Features of cancer in teenagers and young adults in primary care: a population-based nested case-control study.

BACKGROUND: Teenagers and young adults (TYA, 15-24 years) diagnosed with cancer report repeated visits to primary care before referral. We investigated associations of symptoms and consultation frequency in primary care with TYA cancers. METHODS: Population-based, case-control study was carried out using data from the Clinical Practice Research Datalink (CPRD). A total of 1064 TYA diagnosed with cancer were matched to 13,206 controls. Symptoms independently associated with specific cancers were identified. Likelihood ratios (LRs) and positive predictive values (PPVs) were calculated. RESULTS: In the 3 months before diagnosis, 397 (42.9%) cases consulted > or =4 times vs 593(11.5%) controls (odds ratio (OR): 12.1; 95% CI: 9.7, 15.1), yielding a PPV for any cancer of 0.018%. The LR of lymphoma with a head/neck mass was 434 (95% CI: 60, 3158), with a PPV of 0.5%. Corresponding figures in other cancers included - LR of leukaemia with lymphadenopathy (any site): 29 (95% CI: 8, 112), PPV 0.015%; LR of CNS tumour with seizure: 56 (95% CI: 19, 163), PPV 0.024%; and LR of sarcoma with lump/mass/swelling: 79 (95% CI: 24, 264), PPV 0.042%. CONCLUSION: Teenagers and young adults with cancer consulted more frequently than controls in the 3 months before diagnosis. Primary care features of cancer match secondary care reports, but were of very low risk; nonetheless, some features increased the likelihood of cancer substantially and should be taken seriously when assessing TYA.