That phrase is often code for internal corporate strife, personnel clashes, or failure to perform. But in Shaw’s case, the explanation was as personal and familial as it gets: Her older sister, Sherry, 51, was suffering from multiple myeloma, or bone marrow cancer. Though Sherry’s condition had deteriorated since her 2013 diagnosis, in early April she had been accepted into a promising clinical study. A key criterion for admission was that she have a full-time caretaker during the three-month trial.

For Shaw, 49, one of the top-ranking women in the pharma industry, the decision to take on that caretaker role was an easy one. She deliberated just two days before submitting her resignation. What surprised her was the disbelief she encountered from friends, co-workers, and colleagues in the industry.

“A lot of recruiters call. They think the official story they have heard isn’t true,” says Shaw, who worked at Novartis (NVS) for six years. “I had a one-on-one with the CEO, and he said, ‘I am amazed by your courage.’ I said, ‘What do you mean?’ And he said, ‘You are walking away and don’t know where you will go after that.’”

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As a woman embracing the responsibility of caring for a loved one, Shaw is not alone. Two-thirds of caregivers in the U.S. are female, according to industry group Caregiver.org, which reports that the average caregiver is a 49-year-old women helping her 60-year old mother. A 2014 survey of 25,000 Harvard Business School grads ages 31 to 67, showed that 28% of Gen X women and 44% of Baby Boomers had taken a break of more than six months to care for children. Only 2% of men in both age groups had done the same.

To be sure, Shaw has advantages many caretakers do not. Financially, she is in a position where she can afford a long break. With 27 years in the pharma industry, she can also draw on deep connections in the medical community that most people cannot dream of. Her family is tight-knit and supportive, and a second sister, Shelley, 42, is also stepping away from work to help out.

Nevertheless, Shaw faces many of the same choices and challenges as her peers: What will be cost of “pausing” her career? How long can she afford to not work? What will she do afterward? What will her state of mind be during this trying period?

When Sherry, a mother of two from St. Louis, was first diagnosed, Shaw tried to juggle her career and her sister’s care. As Sherry went through a bone marrow transplant and multiple other treatments, Shaw was by her side in the hospital, but always on email and phone calls. As Sherry got sicker, she increasing relied on Shaw. And when it became clear that Sherry had a chance to get into the clinical trial, Shaw went to her Human Resources department. “I said, ‘If my sister gets in, I have to be with her.’ She gave me this horror look and was like, ‘We don’t have anyone to replace you.’”

Shaw’s husband, too, was concerned about his wife’s plan to step down, in part because she is the main breadwinner in the family, but also because he thought she would be bored and without a purpose.

Though the HR representative suggested a leave of absence, Shaw felt uncomfortable with that option, since she was unsure how long she would be away from the job. What’s more, she didn’t see herself moving to Basel, Switzerland, where Novartis is headquartered, which would have been the next logical step in her career at the company.

“Am I taking myself off the career track? Have I leveraged the skills I have to become a CEO? That’s still a question. But I have to say, I’m okay if I derail myself,” says Shaw.

It seems that Shaw’s career developed so she could take care of Sherry now. Growing up on an Iowa farm, she became interested in business through her dad and learned about caring and giving from her mom. Even before college, knew she wanted to combine these two sides of herself by working in the pharmaceutical industry. By the time Shaw joined Novartis in 2010 as head of oncology for North America, she had almost two decades in the field. She was promoted to president in 2014, and among other things, worked to create empathy for patients who rely on Novartis products. In simulation exercises, company executives experienced what it’s like to be a heart failure patient by breathing through straws, walking with weights in their shoes, checking into a mock-hospital, and upon “discharge,” having to choose between paying for follow-up medications and groceries.

In 2012, before Sherry got sick, Shaw heard about an experimental cancer therapy program called CAR-T, underway at the University of Pennsylvania. The protocol, designed for leukemia patients, had caught the attention of some Novartis executives. It was a personalized approach to treatment, in which doctors removed some of a patient’s blood, separated out the T-cells, genetically modified those cells, then re-injected them into the patient. Novartis soon purchased the technology and partnered with Penn to pursue the trials.

By the time Sherry’s bone marrow cancer relapsed in late 2015, the CAR-T trials had been expanded as a possible treatment for that disease as well. Shaw arranged for Sherry to be assessed and says she remembers thinking, “They probably don’t want to see the president of Novartis.” She knew the odds were slim, since only four others had met the qualifications to participate. But on a Friday in early April, Sherry was accepted. On Monday, Shaw called the head of HR in Switzerland and submitted her resignation.

A Novartis spokesperson tells Fortune,“The company thanks Ms. Shaw for her dedication, passion and commitment as well as her inspirational leadership, resulting in one of the most successful launches in the industry to date with the introduction of Cosentyx.”

Shaw says she has not reconsidered the decision. She has seen the difference an effective advocate can make in the life of a patient. In 1996, Shaw lost her mother to breast cancer. In 2009, her father was misdiagnosed four times before he died of a rare infection. Shaw says the most important question she asked was, “What’s the choice you’ll wish you had made at the end of your life? In corporate America, you are so replaceable. The minute you walk out the door, there is someone to step in for you. Everyone says it. Do you wish you sent more time with your family, or at work?”

Shaw left Novartis May 1 and Sherry is scheduled to start treatment today, May 31, barring any development that could disqualify her at the last minute. In the first few weeks away from the company, Shaw has worked on starting a foundation, More Moments More Memories, to aid families in positions similar to her own, but without the financial resources to take time off of work or to travel and stay in another city for a clinical trial. Hopefully, the helping hand will translate to extra time for families with their loved ones, says Shaw: “These are moments you get that you will have for the rest of your life.”