THE FIRST TIME I SAW KRIS KONO in a DJ booth, it was Valentine’s Day 2009. She was spinning for a big crowd of girls at Machine and had a huge smile, even as she fretted over equipment problems. I’d known her for only a week, and she’d called earlier that day to invite me to the club. She was putting my name on the list, in case I wanted to come and bring a friend.

My pal Michael and I skipped the line and headed downstairs to the thumping music and pulsing lights. During a break, they were auctioning off a date with Kris. I asked Michael if he had any money. A hundred bucks later, she was mine. It was a ridiculous bargain for the hottest DJ in Boston, as Kris would often remind me.

After the date (dinner and a dog walk at the Arboretum), Kris sent purple and white orchids to my office and a YouTube link to Billy Fury singing “I Think You’re Swell.” She was hilarious, tall, and beautiful. She kept rows of Matchbox cars on the shelves in her kitchen and a disco ball sparkling from the ceiling fan, and she had cool Buddha statues everywhere. She liked loud, upbeat music, eating Greek cherry jam from the jar, and playing fart apps on her iPhone for my nephews. Her only flaw seemed to be the Derek Jeter doll perched by her TV set. But her Dad had been a big Yankees fan, so she came by it honestly.

When Kris started having mild stomachaches that summer, she was pretty low-key about it. She switched from dairy to soy. She kept a food journal, and we tried going vegetarian. After a while she saw a doctor. The X-rays showed a small mass pressing on her right ureter. They did a biopsy. We figured it was all precautionary.

But it was more complicated than that. On March 9, 2010, Kris had surgery at Beth Israel Deaconess Medical Center to remove the mass. Late that night, I was standing by her bed in the recovery room when one of the surgeons came by. He told me about all the stuff they took out — the ureter, a fibroid, and some other suspicious things — then said: “It is cancer. So you’re going to want to see an oncologist.’’

I heard myself say “It’s cancer?” He nodded and talked some more. He didn’t seem alarmed. I looked down at Kris sleeping peacefully.

After an unhelpful follow-up visit with the other surgeon, we started reaching out to everyone we knew with some oncology expertise and got an appointment at Dana-Farber, the famous cancer hospital in Boston. But the problem was, we didn’t know what kind of cancer Kris had.

The analysis of the mass by Beth Israel suggested it could have started in the pancreas or the upper gastrointestinal tract. There was a chance, though slimmer, it started in either the urinary or gynecologic tract. The test seemed to rule out the colon. The diagnosis was vague and troubling at once: “Adenocarcinoma of unknown primary.”

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ABOUT 200,000 PEOPLE a year learn they have cancer when a metastasis shows up — a tumor that’s spread from disease elsewhere in the body. Doctors can often figure out pretty quickly where the cancer started — most commonly the lung, breast, colon, or prostate — and the treatment is targeted to that particular form of the disease. But for around 60,000 of those folks, the doctors can’t pinpoint the cancer’s origin in any of the usual ways, making it difficult, if not impossible, to treat. That’s cancer of unknown primary, or CUP.

When Kris got sick, there was very little on the Internet about CUP. But every study that turned up seemed to have the same name on it: J. Scott Nystrom. A doctor in the oncology department of Tufts Medical Center, Nystrom has been studying this mystery disease for more than 30 years.

“One of the difficulties in treating CUP patients is that their presentation is atypical,’’ says Nystrom, 68. If a doctor suspects breast cancer but the mammogram comes back negative, it’s hard to get past that. “To treat a patient absent that knowledge is very difficult for oncologists to accept,’’ he says.

Nystrom looked at Kris’s reports, examined her, and said, “I bet they gave you all kinds of tests and didn’t find anything, right?” He was exactly right. Everything had come up negative. Nystrom sent Kris’s tissue samples to a California lab for gene-based testing, to determine the probability that the cancer started in one of 15 sites. At least half the time, the findings result in a change of diagnosis and treatment, Nystrom said. He’s tested male patients — at least one a smoker being treated for lung cancer — and discovered they actually had breast cancer.