Researchers in Copenhagen looked at data on nearly 2 million Danish women between 1998 and 2011, all of whom were initially free of cancer. During the study period, they found nearly 45,000 women were diagnosed with breast cancer.
The risk of having to check into a hospital for severe depression was 70 percent higher for the breast cancer patients in the first year after diagnosis than their cancer-free peers. The breast cancer patients were also three times more likely to use antidepressants during the first year after diagnosis.
And that depression did not go away quickly, said lead researcher Dr. Christoffer Johansen, a professor of oncology at the Danish Cancer Society Research Center. The women diagnosed with breast cancer used antidepressants more than their peers up to eight years after their diagnosis, he found.
"Doctors treating these women must be attentive to this problem and try to address the issues leading to a depression as part of the clinical treatment of breast cancer," Johansen said.
The study was published online Oct. 27 in the Journal of Clinical Oncology.
Only an association was seen between breast cancer and depression, and the researchers did not examine why the women were depressed, but Johansen shared some theories.
"Cancer is feared, as it may metastasize, recur and even kill you," he said. "Many patients become overwhelmed when facing the diagnosis and treatment trajectory, and for some this exposure is so hard to cope with that they become depressed. In general, some 20 percent of cancer patients experience a clinical depression during the first five years as cancer survivors."
In the study, the researchers found that being aged 70 or older, having node-positive breast cancer (when the cancer has spread from the breast to the nearby lymph nodes) and having other serious health problems all increased the risk for depression the most. The type of surgery or treatment had no effect on depression risk, researchers found.
The study echoes others that have found an increased risk for depression in women with breast cancer.
The findings are not a surprise to social worker Matthew Loscalzo, executive director of supportive medicine at the City of Hope Cancer Center, in Duarte, Calif.
"When you have an illness like this, it's always in the back of your mind," he said. "It affects major life decisions."
Loscalzo said many women who have been treated for breast cancer take medicine such as aromatase inhibitors for several years after the treatment, to reduce recurrence risk. So that is a constant reminder of the cancer.
The finding that women past 70 were at greater risk of depression than younger Danish women was a bit surprising, Loscalzo said. "We find older people often cope better with life's challenges," he noted.
The changes that occur during cancer treatment and afterwards can also affect work, social and family life, he said.
Recently, guidelines adopted by the American Society for Clinical Oncology and others call for health care professionals to screen all cancer patients for depression and anxiety. That is a good standard, Loscalzo said.
That guideline is already in place at City of Hope, he noted. "We ask about quality of life," he said. Using a computer program, patients complete a brief touch-screen survey, which tells the health care professionals much about their state of mind, including any anxiety or depression, he said.
Women with breast cancer should not wait until their doctor asks them about depression and anxiety, if they are experiencing it, Loscalzo said. "Ask for a referral [to mental health services]."
"Breast cancer is one of the cancers in which we have the best opportunities for treatments," Johansen said. "Women who are diagnosed with this cancer in general can expect decades of life following the primary treatment, and part of that life as a survivor [includes] care taking of the mental health."
To learn more about depression and cancer, see American Society for Clinical Oncology.