Skin cancer is a malignant tumor that starts in the skin. It mainly comes in three types: basal cell carcinoma (the most common, slow-growing, and rarely spreads), squamous cell carcinoma (more likely to spread), and melanoma (the least common but the most dangerous, with a strong ability to spread). Skin cancer rates in Asian populations are lower than in Western populations, but melanoma often appears in places that get less sun, such as the palms, soles, and under the nails, making it easier to overlook.
Skin cancer is a cancer you can see — it grows on the surface of the body, so it should have the best chance of being found early. Learning to notice changes in your skin is the most practical line of defense.
Causes and Risk Factors
Ultraviolet (UV) radiation is the most important cause of skin cancer: long-term sun exposure, having had severe sunburns (especially in childhood), and using tanning beds all increase risk. Fair skin, having many moles, a weakened immune system (such as taking anti-rejection drugs after an organ transplant), and long-term exposure to arsenic or certain chemicals are also risk factors.
In Asian populations, melanoma is less strongly linked to sun exposure and more often appears on the soles, palms, and under the nails. Its causes may be related to genes and chronic irritation. No matter your skin tone, sun protection is a worthwhile habit; and if you have a family history of melanoma, you should have your skin checked regularly.
Common Symptoms and Warning Signs
To recognize melanoma, remember the ABCDE rule: A (Asymmetry), B (Border) irregular, C (Color) uneven or unusual, D (Diameter) larger than six millimeters, E (Evolving) changing over time (growing, itching, bleeding). A dark vertical streak in a nail or a black spot on the sole that keeps enlarging should prompt a medical visit.
Basal cell carcinoma often appears as a small, pearly bump or an ulcer that does not heal, usually on the face; squamous cell carcinoma often appears as a rough, crusted, easily bleeding lump. Any skin wound that does not heal within four weeks deserves a doctor's look.
Diagnosis and Staging
A dermatologist will use a dermoscope to magnify and examine the pigment structures of the lesion. If it looks suspicious, a biopsy is done to confirm the diagnosis — a biopsy is a simple outpatient procedure and does not cause cancer to spread, so there is no need to avoid it.
The key to staging melanoma is tumor thickness (Breslow thickness) and whether there is ulceration, lymph node involvement, or distant spread. The thinner the tumor, the higher the cure rate; for thicker tumors or those with lymph node spread, a sentinel lymph node biopsy and imaging evaluation are needed, and adjuvant (post-surgery) drug treatment may be considered.
Overview of Treatment Options
Surgical removal is the main treatment for all types of skin cancer: basal cell carcinoma and squamous cell carcinoma are usually cured after removal. For lesions in special locations, Mohs surgery can remove the cancer layer by layer to preserve as much normal tissue as possible. For cases that cannot be operated on, radiation therapy or topical drugs may be considered.
Drug treatment for melanoma has been completely rewritten over the past decade: about half of patients have a BRAF gene mutation and can use a combination of BRAF/MEK targeted drugs; immunotherapy (PD-1 inhibitors, or combined with CTLA-4 inhibitors) has even given some patients with advanced disease long-term control. Adjuvant treatment after surgery also benefits from targeted and immunotherapy drugs.
Clinical Trials: One More Treatment Option
Melanoma is a pioneer cancer type in immunotherapy research. New immune combinations, tumor-infiltrating lymphocyte (TIL) therapy, and cancer vaccines are all being advanced in clinical trials.
The CancerLink platform can screen for skin cancer clinical studies recruiting in Hong Kong based on cancer type, stage, and gene mutations. Once successfully matched and enrolled, study-related treatment costs are fully covered. Patients with advanced melanoma especially deserve to know about trial options.
Starting today, take one minute after a shower to look at your skin, including the soles of your feet and your nails. Protect yourself from the sun, pay attention to changes, and get checked if something seems wrong — when it comes to skin cancer, your eyes are the best screening tool.