Do basal cell carcinomas recur after complete conventional surgical excision?

For 1378 patients treated in the 11 years 1988-1998 by conventional excision of 1635 basal cell carcinomas, 1516 first index lesions were histologically completely excised. All patients having more than one BCC excised were identified from the data base from 1988 to 2003 to give minimum 5 years follow for last treated primary lesions in 1998. Measured clearance margins around the initial lesions at or near sites of presumptive recurrent lesions were noted and the lesions recorded photographically. All incompletely excised lesions whether or not re-excised were excluded. The median age for all patients was 70 years. Over minimum 5 years follow up, six patients developed nine subsequent lesions contiguous with the scar or graft repair of primary index lesion excision site (probable recurrences). The median interval to recurrence was 41 months (4 months-8 years 10 months), with median lateral clearance margin around the primary tumour of 2 mm (0.3-6.8 mm). A further nine patients developed 11 new lesions near (within 1cm of) the scar or graft of primary index lesion excision site (possible recurrences). The median interval to recurrence was 59 months (1 year-8 years 6 months). The median lateral clearance margin around the primary tumour was 4.1 mm (0.8-5.8 mm). For the two groups combined the maximum recurrence rate expressed as a percentage of index lesions was 1.3% (20/1516). Two thirds of possible and probable recurrences occurred in the temple and forehead, although these sites represented only 22% of all lesions, which may rather suggest new lesions in an area of field change as opposed to residual disease. The measured clearance margins reported here perhaps suggest that some original lesions may well have been completely excised primarily and many 'recurrences' were new primaries. These figures indicate there is a low order of probability for the incidence of recurrent basal cell carcinoma during minimum 5 years follow period after conventional surgical excision and conventional histological assessment of tumour resection margins.