Surviving cancer can bring on another ailment — post-traumatic stress disorder. A recent study found that about one-fifth of patients had PTSD several months after their cancer diagnosis.

Many of those patients lived with PTSD for many years, the researchers noted. The findings by Malaysian researchers were published in an American Cancer Society journal.

The 469 study participants had various kinds of cancer, and they were tracked for four years. The PTSD rate was more than 21 percent six months after their diagnoses. That figure dropped to 6.1 percent after four years.

PTSD can affect people who have been through a life-threatening event. It can cause disturbing memories of the experience, as well as anxiety and flashbacks.

While the PTSD rate fell over time, about one-third of patients who had an initial PTSD diagnosis were still having persistent or worsening symptoms after four years. Researchers said the tough mental attitude that many patients develop to fight their disease may discourage them from acknowledging the possibility of PTSD or getting help for it.

Lingering PTSD may also have its roots in a fear of cancer recurrence, the study showed.

Cancer patients’ mental well-being needs to be assessed along with their medical treatment, researchers said. The value of mental-health care is evident: Breast cancer survivors in the study were almost four times less likely to develop PTSD than patients with other cancers, perhaps due to a dedicated support and counseling program.

If you or a loved one have cancer or have survived it, consider the potential benefits of a psychological evaluation. It isn’t just your body that has undergone a trauma.