The patients and staff members at Memorial Sloan-Kettering never have a problem spotting D.J. Cohen.

At 39, he’s fighting Stage 4 pancreatic cancer. On any given Monday he may show up outfitted as Darth Vader, or a Pharaoh, or a Coke bottle, or Marvel Comics antihero Deadpool or …

“He’s dressed as Batman today,” says Julian Cazares, who works at the fourth-floor reception desk of the cancer center’s outpatient pavilion, where patients come for chemotherapy.

In a waiting room full of nervous patients and concerned relatives, all dressed appropriately for a hospital setting, Cohen walks around, the object of bemused stares, with a smile on his face and the superhero’s cowl over his head, the costume’s fake muscles expanding his torso. Each week, a different costume.

Cohen’s a familiar sight there, no matter how he’s dressed. “Everyone knows him,” Cazares says.

The fictional characters — and a dress he sometimes drapes over his chemo pole, which he has dubbed “Lolita” — are part of Cohen’s character.

“At 13, I decided I wanted to work on myself,” Cohen says. He took to reading a series of human potential books. “I always asked God: ‘What I am going to do to utilize this information?’”

The answer was cancer.

After receiving a terminal diagnosis on Feb. 27, 2015 — “at 3:30 p.m.,” he says — he’s undergone a regimen of 50-plus chemo treatments, supplemented by daily prayers, meditation, affirmations — and medical marijuana that mitigates the chemo’s side effects. His status now: He’s not in remission, not under hospice treatment, “thank God,” he says.

After developing an allergic reaction eight months into the three-times-a-month treatments, he decided to fight back.

First came Pac-Man — he had envisioned the voracious video game figure as a healthy cell devouring diseased ones. In subsequent weeks he’d don other costumes, his choice depending on his mood. “I think I bought one,” he said. The rest, supportive friends brought him. Probably a few dozen; Cohen hasn’t counted. “We have at least two huge garbage bags filled with costumes,” says his wife Alexis, whom Cohen met on a Birthright Israel trip in 2000.

Regularly indisposed by the side effects of chemo, Cohen has put his sales-and-marketing career on hold, devoting his time to giving motivational speeches. And getting well.

CBS Radio and Cancer Treatment Centers of America recently named him a 2016 “cancer hero.”

“DJ made it his mission … to motivate and inspire anyone facing any type of personal hardship,” states teamdeej.com, the website he set up to update people on his health. Team Deej (pronounced “D-J”) is what he’s named his “tight circle of family and friends.”

In making costumed appearances at chemo sessions, Cohen has joined a growing group of like-minded men and women. A Google search turns up many — pirate costumes are especially popular among men; Wonder Woman, among women.

Cohen, officially known as David J. Cohen, grew up in a family with Syrian Jewish roots on both sides in the Flatbush section of Brooklyn. He’s part of the Sephardic community, which has pitched in since he became sick, bringing the family daily meals, helping his children with homework and putting him on prayer lists.

At Sloan-Kettering, Cohen is never alone. Sometimes up to two dozen people show up, taking shifts in his infusion room.

“You see people here [for treatment] — they come alone,” Cohen says. “It breaks my heart.”

A graduate of Brooklyn’s Yeshivat Magen Abraham and an active member of the Larchwood Avenue Shul in Oakhurst, N.J. (both Syrian-Jewish institutions), Cohen drives from his home near Deal, N.J., on chemo days, and changes into his garb du jour in a parking lot near the East Side pavilion.

Sometimes he brings his guitar — he’s a singer. And a poet, too.

The costumes are a reflection of his upbeat attitude, designed to keep up his spirits, that of his fellow patients’, and especially his family’s.

“I have a wife and three daughters,” he says one recent Monday, sitting in a small infusion room, surrounded by his wife and a half-dozen Team Deej members.

“I want to enjoy myself,” he says. “It really makes me happy to help people.”

Plus, as a parent, he says, “I can’t be depressed.”

“My daughters, when they see me going for chemo, they’re not scared,” he says. Instead they’ll ask, “What costume are you wearing today?”

While he shows signs of “chemo brain,” occasional memory lapses — “It’s real,” he says — he’s relentlessly gregarious. Because of steroid treatments, which commonly cause weight gain, he doesn’t have a cancer patient’s typical gaunt look. After losing his hair, it’s grown back in, including a well-trimmed beard.

A dedicated jogger, he’s taken to the roads again. “I did eight miles on Tuesday,” he says.

To look at Cohen, you’d have no idea that he is sick. Maybe a bit meshugenah.

“This is no joke,” he says in a serious moment. He knows the odds.

Pancreatic cancer, as bad as it gets, has spread to his liver.

About 45,000 people in the United States are diagnosed with pancreatic cancer every year; it’s the fourth leading cause of cancer death in the country, with the shortest median survival rate of any major form of the disease.

“Historically, patients with metastatic pancreatic cancer have been considered incurable and rarely survived more than one year,” according to the cancerconnect.com website.

At 20 months and counting, Cohen has already beaten the odds.

“I’m very lucky,” he says.

When first diagnosed, he sought two more physicians’ opinions. “Each gave me three months,” he says.

Cohen went to a third physician. “I’m not God, or a prophet,” said that doctor, who enrolled Cohen in a clinical trial for an experimental form of chemo, which, Cohen says, is “prolonging my life.”

“He’s a very positive person — he sees everything as half-full,” says Charles Anteby, director of development at the Brooklyn-based Sephardic Bikur Holim, who’s known Cohen for two decades. Cohen volunteered for the organization shortly before his cancer diagnosis, and recently appeared at a SBH fund-raising event at a Deal home – he sang some of the songs he’s composed, and told his story.

“He’s a source of inspiration to many people,” Anteby says. “He appreciates little things – things we take for granted.”

Cohen and his wife are Orthodox Jews. “We always had strong faith,” Alexis says. Dealing with the cancer, she says, “just made it stronger. I feel closer to Hashem.”

With no cure for pancreatic cancer on the horizon, how long will the chemo continue?

“Till he’s 120,” says Alexis.

Which means more trips to Sloan-Kettering.

And more costumes.

steve@jewishweek.org