Impact of Preexisting Mental Illness on All-Cause and Breast Cancer-Specific Mortality in Elderly Patients with Breast Cancer

Authors: Iglay K., Santorelli M., et. al.

Source: J Clin Oncol 35:4012-4018

ascopubs.org/doi/abs/10.1200/JCO.2017.73.4947

Patients with mental illness have higher mortality rates compared to the general population. These individuals suffer more often from chronic illness, including cancer. The investigators in this study examined associations between mental illness and breast cancer-specific mortality.

Over 19,000 women who were at least 68 years old were included in the study. According to nationally collected data, they were diagnosed with stages I, II or IIIA breast cancer. Records were then reviewed for diagnoses of mental illness. Almost 3% of women had severe mental illness (schizophrenia, bipolar or other psychotic disorder). Almost 8% had a diagnosis of depression, 6% had anxiety and almost 4% had anxiety and depression.

Women with severe mental illness had an overall mortality rate of 38% compared to a rate of 19.4% among women without mental illness. Severe mental illness was associated with a breast cancer-specific mortality rate of 7.2% compared to a rate of 6.7% among women without mental illness. Women with mental illness were more often diagnosed with breast cancer beyond stage I. They more often presented with tumors larger than 2cm and with positive lymph nodes. These women also more often had more aggressive disease. There were many observations that helped to explain these discrepancies.

Women with severe mental illness had a greater rate of tobacco use as well as multiple coexisting diseases. These factors may have increased their risk of developing breast cancer. Some medications prescribed to treat mental illness have been shown to increase the growth of breast tissue and possibly increase breast cancer risk. Women with severe mental illness tended to have lower income, and fewer of them were married. Moreover, these women may have experienced a well-known phenomenon called diagnostic overshadowing, where a patient’s symptoms of disease are mistakenly attributed to her mental illness. Finally, the women with severe mental illness may not have understood the importance of screening mammograms, their diagnosis, treatment recommendations or the reasons for initiating or continuing treatment.

The investigators concluded that the observed differences in breast cancer outcomes among women with mental illness may be reduced or eliminated with more attention to the individual needs of these women. Awareness, close guidance and follow up by a woman’s team of providers can provide her with the support, care and reinforcement that could improve overall and breast cancer-specific mortality.