Management of head and neck basal cell carcinoma from an ENT perspective

Jacqueline SW Chan 曾詩慧

HK Pract 2024;46:96-99

Summary

摘要

Introduction

Skin cancers are divided into melanoma and non-melanoma types. In Hong Kong, the incidence of non-melanoma skin cancer ranks eighth and ninth in male and female cancers respectively in 2019 according to the Hong Kong Cancer Registry.¹ The median age is 67 years and 75 years in male and female, respectively. Overall, it ranks eighth among the top ten commonest cancers in Hong Kong in 2019. The incidence rates across age groups have been stable over the years 2011- 2020 (overall crude incidence rate 13.6 per 100,000 persons). The Hong Kong Cancer Registry does not record the incidence of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) individually.

In a 10-year retrospective study of non-melanoma skin cancer in Hong Kong Chinese patients published in 2001, it was found that pigmented basal cell carcinoma was the most common type of non-melanoma skin cancer (60.1%) in Chinese patients, in contrast with rodent ulceration in Caucasians. The head and neck region was the most common site of BCC and SCC occurrence.² This article will thereafter focus on basal cell carcinoma of the head and neck region

Risk factors and genetics

The incidence of basal cell carcinoma is associated with increasing age, fair skin, ultraviolet light exposure and radiation.³ A rare germline autosomal dominant genetic condition, naevoid basal cell carcinoma syndrome (also known as Gorlin syndrome), is associated with multiple (more than 5 in a lifetime) and/or early onset (before age 30 years) BCCs and other syndromal features.⁴ Other genetic syndromes associated with an increased risk of BCC include xeroderma pigmentosum, Bazex-Dupre–Christol syndrome and Rombo syndrome.⁵

Clinical presentation

Patient typically present to the medical professional with a progressively enlarging skin lesion over a few months to a few years. As ENT practitioners, the lesions referred to us are usually over the nasal region, less commonly over the pinna and face in general. Approximately 70% of BCCs appear on the face and 15% on the trunk. Very rarely is BCC diagnosed in other areas such as the penis or perianal skin.

In general, 95% of BCCs, if recognised early, are ‘easy to treat’, however, in the following specific clinical scenarios BCCs might require a more comprehensive assessment, such as a thorough search for other coexisting skin malignancy and to arrange imaging for any regional lymph node metastasis.:

> Locally aggressive BCCs with cosmetic and functional deficit at baseline or anticipated after treatment, such as at the nose and eyelids.

> BCC recurrence in previously irradiated skin

> Metachronous BCC recurrence on the face requiring wide local excision and reconstruction

> Patient has underlying medical co-morbidities that interfere with treatment

In general, BCC is classified into low risk and high risk types as follow:-

Low risk BCC:

• Tumours < 2cm in diameter on trunk and extremities excluding the genitalia, hands and feet
• Nodular and superficial histopathology
• Lack of perineural invasion
• Primary lesion
• No prior irradiation
• Immunocompetent patient

High risk BCC:

• Tumours of ANY size in the head and neck region
• Tumours > / = 2 cm in diameter on trunk and extremities excluding the genitalia, hands and feet
• Aggressive histological subtype: morpheaform, sclerosing, mixed infiltrative, carcinosarcomatous
• Perineural invasion
• Recurrent lesions
• Previously irradiated skin
• Immunocompromised patients (e.g. HIV, AIDS, congenital disorders, autoimmune disorders)

Diagnosis

BCC is usually recognised via clinical inspection, especially for nodular, superficial, ulcerated subtypes, but in some cases a dermatoscope may aid in the diagnosis.⁶ Dermatoscopy is a non-invasive method that helps to visualise dermatopathological features that are otherwise not apparent to the naked eye. Examples of these dermatopathological features include maple-leave like area, arborising vessels and ulceration. Another non-invasive diagnostic method is the reflectance confocal microscopy (RCM) which has been shown to have a higher sensitivity and specificity as compared to visual inspection combined with dermatoscopy.⁷ RCM is a non-invasive imaging of the skin that provides cellular level magnification. With expertise the RCM images findings can correlate with an array of histopathological diagnoses, which, in turn, can differentiate lesion types before a biopsy.

In my practice, I always perform an incisional biopsy or a punch biopsy before definitive treatment, because the histological subtype may have a bearing on the choice of treatment. For example, high risk BCC would not be suitable for ablative superficial treatment that does not allow for assessment of the clearance of margins. Another reason favouring an incisional biopsy as opposed to excisional biopsy is that for small tumours, if completely excised and the pathology comes back to be malignant, it is crucial to ensure clear resection margins. For small tumour post excisional biopsy, owing to the rapid regeneration of the skin especially in the head and neck region, or the uncertain lag time between first biopsy and subsequent wide local excision, it can be difficult to localise the initial tumour hence the assessment of resection margin may be flawed. For this reason, pre-operative photographs before biopsy is an essential part of any management plan.

Management and various approaches

Surgery

In many literatures the preferred first line treatment of BCC is often by MOHS Micrographic Surgery (MMS), which is the gold standard for treating BCC⁸ especially when the location of the tumour predisposes the patient to cosmetic and functional concerns. The tumour is excised and immediately processed for histological evaluation. This process is repeatedly done until a negative margin is achieved, while minimising the amount of normal tissue to be excised. This method spares the patient from potential functional deficit, especially at specific regions such as the eyelid and the lips. The downside of this method is that it is not widely available, as it is a labour intensive procedure, and it either requires the operating surgeon to have specific pathological training or it requires the presence of a dermatopathologist.

A less labour intensive method while ensuring clear resection margins is to perform a staged excision with complete circumferential peripheral and deep margin assessment. The lesion is excised and the margins are formalin fixed for pathological examination. Once the margins are reported as clear, the skin defect can be reconstructed at a second stage. This method is less labour intensive and is generally available in every practice, but the downside is that a partially healed skin defect may present with some scarring tissue that potentially makes mobilisation of surrounding soft tissue for wound closure more difficult.

The excision margins depend on the risk profile of each individual BCC case.⁹ For low risk BCCs, safety margin of 3 – 4 mm is recommended while in high risk BCCs, when MMS is not available, the safety margin between 5mm and 15mm should be chosen based on individual tumour characteristics, such as the location of the tumour, medical co-morbidities, any presence of perineural invasion etc. Previous studies have shown that for BCCs that are less than 2 cm, a margin of 4mm would have an eradication rate of 98%, therefore even with greater margins there would be of minimal additional benefit.¹⁰

Topical eradication and clearance

A topical destructive tissue-removal is another but not the primary treatment for BCCs. There are two main reasons for this: firstly, histological examination and controlled margin clearance is not possible with topical or destructive treatment; secondly, the deeper part of the tumour may not be reachable as the more superficial layer of the tumour may be scarred during the topical treatment.

Furthermore, the efficacy of various destructive methods is highly dependent on operator skills and tumour characteristics, which means patient selection is very important for achieving favourable outcome.

In a study of 284 patients whose BCCs were treated with curettage and electro-dessication, incomplete clearance occurred in 10.3 % of the cases.¹¹ As per the European consensus-based interdisciplinary guidelines published in 2019, there is a 100% consensus to avoid topical or destructive treatment modalities in BCCs at risk of recurrence.

In those patients where surgery is not expected to give optimal result, radiotherapy may be a better option.

Radiotherapy

Radiotherapy is a valid alternative to surgery and the risk of radiation induced second malignancy is negligible. Radiotherapy is an option when the patient is not a surgical candidate with his or her coexisting medical comorbidities, or when the site of lesion poses significant functional and cosmetic deficit post excision. A systematic review has demonstrated that the recurrence rate of primary BCCs treated with radiotherapy has a recurrence rate of 3.5%, which is comparable with standard surgery and MMS (3.8%).¹² External beam radiotherapy (EBRT) is the most used radiotherapy modality, while brachytherapy is an alternative. Radiotherapy is also an option when there is microscopic or macroscopic residual tumour and if reresection is not the best option.

For low risk BCCs treated appropriately, the risk of recurrence is low. Patients with high risk BCCs should be counselled and advised to come back if they notice any new skin lesions. Long term follow-up is sometimes not the most pragmatic as recurrent disease may take up to 5 years to be clinically observable. In general, patients with high risk BCCs would benefit from interval follow-up every 6-12 months for 3-5 years.

Last consideration

Owing to the unique anatomy and functional concern in the head and neck region, skin lesions, in most cases, BCCs, often require careful planning and reconstruction. Primary closure after excision is the ideal situation but not always the case. Healing by secondary intent, that is, allowing the skin defect to granulate, may predispose the patient to unsightly scarring and distortion of facial symmetry. In many cases of primary BCCs appearing on the nose or pinna region, a local flap is needed for reconstruction in order to avoid the distortion of anatomy and function. For more complex lesions requiring extensive reconstruction, it is best dealt via a multidisciplinary approach, such as by ENT surgeons subspecialising in facial plastic surgery, head and neck specialists, oncologist, and dermatopathologist.

In conclusion, BCCs are common, slow growing skin malignancy that may first present to general practitioners. If treated timely, the prognosis is excellent. With careful treatment planning, there is also minimal risk of cosmetic or functional sequalae.

References

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