Association of social isolation and loneliness with incident cancer in A Population-based cohort study.

Background: Social isolation and loneliness pose significant public health challenges globally. This study aims to examine the association of social isolation, loneliness and their combined effects with incident cancer.

Methods: This study utilized data from the UK Biobank (UKB), which is a population-based prospective cohort. Social isolation and loneliness were assessed through self-reported questionnaires. Cancer cases were identified by linking to cancer registries.

Results: A total of 430,376 participants were included, during a mean follow-up of 14.32 years, 45,131 participants were diagnosed with cancer. Compared to participants in least isolated group, those in most isolated group had significantly higher risks of cancer of lip, oral cavity and pharynx (HR 1.32, 95% CI 1.11-1.58), cancer of digestive organs (HR 1.10, 95% CI 1.03-1.16), cancer of respiratory and intrathoracic organs (HR 1.17, 95% CI 1.07-1.28), breast cancer (HR 1.11, 95% CI 1.04-1.18), cancer of female genital organs (HR 1.23, 95% CI 1.09-1.38), and cancer of urinary tract (HR 1.31, 95% CI 1.17-1.46). However, the most isolated group had lower risks of cancer of mesothelial and soft tissue (HR 0.80, 95% CI 0.64-0.99), prostate cancer (HR 0.88, 95% CI 0.83-0.94). Individuals with loneliness had a significantly increased risk of cancer of urinary tract (HR 1.19, 95% CI 1.01-1.40), but a reduced risk of cancer of skin (HR 0.76, 95% CI 0.61-0.93).

Conclusions: Social isolation and loneliness were independently associated with incident cancer, with implications for early effective cancer prevention.