People who have been diagnosed with cancer are at greater risk of being hospitalized with depression, new research from Denmark shows.

While the risk was greatest in the year following a person’s diagnosis, the likelihood of being hospitalized for depression among survivors of certain types of cancer remained high for several years, Dr. Susanne O. Dalton of the Danish Cancer Society in Copenhagen and her colleagues found.

There’s some evidence that cancer patients are more likely to be depressed than people in the general population, the researchers note. Estimates of depression prevalence among these patients range from 0 percent to 38 percent.

Despite this variability, which is likely due to differences in how depression is diagnosed and the type of cancer patients have, as well as how advanced their disease is and whether or not they are hospitalized, “depression has typically been underdiagnosed and undertreated in the oncology setting,” Dalton and her team write in the Journal of Clinical Oncology.

To better understand the short- and long-term depression risk of cancer patients, the researchers looked at 608,591 Danish men and women who were diagnosed with cancer and were followed for up to 31 years. The average follow-up after diagnosis was 4.2 years.

Within the first year of being diagnosed with cancer, the researchers found, men and women with cancer were about twice as likely to be hospitalized for depression as were men and women in the general population. Over the next decade, the relative risk of hospitalization for depression was increased 21 percent for men and 5 percent for women.

Depression risk varied by cancer type. For both sexes, the risk remained high for up to 10 years after being diagnosed with a hormone-related cancer, such as breast cancer or prostate cancer. The risk also stayed high for a decade among women with smoking-related cancers and men with virus- and immune-related cancers.

In the first year after diagnosis, increased risk ranged from 1.16-fold for women with colorectal cancer to 3.08-fold for men with brain cancer.

Given that more and more people are living longer after being diagnosed with cancer, the researchers note, taking care of cancer survivors with depression will be increasingly important. “Early recognition and effective treatment of depression, both in the cancer setting and beyond, would have the potential to prevent admission for depression and thus reduce patient suffering and enhance the quality of life for cancer survivors,” they conclude.

SOURCE: Journal of Clinical Oncology, online February 17, 2009.