A cancer diagnosis is typically accompanied by heavy emotions. When someone goes through cancer testing and treatment, it's normal to feel fear, stress, sadness and worry.

Sometimes these feelings severely affect the quality of life. When this happens, post-traumatic stress disorder (PTSD) may be to blame.

Below, Craig Sawchuk, Ph.D., L.P., co-chair of Mayo Clinic's Division of Integrated Behavioral Health, answers some frequently asked questions about cancer-related PTSD.

Q: How common is cancer-related PTSD?

A: Research tells us that about 4% of people with recently diagnosed, early-stage cancer may experience PTSD. For people whose cancer returns after remission, the rates may go up to 35%. People with breast cancer seem to have slightly lower rates, while those with brain, gynecologic, ovarian and blood cancers may have slightly higher rates.

Q: How is cancer-related PTSD different from being afraid or worried about your diagnosis?

A: PTSD occurs when the intensity of the symptoms start to cause problems in your day-to-day living. It typically affects multiple aspects of life — home life, personal life, work life and social life.

With PTSD, intense memories or images associated with cancer can be hard to shake. People with cancer-related PTSD may avoid reminders of cancer so much that it interferes with daily life. For example, they may avoid leaving home because they don't want others asking about cancer.

They might also feel jumpy, on edge or physically "wired." They may have difficulty sleeping or snap at loved ones.

Q: Are certain people more susceptible to cancer-related PTSD?

A: Cancer-related PTSD can affect people who have cancer and the parents or caregivers of those people. It can occur at any time during the cancer experience, including after treatment.

If you've had a history of trauma or PTSD, you're more likely to experience cancer-related PTSD symptoms. A cancer diagnosis — and the feelings of helplessness and loss of control that can accompany it — can reactivate these feelings.

The invasiveness of cancer treatment can also affect PTSD rates. People who've had ICU stays or medical procedures associated with physical trauma, pain or feelings of helplessness are at higher risk.

Q: What aspects of the cancer experience might cause PTSD?

A: Traumatic stress occurs when an event is extreme and beyond the norm. In the cancer experience, there are many elements that can lead to this kind of trauma.

When you undergo cancer testing, the waiting and not knowing can trigger these feelings, especially if the diagnosis has the potential to limit your life expectancy. Receiving a diagnosis can be traumatic — the word "cancer" holds a lot of power.

The nature of treatment, from chemotherapy to invasive surgical procedures, can be especially distressing. And the way treatment disrupts your life — upsetting routines and family or work roles — can be traumatic.

Loneliness, lack of social support, financial strains, pain and loss of function can all cause significant stress. Even when treatment is successful, follow-up testing and the fear of recurrence can continue to contribute to that stress.

Q: What are the warning signs of cancer-related PTSD?

A: After a cancer diagnosis, it's not uncommon to have temporary anxiety or depression, sleeping problems, nightmares, or an inability to function like you did before cancer.

It's when those symptoms affect your day-to-day rhythms for a month or longer that it's time to take a closer look. That's a sign that something needs to be addressed.

Symptoms may include:

• Flashbacks and nightmares. You might replay the moment you learned of your diagnosis, particularly difficult treatments or other stressful experiences.
• Avoidance of cancer triggers or reminders. People with cancer-related PTSD may avoid necessary treatments, testing or follow-up appointments.
• Changes in thinking and mood. Difficulty concentrating, along with intense fear, guilt or anger, can be signs of PTSD. Alternately, you may feel numb, "flat" or emotionless.
• Trouble sleeping. Disrupted sleep is a common symptom.
• Arousal symptoms. People with PTSD startle easily, and tend to be hyper vigilant in other areas of their day-to-day lives.

Some of these symptoms may be side effects of certain cancer treatments. Your health care team can help you sort out causes and next steps.

Q: What should you do if you think you have cancer-related PTSD?

A: If you're experiencing one or more of the above symptoms for at least one month, reach out and have an open conversation with your health care provider. The sooner you address your symptoms, the sooner you can start feeling better. Early treatment is important.

Q: How is cancer-related PTSD managed?

A: There are several ways to treat cancer-related PTSD.

Natural antidepressants — like getting enough sleep, eating a healthy diet, exercising, maintaining social support and engaging in meaningful activities — are key to improving mental health. Taking time for yourself allows healing to occur.

Counseling can also be helpful. Talking with a therapist can help address the trauma and help you process your cancer experience. He or she can also help you learn stress management techniques, which can improve quality of life and PTSD symptoms.

A therapist can also recommend a carefully moderated support group. Support groups that are not carefully moderated by a mental health professional can be harmful if one or more group members dominate the discussions with traumatic content.

There may also be medication options. Some people find antidepressants helpful for managing any anxiety or depressive symptoms that can accompany PTSD. Your health care provider may also be able to recommend medications to help with nightmares.

Q: Is it really possible to feel good again?

A: I would never wish a traumatic experience on anyone. But I've seen it be a real turning point for many — and ultimately get people to a better place in life.

The truth is that sometimes traumatic things happen to good people for no reason. But when you tap into your inner resiliency — that part of you that helps you bounce back from the traumas and stresses that life throws at you — you can deal with those difficult experiences in a more positive way.

I've seen people use their traumatic experiences in ways that make them grow. They may reach out to help others deal with cancer, create deeper relationships, grow spiritually, or take action in really positive and hopeful ways. You can, too.