Financial benefits do not explain survival improvement among married patients with cancer

Unmarried patients with cancer had a greater risk for mortality than married patients, according to an analysis of data from the California Cancer Registry.

However, the distinct survival advantage for married patients did not appear to be caused by socioeconomic resources or health insurance status.

“While other studies have found similar protective effects associated with being married, ours is the first in a large population-based setting to assess the extent to which economic resources explain those protective effects,” Scarlett Lin Gomez, PhD, research scientist at the Cancer Prevention Institute of California, said in a press release. “Our study provides evidence for social support as a key driver [and] research is needed to understand the specific reasons behind these associations so that future unmarried patients can receive interventions to increase their chances of survival.”

Improved cancer survival previously demonstrated for married patients may be explained through two pathways — social and material.

Because the impact of economic resources on the marriage-associated survival differences has not been well studied, Gomez and colleagues sought to analyze the difference in outcome based on health insurance status and neighborhood socioeconomic status (SES) between married and unmarried patients with cancer.

Researchers used the California Cancer Registry to evaluate a cohort of 783,167 patients with one of the ten most common sites of cancer and aged at least 18 years at the time of diagnosis from 2000 to 2009. They analyzed males (n = 393,470; 70% married) and females (n = 389,697; 51% married) separately due to the notable difference in HR for unmarried men and women.

After 1,801,907 person-years of follow-up for men and 1,903,874 person-years of follow-up for women, there were 204,007 deaths among men and 182,600 deaths among women.

Researchers found unmarried patients — which included those who were separated, divorced, widowed and never married — were more likely to live in lower SES neighborhoods, to be uninsured or have public insurance, to be diagnosed at a later stage of disease, and to not receive surgery or radiation. Further, more unmarried patients were black and comprised the oldest and youngest age groups.

Ninety-eight percent of patients had health insurance, the most common of which was private insurance. Uninsured males (HR = 1.23; 95% CI, 1.2-1.27) and females (HR = 1.24; 95% CI, 1.19-1.28) had an increased risk for death from all causes than privately insured patients.

All-cause mortality rates were higher for unmarried men (HR = 1.27; 95% CI, 1.26-1.29) and women (HR = 1.19; 95% CI, 1.18-1.2).

HRs did not vary significantly among never married, widowed, divorced or separated women. However, never-married males demonstrated a higher HR than all other unmarried subtypes (HR = 1.26; 95% CI, 1.24-1.26).

After adjusting for insurance status and neighborhood SES, the association between being unmarried and increased risk for all-cause mortality persisted, although to a lesser degree, among men (HR = 1.22; 95% CI, 1.21-1.24) and women (HR = 1.15; 95% CI, 1.14-1.16).

Unmarried patients who were underinsured and living in higher SES neighborhoods had higher risks for mortality (men, P = 6.8 x 10^–9; women, P = 8.2 x 10^–8).

“[These] findings may be related to the higher out-of-pocket costs for uninsured individuals, with those financial challenges compounded by the higher costs of living in higher SES neighborhoods,” the researchers wrote.

Although these results suggest economic resources do not explain the survival benefit among married patients, previous evidence suggests that higher levels of social support may mitigate the harmful physiological effects of stress and inhibit tumor progression through immunologic or neuroendocrine pathways, according to the researchers.

Other specific advantages for married patients with cancer include better adherence to treatment, screening and healthier behaviors.

“Our results suggest that, because economic resources likely play a minimal role in explaining the detrimental survival experienced among unmarried cancer patients, future research that focus on social support and other socially mediated factors associated with marriage may provide an important avenue to inform interventions that improve cancer survival,” Gomez and colleagues wrote. – by Nick Andrews

Disclosure: Gomez and one other researcher report grants from Genentech outside of this analysis.