Cancer gave Catherine, Princess of Wales, a 'new perspective on everything.' The mental health impact of the disease is profound, psychologists say.

Catherine, Princess of Wales, has completed chemotherapy treatment. In a video released Monday, the 42-year-old described the past nine months as “incredibly tough” for her and her family, sharing that the “path to healing and full recovery is long and I must continue to take each day as it comes.” The challenges, however scary, have also given the royal a “renewed sense of hope and appreciation of life.”

“The cancer journey is complex, scary and unpredictable for everyone, especially those closest to you. With humility, it also brings you face to face with your own vulnerabilities in a way you have never considered before, and with that, a new perspective on everything,” she said.

She’s not alone — in either the fear or the newfound sense of gratitude she discovered in the process of coping with cancer, according to psychologists. We spoke to two experts about the profound mental health impact cancer can have on patients and those closest to them.

Getting a cancer diagnosis can be overwhelming

The first step in the cancer journey — getting diagnosed — can be among the most jarring, experts say. “For many people, having a cancer diagnosis or even a potential cancer diagnosis is their worst fear,” Jessy Levin, a psychologist with Memorial Sloan Kettering Cancer Center, tells Yahoo Life. “The very beginning is overwhelming and a lot of people describe the period as having tunnel vision or tunnel hearing; it’s hard to focus on anything else.”

That overwhelm can ripple out to a person’s family and other loved ones. But these “support people” have a critically important job during this phase of the cancer journey, says Levin. “They feel a responsibility of being the keepers of information because they may be more able to focus on the technical aspects” of someone’s diagnosis and treatment plan than the person who has just found out they have cancer, she explains. Levin suggests people with cancer and their families make sure to have conversations about what questions they want to ask doctors and write them down before appointments, and take lots of notes during visits. This can help provide some comfort, clarity and a path through this time of tunnel vision when there is “such a rush of feelings,” Levin says.

Cancer is a difficult — but not uncommon — family affair

Tens of millions of people are diagnosed with cancer each year, per the World Health Organization. And that means that many families are affected by the disease. In fact, one 2017 CBS poll found that more than half of Americans had at least one immediate family member who had been diagnosed with cancer. Parents, in particular, who have received a cancer diagnosis may feel an impulse to close off to protect their children and other loved ones. But experts say it’s better to lean in. “We advise parents to try to be as open and honest with their children about what they’re going through, without giving too much unnecessary information,” Neha Goyal, a University of California, San Francisco psychologist who cares for patients with cancer, tells Yahoo Life.

Maintaining communication benefits both the person with cancer and their loved ones. “It’s really important to maintain connections to things [and people] that are meaningful to them, including family,” says Levin. She advocates for open communication because “one of the things that’s really difficult for people who are going through a cancer process is feeling really isolated and like people don’t understand that experience.”

Cancer can also put some relationships to the test. Sometimes a patient will expect a loved one to be a pillar of support and find they turn out not to be, while the opposite can be true as well, with someone unexpectedly being by their side. “Lean into being OK with asking for help ... but [while] recognizing that not everyone is able to provide the help they need,” Goyal advises.

How cancer shifts perspectives

The Princess of Wales frankly shared about her “new perspective” after undergoing cancer treatment, and experts say that shift is a common one for patients. A cancer diagnosis can “shatter the illusion of their immortality” for many people, says Goyal. “That forces them to sometimes figure out what is most important to them, and how they want to be spending the limited time they have as a human on this Earth, that’s why for many people it can create a new perspective,” she explains.

Life after cancer often isn’t the same as it was before — in ways both good and bad. “Part of that is living with having had cancer,” says Levin. “That doesn’t go away just because treatment has stopped.” Many patients have been through surgery that, in some cases, involves removing parts of their bodies. Fear of recurrence, fatigue, body image concerns, not getting exercise and sexual function issues are all common problems faced by cancer survivors, according to a 2017 survey.

A cancer diagnosis brings uncertainty, but “for some people that uncertainty becomes more profound or salient post-treatment,” says Goyal. “Once they’re done with treatment, people want to know ‘What just happened, what do I do now to make sure this doesn’t happen again?’ — and there’s no magic that will tell you what that answer is.”

What it means for life after cancer — and what we can all learn from survivors

For the princess, finishing treatment brought hope and gratitude but, as she acknowledged, the healing process isn’t over. “Grief can be a prominent emotion that comes up,” says Goyal. “There can be growth for people who have cancer, but there can also be loss: a loss of their sense of what their life is going to look like moving forward.”

Some simple life accounting can help cancer patients — and anyone — step into the future with newfound clarity and appreciation. Goyal recommends, regardless of whether you have cancer or not, taking an annual inventory of how you’re spending your time and what’s important to you. She advises asking yourself, “How much are those aligned or mismatched, and what can I be doing to align them better if they are mismatched?”