Surgical Management of Non Melanoma Skin Cancer

This section deals with the surgical management of basal and squamous cell carcinomas (BCCs and SCCs). No reference is made to the relative merits of non-surgical treatment options. Material has been drawn from a number of sources which attempt to give the dermatological surgeon useful information before embarking on a particular operation. They should not be seen as strict guidelines. Guidelines for the management of BCCs1 and SCCs2 have been drawn up by the BAD and these should be familiar to any dermatologist performing surgery.

When dealing with a patient with a tumour the first question is whether to treat at all (i.e. in cases of serious concomitant disease it may be more appropriate not to intervene). The desired outcome of surgery is generally a cure. However, occasionally debulking with a curette or using cryosurgery on extensive tumours can have a great impact on symptoms without offering any chance of a cure.

Basal Cell Carcinoma

When treating BCCs there are numerous options available. These include:

• Excision
• Mohs’ surgery
• Curettage and cautery (C&C)
• Cryosurgery
• Radiation therapy
• Photodynamic therapy
• Topical therapy (i.e. 5-FU, imiquimod)

An idea of practice among UK dermatologists for treatment of BCCs was obtained from a study by Motley et al3. Over a 2-week period in1993 the 166 UK dermatologists who responded treated 1366 patients with BCC (a total of 1597 BCCs). 58% of BCCs were treated by excision, 24% by C&C, 8% by cryotherapy, 8% by radiotherapy and 2% by ‘other’ means.

Which of these treatments offer the best chance of cure? A systematic review of treatment modalities for primary BCCs looked at all studies between 1970 and 1997 which prospectively examined recurrence rates in 50 or more patients with primary BCCs observed for 5 or more years4. The study concluded that Mohs’ surgery offered the lowest recurrence rate, followed by surgical excision. However, of the 298 studies examined, only 18 met the requirements for meta-analysis.

In addition to treatment, several factors independently affect the likelihood of cure. These are:

• Recurrent tumours (much harder to deal with)
• Anatomical site
• Size
• BCC sub-type
• Recurrent tumours

A study of recurrence rates of 5755 treated BCCs in 4324 patients showed that 15% of previously treated BCCs recurred within 5 years, compared to 10% of primary BCCs5. In addition, recurrent tumours are generally associated with greater morbidity.

Anatomical site

The ‘H zone’ on the face is often referred to as a site where tumours are most difficult to eradicate.

BCC sub-type

BCCs with a morphoeic growth pattern often have indistinct margins with a large extent of sub-clinical tumour invasion.

In each of these clinical scenarios surgical approaches with the highest cure rates should generally be used.

Which treatment to use?

Curettage and cautery (C&C) is a time-honoured treatment and is often repeated once or twice (double or triple C&C methods). In experienced hands there are reported cure rates of over 90%. However, C&C should probably be reserved as a treatment option only for well-demarcated primary tumours up to 1cm in diameter (higher for superficial BCCs), which are not in the ‘H zone’.

Excisional surgery with a scalpel is the most common method employed. What surgical margins should be used?

A crucial study in 1987 described pre-marking the skin around well-defined tumours with concentric circles at 2mm increments6. Following Mohs’ excision the extent of sub-clinical tumour invasion was calculated from the pre-surgical skin markings. A 4mm margin allowed complete excision of 98% of tumours

Larger BCCs, morphoeic sub-types and BCC recurrences will generally require even wider margins of excision (5-10mm recommended for recurrences). Mohs’ micrographic surgery (offering highly accurate yet conservative removal of BCC) should be strongly considered for these tumours (probable treatment of choice), and for BCCs in the ‘H zone’.

It is important not to diminish the width of the margin in order to improve the chance of a good cosmetic result, even if it becomes apparent that using a narrower margin does not result in a decrease in reports of complete excisions. The usual bread-loaf slicing used to view histological specimens only enables the pathologist to look at a minute fraction of the excision margins. A tumour with finger-like projections may appear to have been fully removed and reported as such.

Incomplete excisions

What do you do if the excision of a BCC is reported as being incomplete?

Various studies have shown that many BCCs reported as inadequately excised do not recur. However, if you look at the problem from a different angle the conclusions are at variance. An audit of 1392 excised BCCs, where 99 (7%) were histologically incompletely excised, found that residual tumour was reported histologically in 54% of the BCCs that were re-excised 7. There is a greater chance that a tumour with a positive deep margin will recur than a tumour with a positive lateral margin.

There seems little doubt that the body can clear residual tumour in some cases but at the same time it is recognised that some tumours show a remarkable ability to infiltrate widely, to spread along tissue planes, to invade cartilage and bone, to spread along nerves and arteries and wreak havoc. Our aim should be to clear tumours at the first procedure whenever possible.

Squamous Cell Carcinoma

Compared to BCCs, SCCs are more aggressive with a greater propensity to metastasise. A review of all studies since 1940 on the prognosis of SCC on the skin and lips found the following factors to be important:

• Site

• Size

Further factors, which render an SCC as a difficult or aggressive tumour, are:

• Tumours arising in areas of prior radiation or thermal injury, chronic draining sinuses, chronic ulcers or chronic inflammation – These tumours have the highest malignant potential.
• Tumours arising in non-exposed sites – These tumours have more malignant potential than those in exposed sites.
• Tumours greater than 4mm in depth or extending down to the subcutaneous tissue (metastatic rate 45.7%).
• Poorly differentiated tumours – 25% local recurrence; 16% metastasis; 61% 5-year survival (cf. 12%;6%;95% 5-year for well differentiated).
• Tumours with perineural involvement.
• Tumours arising in patients who are immunosuppressed.
• Tumours which are locally recurrent.

Which treatment to use?

Curettage and cautery has been reported in several series as offering excellent cure rates. Experience suggests it can be used for small (<1cm), well-differentiated, primary, slow growing tumours on sun-exposed sites. Generally, however, surgical excision is favoured and many authors lean towards use of Mohs’ excision for the majority of SCC.

Margins ranging from 2-10mm have been recommended depending on the size, site etc. In another study using marking of concentric circles prior to Mohs’ surgery, a 4mm margin would have been necessary to clear 95% of tumours. A diameter greater than 2cm, aggressive histology, and ‘high risk’ sites each called for 6mm to achieve the same benefit. Size greater than 2cm in a ‘high risk’ site needed a 9mm margin. This study was not looking at cure rates, but at excision of sub-clinical tumour spread.

The following table was published in the BAD ‘Guidelines for the management of cutaneous squamous cell carcinoma’:

The dermatological surgeon should use the evidence of the studies discussed above, along with published guidelines, to allow a better understanding of those factors which are likely to influence the success or otherwise of surgery for a particular tumour.

1. Telfer R, Colver GB, Bowers PW. Guidelines for the management of basal cell carcinoma. Br J Dermatol 1999;141:415-23.
2. Motley R, Kersey P, Lawrence C. Guidelines for the management of squamous cell carcinoma.
3. Motley RJ, Gould DJ, Douglas WS, Simpson NB. Treatment of basal cell carcinoma by dermatologists in the United Kingdom. Br J Dermatol 1995;132:437-40.
4. Thissen MR, Neumann MH, Schouten LJ. A systematic review of treatment modalities for primary basal cell carcinoma. Arch Dermatol 1999;135:1177-83.
5. Silverman MK, Kopf AW, Grin CM, Bart RS, Levenstein MJ. Recurrence rates of treated basal cell carcinomas. J Dermatol Surg Oncol 1991;17:713-8.
6. Wolf DJ, Zitelli JA. Surgical margins for basal cell carcinoma. Arch Dermatol 1987;123:340-4.
7. Griffiths RW. Audit of histologically incompletely excised basal cell carcinomas: recommendations for management by re-excision. Br J Plast Surg 1999;52:24-8.
8. Rowe DE, Carrol RJ, Day CL. Prognostic factors for local recurrence, metastasis, and survival rates in squamous cell carcinoma of the skin, ear, and lip. J Am Acad Dermatol 1992;26:976-90. 

9. Brodland DG, Zitelli JA. Surgical margins for excision of primary cutaneous squamous cell carcinoma. . J Am Acad Dermatol 1992;27:241-8.