Cutaneous Squamous Cell Carcinoma – Overview

Squamous cell carcinoma (SCC) is defined by the World Health Organisation as ‘a malignant neoplasm of epidermal (and mucous membrane) keratinocytes in which the component cells show variable squamous differentiation.’

 

Most SCCs appear on the areas of the skin which get the most sun exposure though this is not the only place which the can arise. SCCs can also arise on mucosal areas such as on the lip. Patients who have a pale complexion and those who do not tan readily are at a greater risk. SCC is very uncommon in the Black population.

The most important causative agent is sun exposure, more correctly UVB radiation. Others factors that have been incriminated include human papilloma virus (HPV) infection, ulcers, immunosuppression and radiotherapy. Patients with organ transplants are also at a greater risk. SCC can be fatal in some cases (most commonly found in Australia) giving rise to the notion that sun exposure, which causes DNA damage and also suppresses the skin immune system, plays a lead role in the cause of aggressive SCCs. 

As sun exposure is the major cause factor of SCC, it is no surprise that the forehead, ears, scalp, face, neck, back of the hands and lips are the most common places to find SCCs on the human body.

SCCs commonly appear as plaques/nodules with an elevated/indurated, crusty surface. The areas immediately surrounding the SCC show the typical signs of sun damage.

I have previously blogged about the prognostic factors of SCC, please click on the link to see more (Prognostic Factors of Cutaneous Squamous Cell Carcinoma)

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Prognostic Factors of Cutaneous Squamous Cell Carcinoma

Below is a brief description of the prognostic factors involved with cutaneous squamous cell carcinoma, ie. SCC of the skin.

Site

The actual site of the SCC provides much prognostic information, most importantly that SCCs from sites such as the ear, lip and sole have an increased rate of metastasis.

Size

The physical size of the tumour is also related to prognosis, generally speaking the larger the tumour the poorer the prognosis.

Invasion

If the SCC is seen to be invasive this reflects a poorer prognosis. The actual depth of invasion is again prognostic, ie. the deeper the invasion, the poorer the prognosis.

Tumour differentiation

Histologically SCCs are graded for their differentiation with them being either well, moderately or poorly differentiated. The poorer the tumour differentiation, the poorer the prognosis.

Other

There are many other factors which can affect the prognosis of cutaneous squamous cell carcinoma including immune status of the patient, HPV infection status, age and genetic predisposition.

Thanks for reading

Keep an eye out for my website soon to be up and running (www.skinpathonline.com)

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My email is feedback@skinpathonline.com for any questions or queries.

Non-melanoma skin cancer (NMSC) treatments

Below are the most common treatments available, plus a brief description, once a NMSC has been diagnosed (usually a basal cell carcinoma or a squamous cell carcinoma).

Surgical excision (standard) – the most common and preferred form of treatment. Good for nodular tumours with a sharply demarcated border. Has a high cure rate and is dependent on the closeness of tumour to the resection margin in regards to the pathology (ie. the closer the tumour is to the margin the more likely it is to recur). One let down is the bread loafing technique which results in only approximately 5% of the actual margins being visualised by the pathologist for assessment of complete excision.

Moh’s /  Moh’s Micrographic Surgery – form of treatment with the highest reported cure rate (~97-99%). This technique results in the entire peripheral margins and the deep margins being visualised and assessed for completeness of excision (this is why the cure rate is so high). One let down is the time-consuming nature of the technique and the specialised training that is involved.

Topical chemotherapy – the most common available topical chemotherapy agents include 5-fluorouracil (5-FU) and 5% imiquimod. Generally speaking 5-FU works by inhibiting DNA replication therefore the growth of the tumour and imiquimod works by modifying the local tumour immune response of the patient. Advantages include the non-invasiveness topical therapy. Disadvantages are that, used alone, they can only be used on superficial tumours and not invasive tumours. Experimentation of their use in conjunction with other treatments (eg. curettage then topical treatment, or topical use to reduce tumour size before excision) have resulted in reports of higher cure rates.

Curettage +/- Electrodissection – put simply the tumour is physically scrapped away then the treated area is exposed to an electrical current which results in the softening of the skin and the procedure is repeated until the treating physician is satisfied excision is complete. The curettage portion technique can be applied alone without the electrodissection. This technique is usually reserved for site which are cosmetically unimportant (eg back). The cure rate is dependent on how aggressive the technique is applied (ie. the more the aggressive the higher the cure rate) and the growth type of the tumour being treated (ie. the more invasive the tumour the lower the cure rate).

Cryotherapy – one of the older treaments for NMSC which involves treatment of the tumour most commonly with liquid nitrogen. Cure rate can be high but there is reduced tumour margin control resulting in a higher recurrence rate.

Photodynamic Therapy (PDT) – fairly new technique which involves applying a topical photosensitizer to the target tumour and then exposure of the target area to light. This results in the production of aggressive chemicals which damage the cell causing death. Disadvantages include the ineffectiveness on invasive and thicker tumours due to lack of light penetration, and high cost. Advantages include the non-invasiveness of the technique.

Radiotherapy – usually reserved for older patients or where the surgical removal of the tumour is not a viable option. Has a reported cure rate of approximately 80-95%. Tumours recurring after radiotherapy are generally more aggressive and can become radiotherapy resistant.

I welcome any comments or other therapies you have encountered.

Keep and eye out for www.skinpathonline.com.

Follow me on twitter (@skinpathology)

My email is feedback@skinpathonline.com for any questions or queries.