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

Abstract

Background: In England and Wales, patients with suspected skin cancer are referred to specialists within 2 weeks ('two-week rule', TWR) by tick-box proforma.

Objectives: To evaluate proforma details that might be amended to improve sensitivity and specificity.

Methods: 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.

Results: 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.

Conclusions: 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.