Cancer in patients with mental illness – differences and outcomes


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Anna Gavin1, Suzanne Cromie1, David Donnelly1
1Queen's University Belfast, Belfast, UK

Background

Population estimates of pre-existing mental illness in patients with cancer, their care pathway and outcomes are unknown in the UK. We explore cancer occurrence, stage and survival in psychiatric patients compared to the general cancer population.

Method

Data from the NI Cancer Registry (2009-2011) for patients under 75 were linked to prescribing data and analysed by drug categories prescribed 3 months before a cancer diagnosis:

1. Anti-psychotic drugs (BNF code 4.2)

2. Hypnotics/anxiolytic or anti-depressant drugs (BNF codes 4.1 & 4.3) but not anti-psychotic drugs.

3. None of the above.

Frequency distributions between different drug categories were compared using z- and Chi-square tests, while survival analysis used the Kaplan-Meier and Cox regression methods.

Results

Of 20,426 cancer patients, 7.6% (male: 7.0%, female: 8.1%) received anti-psychotic drugs varying from 3.4% for malignant melanoma to 23% for stomach cancer; 34.9% (male: 29.9%, female: 40.3%) were prescribed hypnotics or anxiolytics and 29.5% (male: 23.3%, female: 36.3%) anti-depressants, while 55.4% (male: 61.1%, female: 49.2% female) had no psychiatric drug record. Mental health patients were more likely to be older and economically deprived. Oesophageal, stomach, gallbladder, pancreas, lung, ovary and brain cancers made up higher proportions of cancers diagnosed among mental health patients compared to those on no drugs, whereas non-melanoma skin, melanoma, breast, prostate, testicular and uterine cancer, leukaemia and lymphomas were lower . Patients prescribed anti-psychotic medication were more likely to have stage IV breast and colorectal cancers and lower survival. Breast cancer survival differences were accounted for by age and stage.

Conclusion

Cancer patients prescribed anti-psychotic drugs have higher tobacco related and brain cancers, lower skin, breast and prostate cancers, late presentation and lower survival despite frequent service contact. Awareness of cancer in psychiatric patients should be raised among relevant professionals. The poorer survival of this subgroup impacts on overall cancer survival.