Dealing with two types of cancer, Linda Moore felt happy to live in Houston, home to one of the country’s top hospitals. Then came a letter from her insurance company earlier this year.

“I was quite sure I must not be reading it correctly,” she said. But she was: Blue Cross and Blue Shield of Texas was indeed discontinuing her Preferred Provider Organization plan, meaning that continuing treatment at MD Anderson Cancer Center is about to become alarmingly expensive.

PPO plans give patients flexibility to choose almost any doctor or hospital without risking major financial penalties for going out-of-network. But they are an endangered species on the Affordable Care Act’s 2016 exchanges.

There are no PPOs being offered via the federal marketplace in 2016 in Houston, the country’s fourth-largest city, or in New Jersey and New York. An analysis of silver-level Obamacare PPO plans by the Robert Wood Johnson Foundation noted that only a third of this year’s offerings will stay the same in 2016, with many carriers exiting the market, dropping their plans or reducing their availability.

UnitedHealth, the country’s largest health insurer, said on Thursday that it is considering leaving the exchanges in 2017 because of what its CEO described as unsustainable losses.

“I think the carriers have lost money on the exchanges in general but lost money in particular with PPOs and I think the thing that’s been the biggest problem for them is allowing people to have access to out-of-network providers,” said Kathy Hempstead, director of coverage issues at the Foundation.

The bigger the city, of course, the more providers there are. And Hempstead theorized that when the Affordable Care Act was introduced, companies were under pressure to grab a big share of the market so offered attractive plans that have proved unprofitable.

“Since the Affordable Care Act began, the market has changed. We found that the individual PPO plan was no longer sustainable at the cost it was being offered. Because we want to make sure that our plans are affordable, we decided to not offer individual PPO plans in 2016,” Blue Cross and Blue Shield of Texas said on its website.

The company says it has case management programs to help with the transition to Health Maintenance Organization plans. These typically do not cover out-of-network visits and require non-emergency care to be coordinated through a primary care physician.

“For a lot of people it’s not going to matter that much,” said Hempstead, adding that most customers care more about price than choice. However, she said: “For some people it’s going to be a problem.”

For many, changing plans will bring little more than inconvenience and perhaps an obligation to find a new doctor. But for families with complex needs, the loss of a PPO presents an agonising choice: risk financial hardship or settle for potentially inferior care.

Moore was diagnosed with breast cancer in 2008 and underwent a double mastectomy. Earlier this year she discovered she had thyroid cancer and had half her thyroid removed. She requires regular check-ups and wants to continue going to MD Anderson, but the replacement plan she has found with a local healthcare system, her sole PPO option, would cover only 50% of the costs. “It will add up quickly,” she said.

Moore’s form of breast cancer, triple negative, is hard to treat if it recurs. She would feel more confident about the quality of her care at MD Anderson, the nation’s top-ranked cancer hospital according to US News & World Report. “They are going to be the ones who are most likely to know of some innovative thing,” she said.

Moore and her husband, Ricky, together pay $1,500 a month for their soon-defunct plan, which will rise to $1,600 for the new, more restrictive, scheme. Photograph: Linda Moore

Moore and her husband, Ricky, together pay $1,500 a month for their soon-defunct plan, which will rise to $1,600 for the new, more restrictive, scheme. It will be about $400 a month to cover their daughter, Sarah, who goes to MD Anderson because she has atypical moles, a risk factor for melanoma.

Linda Moore, 56, gave up her job as a teacher to care for Sarah, who has a string of serious health problems and is aged 25 but functions like an 18-month old. In 2012, Ricky had to quit his career as a construction manager when he developed a blood clot. That meant the 54-year-old lost his health insurance and the family had to turn to the federal exchange.

The family are clients of Jason Bohmann, a broker with Texas Health Design. He said he receives three or four calls a day from people wondering how to handle the loss of their PPO. “There’s a lot of fear out there,” he said, adding that the price of HMOs is rising.

“In 2016 you’re going to pay exactly the same for an inferior network that may have 40% or 30% of the doctors you had last year,” he said. “More inconvenience, less choice, all for the same money. Doesn’t sound like a good deal.”

For Linda Moore, one of the jewels of the largest medical complex in the world is suddenly so near yet so far.

“[I was] needing the innovation of MD Anderson, always being grateful that I happen to live in the town where MD Anderson is, and now like so many people who live in the town I’m not going to be able to go to the place unless I really want to dip into my savings, cash out my 401(k), that kind of thing,” she said. “I could always go to an in-network oncologist and maybe things will go well; I don’t know.”

Instinctively risk-averse, for the first time in her life she is considering going without coverage to avoid having to dip into her retirement savings to cover regular healthcare costs. In other words, gambling that she will not fall seriously ill again.

“Just don’t go the doctor. Don’t do those preventative care visits that probably helped me find out I had breast cancer and thyroid cancer early on. Just don’t find out and don’t get it fixed,” she said. “Which is ludicrous but at this point what do you do? It becomes insanely expensive, it’s a whole different ball game from what it used to be.”