Selection of men for investigation of possible testicular cancer in primary care: a large case–control study using electronic patient records

Elizabeth A Shephard, William T Hamilton

Testicular cancer incidence has risen over the last two decades and is expected to continue to rise. There are no primary care studies on the clinical features of testicular cancer, with recent National Institute for Health and Care Excellence (NICE) guidance based solely upon clinical consensus. To identify clinical features of testicular cancer and to quantify their risk in primary care patients, with the aim of improving the selection of patients for investigation. A matched case-control study in males aged ≥17 years, using Clinical Practice Research Datalink records. Putative clinical features of testicular cancer were identified and analysed using conditional logistic regression. Positive predictive values (PPVs) were calculated for those aged <50 years. In all, 1398 cases were available, diagnosed between 2000 and 2012, with 4956 age-, sex-, and practice-matched controls. Nine features were independently associated with testicular cancer, the top three being testicular swelling (odds ratio [OR] 280, 95% confidence interval [CI] = 110 to 690), testicular lump (OR 270, 95% CI = 100 to 740), and scrotal swelling (OR 170, 95% CI = 35 to 800). The highest PPV for 17-49-year-olds was testicular lump, at 2.5% (95% CI = 1.1 to 5.6). Combining testicular lump with testicular swelling or testicular pain produced PPVs of 17% and 10%, respectively. Testicular enlargement carries a risk of cancer of 2.5% - close to the current 3% threshold in UK referral guidance. Contrary to traditional teaching, painful testicular enlargement may signify cancer. Some initial hydrocele diagnoses appear to be wrong, with missed cancers, suggesting an ultrasound may be useful when a hydrocele diagnosis is uncertain. These results support the existing NICE guidelines, and help to characterise when an ultrasound should be considered in symptomatic men.