The evidence is clear that people with severe mental illness, such as schizophrenia and bipolar disorder, die earlier than the general US population.^1-3 Their lives are shortened by an estimated 10 to 30 years, and that mortality risk appears to be increasing.⁴ The leading causes of death are cardiovascular disease and cancer,⁵ which suggests that a better understanding of ways to provide preventive services to the population with severe mental illness could help to reduce the number of these premature deaths.

The article that accompanies this editorial by Iglay et al⁶ adds to the body of literature on breast cancer and early mortality in women with severe mental illness.⁷ The authors focus on mortality rates for women with preexisting severe mental illness who are 68 years of age or older (hereafter referred to as older women) and diagnosed with breast cancer. This age-group is important to study because older women have the highest incidence of breast cancer.⁸

The study not only evaluates a large nationwide data set of publicly insured women but also is the first, to our knowledge, to assess differences between women with and without severe mental illness with regard to specific characteristics of their breast cancer, including stage, tumor markers, tumor size, and lymph node involvement, by using the comprehensive SEER registry linked to Medicare enrollment records. This approach has allowed the authors to make comparisons of disease progression at the time of diagnosis between these patient populations.

One of the study’s most notable findings with major public health implications is that patients with severe mental illness were diagnosed with breast cancer at later stages. Compared to women without mental illness, a larger proportion of these women were diagnosed beyond stage I (46.4% v 40.2%), had a tumor size > 20 mm (37.6% v 30.3%), had poorly differentiated tumors (28.0% v 24.0%), and had one or more positive lymph nodes at the time of initial diagnosis (40.7% v 33.2%). These findings suggest that women with severe mental illness experience later presentation to care and delayed diagnosis.

Although much debate exists in the field with regard to screening mammography,^9-12 the current US Preventive Services Task Force guidelines recommend biennial screening mammography for women 50 to 74 years of age.⁸ The work by Iglay et al⁶ raises the question of whether women with severe mental illness are receiving adequate screening during their younger years. Recent evidence has indicated that publicly insured women with severe mental illness receive less breast cancer and cervical cancer screening than the general population.^13,14 This disparity is multifactorial but seems to be a problem with access and care coordination. People with severe mental illness use primary care less frequently than the general population,¹⁵ which often makes community mental health clinics their default medical home. Older women with severe mental illness most likely have been suffering from their psychiatric condition for decades and have accessed specialty mental health care services. Despite many encounters with mental health providers, however, they have fallen through the cracks of receiving preventive medical services.

The work of Iglay et al⁶ also offers a new perspective on research about cancer in the population with severe mental illness. Previous research on the association between schizophrenia and cancer incidence has produced contradictory findings,^16-18 which may reflect variation across demographic groups with severe mental illness and various types of cancer. Previous reports of lower rates of cancer among people with severe mental illness also have possibly reflected poor screening rather than lower rates of disease. Contrary to previous work,^19,20 the authors did not find a higher rate of breast cancer–specific mortality in older women with severe mental illness, which may be explained by the higher rate of all-cause mortality, with cardiovascular diseases most likely the result of the majority of premature deaths. Iglay et al⁶ report a 5-year cumulative incidence for all-cause mortality in people with severe mental illness of 38.0% (95% CI, 31.4% to 44.5%), which is nearly double that of people without mental illness (19.4%; 95% CI, 17.8% to 20.3%; P < .001). Although the all-cause mortality hazard ratio was highest for women with severe mental illness (2.19; 95% CI, 1.84 to 2.60), there was a statistically significant higher rate of all-cause mortality for women with depression (1.39; 95% CI, 1.22 to 1.58) and anxiety and depression (1.26; 95% CI, 1.03 to 1.53) than for women with no history of mental illness.

The causal mechanisms that underlie these findings need to be explored further. In the study population of Iglay et al,⁶ women with severe mental illness reported higher rates of tobacco use and comorbid conditions, had a lower median income level, and were less likely to be married—all risk factors for all-cause mortality.²¹ In addition, tobacco use may increase the risk of breast cancer,²² and low socioeconomic status is associated with later stage of breast cancer diagnosis.²³ To our knowledge, no data connect biopsychosocial pathways to differences in tumor biology among women with severe mental illness and those without, but despite a careful controlling for variables, confounders are tough to avoid, which is an ongoing challenge to a field that relies largely on retrospective cohort studies.

Although the contributory roles of poverty, stigma, ability to engage in treatment, medical decision making, and quality of care are difficult to disentangle in analyses of breast cancer diagnosis and survival, the approach by Iglay et al⁶ of linking claims data to geographically defined population-based patient registries such as SEER is a potent statistical method. That said, outstanding questions for more research include the following: To what degree does an increased inflammatory response contribute to breast cancer development in this population? What is the role of psychotropic medications in attenuating, exacerbating, and modulating breast cancer morbidity and mortality? With improved screening, what is the difference in breast cancer incidence in women with severe mental illness compared with the general population? How do treatment decisions differ for women with severe mental illness compared with those for other women?

On the clinical and policy level, Iglay et al⁶ sound the clarion call to fund and develop health care services that integrate primary preventive services within specialty mental health care settings. Although several health care delivery models have been proposed,^24-30 systematic reviews have failed to identify sufficient evidence and to recommend a specific model.^31-33 In addition, although National Institutes of Health–funded trials have examined satellite primary care clinics, disease self-management, electronic reminders, and clinical decision support programs, to our knowledge, none of these studies have examined models to improve breast cancer screening for these vulnerable women.

One solution may be to leverage registries to track whether women with severe mental illness are receiving guideline-recommended screening. A recent evaluation of a model that used registries to enhance cardiometabolic screening in a community mental health center found this approach to be effective and low cost.³⁴ That model consisted of four key components (patient-centered team, patient registry, screening protocols, and treatment protocols) and is a mirror image of the evidence-based collaborative care model that brings behavioral health to primary care clinics.³⁵ The patient registry allows for panel management because providers can track abnormal laboratory results or follow up with patients who are unable to receive screening tests. Although additional logistical challenges to providing breast cancer screening services exist, theoretically this same model could be used to ensure breast cancer screening of these vulnerable women.

We believe that preventive health care services should be delivered where women are already receiving care, especially for patients with severe mental illness who may have cognitive difficulties in accessing care, are marginally housed, and have low income. Mobile mammography administrators could partner with community mental health clinics to deliver care where the patient already is being seen.^36,37 Administrators can create incentives for coordinating care and reward providers who provide screenings to at-risk patients. Future mixed-methods studies should examine patient understanding of and preference for treatment along with quality and outcomes data that compare women with and without severe mental illness.

In summary, women with severe mental illness are diagnosed with more-advanced breast cancer than their counterparts in the general population. Evidence demonstrates that this population also faces more barriers to accessing preventive care and appropriate treatment. Thus, a critical need exists for an increased emphasis on guideline-recommended screening mammograms for this marginalized population. These reforms in health care are not technically difficult, but they do take time, resources, and an institutional commitment to improving overall medical care for people with severe mental illness. The findings of Iglay et al⁶ highlight the disparity in breast cancer care for people with severe mental illness and the need to integrate preventive care into community mental health clinics, or these women will be overlooked.