WHAT ARE BASAL CELL CARCINOMAS?
Non-Melanoma Skin Cancers (NMSC)
We live in an age of increased awareness of the linkages between genetics, skin type, ultra-violet light exposure and the development of skin cancer. Among the general public, melanoma receives the bulk of attention in this area as a tumour (of melanocytes) that demonstrates early metastasis relative to its tumour burden. However, melanoma represents less than 2-5% of all cutaneous malignancies. The other 95-98% are the non-melanoma skin cancers (NMSC) and as a group, these are the most common form of cancer in humans. The vast incidence of the NMSC within humans is often under-represented in cancer rankings. NMSC is usually excluded from these rankings by mention in the fine print of cancer fact sheets. Recent estimates demonstrate that more cases of NMSC have occurred in the past 30 years than all other forms of cancer combined. Basal cell (BCC) and squamous cell carcinoma (SCC) are the most common forms and account for the vast majority of NMSC. Despite growing public awareness campaigns of the harmful effects of ultraviolet (UV) exposure, the incidence of NMSC has been rising by 3-8% per year since 1960. This trend is predicted to continue as populations age worldwide. Despite this increase, the death rate from NMSC is decreasing due to increased awareness, earlier diagnosis and improved treatment options. A thorough understanding of the non-melanoma skin cancers and current management options is essential to continue this important survival trend.
Basal Cell Carcinoma (BCC)
Basal cell carcinoma is a malignant neoplasm of keratinocytes that is exceptionally common (>80% of skin cancers) and rarely metastatic. In the United States it affects 1 million people each year. BCC’s can be sporadic or related to heritable mutation(s). Most BCCs are sporadic with environmental exposures being the major causes with a latency period of anywhere between 20-50 years from exposure to the development of BCC’s. For this reason, most sporadic BCC’s occur in older males (>50years) with fair complexions, as this group has the greatest lifetime exposures to environmental influences.
Intensive, intermittent UV exposure (particularly UVB rays) resulting in sunburn and blistering (especially during childhood/adolescence) is a major risk factor for BCC. Fair skin types and individuals in hot sunny climates are at greater risk of incidental intermittent sunburn. In Australia which experiences the greatest UV solar irradiation per area of any continent, these factors combine to produce the highest incidences of non-melanoma- skin cancers and melanoma in the world. Additional environmental factors include tanning bed use, chronic inflammation (burns, scars), ionizing radiation, arsenic and hydrocarbon exposure.
Clinical Presentation and Classification:
BCCs usually present on sun-exposed areas, such as the head and neck, although they can occur at more photo-protected sites, particularly in the immunosuppressed. Superficial BCC’s typically appear on the trunk as single or multiple well-defined erythematous finely scaled patches or plaques with pearly edges. They can be confused with actinic keratosis, superficial squamous cell carcinoma or eczema. Any solitary patch of “eczema” not responding to treatment should raise suspicion for superficial BCC. Numerous superficial BCCs have a well-known association with a history of arsenic exposure. Nodular BCC’s are the most common subtype (50-85% of tumors) typically presents as a pearly papule or nodule with raised, rolled edges and telangiectasia. Ulceration may sometimes be present, hence the term ‘rodent ulcer’ and if left untreated local invasion can occur.
Course and Prognosis:
BCCs grow slowly, doubling in size after 6-12 months. Individuals presenting with one BCC are at increased risk of having more lesions at the time of diagnosis and a 3-year cumulative risk for a second primary of 44%. They can be locally invasive, involving subcutaneous tissue, muscle and bone. Long-term follow-up and annual skin examinations are warranted in those with a history of BCC, as they are also at an increased risk of developing other skin cancers. Diagnosis of BCCs can be done by dermoscopy or a biopsy.
Complete surgical excision with pathology confirmation remains the gold standard in the management of basal cell carcinoma. Surgical excision for basal cell carcinoma produces cure rates in excess of 90%. A meta-analysis (89 studies and 16,000 lesions) identified that a 3mm clinical margin for non-morpheaform BCC resulted in a cure rate of over 95% for lesions under 2cm in diameter. Incomplete excision in this study was associated with a 27% recurrence rate. While this is somewhat high, incompletely excised lesions often do not show any additional tumour on re-excision and such re-excision usually results in cure in this rarely –metastatic tumour. Standard surgical excision is one of the most widely used and reliable approaches to achieve definitive tumour excision with confirmatory histopathology in a relatively cost-effective manner. Standard surgical excision remains the workhorse for definitive BCC excision and is one of the most cost effective means to manage the millions of BCC’s that occur worldwide every year.
Skin Cancer Surgery at Panthea Clinics
At Panthea Clinics, we specialise in skin cancer treatment to ensure that every one of our patients has the best chance at overcoming this difficult disease. Lead by some of the best medical professionals in the field, we are proud to be a leading skin cancer clinic throughout the country.