Being diagnosed with cancer can be overwhelming mentally, physically, and emotionally. Experiencing moments of anxiety, sadness, or fear is a normal part of a patient's cancer journey, but what about prolonged feelings of hopelessness, worthlessness, and thoughts of suicide?

These more serious symptoms are all signs of depression, says Dr. Scott Irwin, psychiatrist and director of Supportive Care Services at Cedars-Sinai's Samuel Oschin Comprehensive Cancer Institute.

"In the general population, about 7% of adults will experience an episode of major clinical depression," says Dr. Irwin. "That number increases to 15-25% for people with cancer."

Symtoms of clinical depression include:

• Depressed mood, ongoing sadness
• Loss of interest or pleasure in usual activities
• Lowered energy or fatigue
• Change in weight or appetite
• Being agitated
• Increased or decreased sleep
• Feeling guilty, worthless, hopeless, or helpless
• Difficulty with concentration or indecisiveness
• Frequent thoughts of death or suicide

Many of these symptoms can overlap with the side effects some patients experience from cancer treatment, such as lowered energy, decreased appetite, weight changes, insomnia, and impaired concentration.

So how do you know? A good rule of thumb: If 5 or more of the symptoms of clinical depression listed above occur nearly every day for 2 weeks or more, it might be depression rather than side effects of treatment.

Dr. Irwin says the nonphysical symptoms are his key to spotting a cancer patient struggling with clinical depression.

"When I'm assessing a patient, I focus on the nonphysical symptoms more," he says. "Feeling depressed, down, blue, or sad, an inability to experience joy, excessive guilt, and thoughts of actively ending one's own life are all signs that someone is dealing with clinical depression."

If you or a loved one are experiencing any of these symptoms, it's important to discuss what you're feeling with your oncology care team and ask about mental health services.

At Cedars-Sinai, services within the cancer institute include access to mental health experts—such as social workers and psychiatrists—with specialized expertise and training to care for patients and families dealing with cancer.

"It's important that mental health is assessed so we can intervene, treat, and relieve the suffering associated with it," says Dr. Irwin. "In cancer, this is even more important because doing so will improve cancer care outcomes."

If you or someone you know is considering suicide or self-harm, there are resources available to provide free and confidential support. Call the National Suicide Prevention Lifeline at 1-800-273-TALK or Teen Line at 1-800-TLC-TEEN.