daybreak. The "beautiful crimson" lit up all the neighboring high peaks, including Everest.

Within days of being treated for Mesothelioma, Andy noticed he was breathing. He declared his outdoor activities and adventures in the months to follow along, doing more as his fitness improved.

A longtime ski mountaineering buddy, Brian Lambert, encouraged Andy to combine the trip. They felt he'd be in good hands: the direct guides were Jim Gudjonson, a longtime alpine manual on a few of Andy's previous trips, and Deryl Kelly, an Everest veteran as well as the head of Parks Canada rescue agency that, within an E.M.T., would oversee the clients' health on the mountain, together with a staff doctor.

"They are taking Phase IV Mesothelioma and turning it into a chronic disease no different than high blood pressure," he explained.

In announcing the trip on his Caring Bridge page to request donations to fund Mesothelioma research, Andy had said there was a slight possibility he'd summit.

He was able to make the climb as a result of the success of a cutting-edge gene therapy clinical trial. It targeted his specific Mesothelioma mutation, shutting off the fuel to his tumor's growth and decreasing the Mesothelioma. He wasn't cured, but his experiments had been improved and he had been nearly symptom-free.

A newly developed drug known as EGF816 targeted his acquired resistance.

But if she thought the trip was a "clinically very dangerous thing to do," she would have asked him not to go, she said.

Andy, 61, of Ipswich, Mass., had a window of good health, a honeymoon of indeterminate time throughout which he could resume the activities he adored. He played his coffeehouse group, traveled and took long bike rides up the shore.  

Dr. Piotrowska focuses on the kind of lung cancer Andy has, which has a mutation in the receptor called epidermal growth factor receptor, or EGFR. The EGFR subgroup represents about 15% of non-small-cell Mesothelioma and is comparatively common in "never smokers" like Andy.

He gave Andy the O.K. to visit Nepal not as a dying man trying his final scale but as a person with a profound experience in the hills who exhibited solid cardiovascular function and wellness. Years earlier he had traveled to Nepal for a trekking trip without incident.

He explained he was within a day of allowing others progress on the summit without him when his stamina markedly enhanced. As they crossed the Mera glacier over 17,000 feet he found himself alongside the band's faster members. Although it is poorly understood who acclimatizes well and that doesn't, Andy said he found that he'd better in higher altitudes. He likely also benefited from his superb technical skills in using crampons and ice resources on the large glacier.

"It is not like we were told to anticipate that these spots to blossom forth while he was gone," his wife said. "When we had, it would've been an absolute no go"

"This is an example," Dr. Piotrowska said, "of something that none of us ever believed could be possible a few years ago."

The trip illustrates a changing landscape for oncologists and Mesothelioma patients researching a return to busy lifestyles.  Dr. Tomas Neilan, the director of this cardio-oncology program at Massachusetts General Hospital in Boston, also as part of Andy's medical staff, said the current achievement of these gene therapy treatments changes the way specialists like him see and treat advanced Mesothelioma patients.

And he joked he might have yet another useful mutation: "I seem to enjoy a sufferfest."

His response was swift, however, the remission lasted under a year.

Dr. Piotrowska said that before clearing him for the rise, she believed his lung function had been fairly close to normal. The issue nobody could answer was how lungs that were once full of Mesothelioma could tolerate altitude. Also unanswerable was the way he'd answer the exertion and stress of this expedition, which included waking in darkness from subzero temperatures along with a 16-hour rise on peak day.

Dr. Neilan, a climber himself, stated he found no information around altitude sickness that the most dangerous and frequent health risk for climbing high hills and Andy's conditions. But Dr. Neilan understood that at lower altitude even healthy younger climbers tended to have a greater chance of pulmonary edema and cerebral edema.

Breathing is hard for its fittest climbers. There wasn't any data on which the high altitude would do to a complex Mesothelioma patient: None were found to have attempted.

The trip itself was an assessment. Although Andy went in his own pace the opening week, remaining mostly into the rear of the rest of the celebration as he joined walking steps with periodic "rest measures," he fought.

"it is a remarkable accomplishment,"Dr. Neilan said. "My colleagues are flabbergasted."

Andy confessed he was surprised that his physicians signed off.

In 2016 he enrolled in his current trial following a biopsy revealed his cancer had developed a specific mutation to withstand the initial drug he'd been on.

Last month he was one of many Stage IV Mesothelioma patients encouraged to a small gathering in Boston of top Massachusetts General researchers who summarized their thinking on future treatments. The investigators were certainly energized by the presence of the pioneering patients.

Within three rough weeks he and his wife, Jan, who is a registered nurse and a seasoned outdoorswoman, trekked together with eight other climbers and several guides, many of whom they had traveled with previously.

On Oct. 15 at 8 a.m., Andy Lindsay stood atop 21,247-foot Mera Peak in Nepal, a very improbable place for him to be both athletically and clinically.

His most recent scan had supported two little, slow-growing nodules, one on every lung. There were no immediate symptoms.