The U.K. skin cancer 'two-week rule' proforma: assessment of potential modifications to improve referral accuracy.

Abstract

In England and Wales, patients with suspected skin cancer are referred to specialists within 2 weeks ('two-week rule', TWR) by tick-box proforma. To evaluate proforma details that might be amended to improve sensitivity and specificity. Five hundred and six TWR referrals were evaluated. Potential proforma changes were criteria for melanoma, and guidance that most squamous cell carcinomas (SCCs) measure >or= 1 cm. We compared melanomas vs. benign pigmented lesions using seven-point, and amended (10-point), checklist scores. We examined sizes of 82 SCCs and investigated influence of size on TWR referral. Of 506 TWR referrals, 381 (75%) were suspected melanoma [30 (7.8%) correct], and 125 (25%) were suspected SCC [22 (17.6%) correct]. Fifty per cent of melanomas were referred by TWR, but only 8% of SCC. No combination of seven-point checklist criteria had discriminatory value for melanoma; total scores (seven- or 10-point) were not significantly different between melanomas and nonmelanomas. No total score, using either system, had acceptable sensitivity and specificity. Measured size of SCCs varied from 4 to 30 mm; 88% were >or= 1 cm. Reducing the 'cut-off' to 7 mm identified only another 3.5%. Even at 2.5-3 cm, only 50% of SCCs were referred by TWR. The seven-point checklist for melanoma, when used in TWR format, does not have discriminatory value for melanoma. Altering the suggested cut-off size for SCC is unlikely to alter referrals. Education may be a more important factor in refining use of the TWR.