Malignant skin tumors are one of the commonest cancers encountered in clinical practice, especially in people with light skin pigmentation. Symptoms and signs are apparent early in the course of disease, as they are often visible. Skin cancer incidence is rising in many parts of the world due to the rise in popularity of tanning and outdoor activities. Successful treatment is possible in the vast majority of cases and this entails complete tumor removal and reconstruction of resultant defects to ensure optimal functional and aesthetic restoration.
Skin tumors are usually painless in the early stages. They present as nodules or ulcers that may bleed on contact or may become infected. They often appear irregular and are hard to touch. Some skin tumors may spread to the adjacent lymph nodes in the intermediate and late stages of the disease. Pain may occur later in the disease due to infection or infiltration of deeper tissue layers. Melanoma, a type of skin cancer, may present with pigmented lesions arising within the skin of any part of the face, trunk, or extremities. These lesions have irregular, heterogeneous pigmentation and may be ulcerated. In Asian persons, melanomas may present in the palms, soles or underneath the fingernails or toenails.
Skin tumors may arise in previously normal skin, in chronic wounds (“Marjolin ulcers”), previous scars or previously irradiated skin or previous moles. Most cases of skin cancers arise in sun-exposed areas such as the scalp, face, neck and arms. They often arise in older individuals and in those with sun damage and light skin pigmentation. Affected individuals present with functional deficits and aesthetic deformities.
Basal cell carcinoma (BCC) is the most common malignancy in human beings and accounts for 80% of all skin cancer cases. Squamous cell carcinoma (SCC) is the second most common skin malignancy and accounts for 15% of skin cancer cases and may arise in chronic ulcers or normal skin. Melanoma is a less common tumour and occurs more frequently in individuals with lighter skin pigmentation.
Overexposure to the sun and ultraviolet radiation results in cumulative lifetime DNA damage and gene mutations. These lead to abnormal cell multiplication and behavior, and results in the formation of basal cell and squamous cell cancers. Other known risk factors for development of skin cancers include immunosuppression, chronic wounds, previous burn scars and previous radiation therapy to the skin. Melanomas may arise in normal skin or in a previous mole, although this is thought to be an uncommon occurrence.
BCC initially grows as superficial skin nodules or shallow ulcers but evolve with time to infiltrate deep tissues. BCC rarely spreads to other organ systems. Complete cure is possible in most cases and the prognosis is excellent.
SCC is a more aggressive disease than BCC and is capable of deep invasion earlier in the disease. SCC may potentially spread to lymph nodes, lungs, bones and liver. Early treatment of SCC is important in order to achieve complete tumor clearance, cure and good prognosis.
Melanoma also has an initial superficial spreading phase that quickly transforms into a vertical growth phase that causes deep invasion. In many cases, melanoma is more aggressive than BCC and SCC. It may spread to the surrounding skin causing satellite lesions, and to other organ systems including the lymph nodes, bones, liver and brain. Early treatment is treatment is imperative to achieve complete tumor control and cure.
Complete tumor clearance is possible in the vast majority of early and intermediate stage skin cancers and excellent prognosis may be attained. Skin tumors often extend beyond what the eye can observe and it is usual to remove the tumors with a margin of normal tissue to ensure that no tumor cells are left behind. Optimal treatment outcomes are obtained by complete tumor removal and preservation of critical structures where feasible, or reconstruction where they are excised. Surgical management of skin cancers is a fine art and strikes a balance between achieving complete tumor clearance and producing functional and aesthetic outcomes.
Treatment with medication, chemotherapy and radiation therapy is normally reserved for individuals who are not fit to undergo surgery or have advanced tumors.
The gold standard of treatment of all three skin cancers is surgical excision with clear margins. In the case of SCC and melanoma, the regional lymph nodes in the neck, underarm (axilla) or the groin may require removal if enlarged as well. Following tumor resection, there may be a large defect with exposed underlying structures and this may require immediate reconstruction during the same surgery.
Reconstruction is required under the following circumstances:
Small tumors in areas with lax skin may be excised and directly closed as ambulatory procedures under local anesthesia. Larger tumors or tumors growing in areas without sufficient skin laxity will require wide excision and reconstruction. In many cases, reconstruction may also be performed under local anesthesia with optional intravenous sedation if requested. Reconstruction may be achieved using a variety of skin grafts and flaps that are tailored to the individual case to ensure optimal match in contour, thickness and color of skin for exquisite postoperative outcomes. Lymph node excision may be required in cases of SCC and melanoma and additional incisions may be required in the neck, underarm (axilla) or groin for this purpose.
SCC and melanoma cases may require various scans to ascertain the tumor depth and if there is spread of disease to the regional lymph nodes. Individuals are advised to stop herbal supplements and traditional medicine 7 days prior to surgery to minimize bruising and swelling.
Local anesthesia is infused into the wound to ensure intra- and post- operative pain relief. The lesion is excised with a margin of normal tissue. Small lesions may be closed directly. Larger lesions are excised in accordance with the facial subunit principles, which site the scars between the naturally occurring junctions between the different parts of the face. Reconstruction is then performed using a variety of skin grafts or flaps taken from the adjacent skin or other parts of the body. Lymph node excision may be required in cases of SCC and melanoma. The excised tumor and lymph nodes are sent for histopathological reporting, and this will determine the success of tumor clearance.
Complete tumor clearance is achieved in the vast majority of cases. BCC and SCC cases do not require further treatment if surgical tumor clearance is complete. In cases where tumor clearance cannot be achieved, either due to advanced disease or proximity to critical structures (e.g. brain and eye), postoperative adjuvant chemotherapy or radiation therapy may be required.
Melanoma is an aggressive disease and adjuvant therapy often needs to be administered in advanced cases to improve survival outcomes. Adjuvant treatment with immunotherapy and chemotherapy in Stage III and IV melanoma has been shown to be beneficial for survival outcomes.
Most cases of BCC and SCC are often performed as ambulatory procedures under local anesthesia and most individuals are able to resume their work and daily activities on the following day. There is minimal postoperative swelling and bruising which mostly settles after 7 to 10 days. Larger SCC and melanoma cases are often performed under general anesthesia as inpatient surgeries requiring a short hospital stay.
Medical treatments are useful in cases of BCC where individuals are unfit for surgery, in very advanced BCC cases and rare cases of multiple recurrent BCCs (Gorlin syndrome). A new class of orally-administered drugs known as the Hedgehog pathway inhibitors (HPIs) specifically targets BCC is useful for treatment of difficult or advanced BCC cases. Medical treatment of BCC with HPIs is administered by partnering medical oncologists.
Radiation therapy uses high-energy ionizing radiation to cause DNA damage and kill cancer cells. Radiation therapy is useful in individuals who are unfit for surgery, in very advanced BCC and SCC cases that are in close proximity to critical structures (e.g. brain, eyeball) and in cases with positive tumor margins despite aggressive tumor resection. The role of radiation therapy in melanoma is still evolving. Radiation therapy is administered by partnering radiation oncologists.
Adjuvant therapy is beneficial in cases of advanced BCC and SCC and in stage III and IV melanoma. This is administered postoperatively and may include treatment with immunotherapy agents (specifically targeting melanoma cells) or traditional chemotherapy agents. These are administered by partnering medical oncologists.
Dr Yeo is a visiting consultant in a large restructured hospital runs a busy dermatologic surgery clinic in Singapore in addition to his private practice. He has accumulated extensive experience with the management of skin cancers. He is also an editor of various professional dermatologic surgery journals. He has authored peer-reviewed articles on skin cancer management and is current with the latest treatment modalities in the management of skin cancers. He is also active in educating fellow specialists in skin malignancies.