Non-melanoma skin cancers (NMSC), particularly basal cell carcinoma (BCC) are the most common cancers , where they are associated with significantly increased morbidity and mortality. The mainstay of treatment for BCCs is surgical excision, with clear published guidelines for advised margins. Clear margins have been shown to result in complete removal of the tumour and a reduction in recurrence rates. Despite this, there is clear evidence that approximately 30-40% of NMSC excisions result in close or involved margins, however the reasons for this remain unelucidated.
We undertook a retrospective analysis of head and neck BCC excisions at single plastic surgery unit in a tertiary public hospital in Australia to investigate the rates of close or involved margins and any associated factors. Specifically, we examined factors including histological subtype, anatomical location on the head and neck, lesion diameter and depth, and the presence of perineural invasion or lymphovascular invasion. This study was approved by the Human Research Ethics Committee of Tasmania (H0018554)
The rate of incomplete or close excision was greater with more invasive subtypes of BCC such as infiltrating (OR = 2.91, p = 0.0008) and sclerosing (OR = 3.65, p <0.0001) as well as those occurring on the external ear (OR = 3.00, p = 0.0001). This data supports the published literature. Additionally, increased lesion diameter (p <0.001) and lesion depth (p<0.001) are strongly associated with higher incomplete excision rates in BCCs. To our knowledge, this has not previously been reported.
In conclusion, BCCs with more aggressive histological subtypes were more likely to be incompletely excised, as were those located on the external ear and with greater diameter and depth. These findings could potentially advise margin guidelines for head and neck BCC excision.