A DIFFERENT DRUM
DR. MALAYA SANTOS
Dr. Malaya Pimentel-Santos is a long-time community health advocate, having worked with several non-government health organizations. She is a fellow of the Philippine Dermatological Society and a professor of microbiology at the St. Luke’s College of Medicine.
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“Currently, between 2 and 3 million non-melanoma skin cancers and 132,000 melanoma skin cancers occur globally each year. One in every three cancers diagnosed is a skin cancer and, according to Skin Cancer Foundation Statistics, one in every five Americans will develop skin cancer in their lifetime.” – World Health Organization
Skin cancer is one of the most common types of cancer worldwide. Sun exposure – particularly in light-skinned individuals – is the primary risk factor. A new or changing skin growth, bump or sore; a wound that does not heal; enlargement, pain or itching in a ‘mole’ or nevus; new moles that appear in adult life; and the ABCDs of melanoma (see below) are warning signs that should merit a visit to a your doctor for further evaluation. Early diagnosis and appropriate management will help prevent complications. In the Philippines, the Philippine Dermatological Society has a registry of board-certified dermatologists and skin specialists nationwide, and can be viewed at www.pds.org.ph.
Although there are many types of skin cancer, they are often categorized (for simplicity) as either melanoma or non-melanoma cancers. Of these, malignant melanoma is more dangerous and deadly, due to its propensity to spread (metastasize) to distant organs. In many instances, pre-malignant skin changes begin to appear before the development of frank skin cancer. Pre-cancerous lesions include dysplastic (atypical-looking) moles and solar or actinic keratoses (crusty, scaling patches on a background sun-damaged skin). A personal or family history of skin cancer and recreational or occupational sun exposure all increase the risk for skin cancer.
Ultraviolet light and sun damage
Ultraviolet (UV) rays are not visible to the naked eye, but are nonetheless present in sunlight, tanning beds and some types of light bulbs. UV rays penetrate into the skin and induce malignant transformation of the skin cells, leading to skin cancer. Visible signs of long-term sun damage: premature wrinkles and mottled pigmentation should make us more watchful and suspicious of malignancy.
Darker skinned individuals are less at risk, because the melanin pigment in their skin serves to protect it from the harmful effects of UV light. The Filipino cultural preference for light skin also helps, because we generally avoid sun exposure, in order to keep our skin lighter. Although the aesthetic basis for this may be arguable, it is a scientific fact that avoiding the sun is much safer than exposing one’s skin to UV light in sun lamps and tanning beds as practiced by fair-skinned individuals.
While excessive sun exposure is harmful to everyone, susceptibility to damage from UV rays – and thus risk for developing skin cancer – is greatly influenced by skin color, which is, in turn, determined by the amount of melanin pigment. Light-skinned individuals residing in tropical climates exposed to intense sunlight are particularly at risk for skin cancer. Global warming and progressive destruction of the ozone layer have also contributed to a relative increase in the amount of UV light we are all exposed to today.
In the mid-1970s, Dr. Thomas Fitzpatrick formulated a classification system consisting of six distinct skin types based on skin, hair and eye color, as well as the likelihood of developing a sunburn (as opposed to a suntan) after sun exposure. Skin types I-II: light-skinned, freckled, blonde- or red-haired, blue- or green-eyed individuals have the greatest risk. Conversely, the darkest skin types V-VI: those who tan and rarely or never get sunburned have a relatively lower risk of developing cutaneous malignancies.
Malignant melanoma arises in pigment-producing cells called melanocytes. It has the potential to be life threatening due to its ability to metastasize to distant organs. Melanomas resemble moles, and some arise in preexisting moles. A simple way to remember the warning signs of melanoma is the mnemonic ABCD: Asymmetry, Border irregularity, Color variegation, and Diameter greater than 6 mm.
The non-melanoma cancers basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are derived from the cells of the epidermis, the topmost layer of the skin. They are commonly found on sun-exposed areas, and despite being locally destructive and disfiguring if untreated, they are less likely to metastasize and are rarely fatal. Three out of four cases of non-melanoma cancer are BCCs, the most common type of skin cancer.
In darker skinned individuals, BCCs and SCCs can have a pigmented appearance, and are sometimes mistaken for malignant melanoma. A diagnosis of skin cancer is confirmed by doing a skin biopsy (taking a small sample of skin and examining it under the microscope).
Most cases of skin cancer are preventable; most are curable if diagnosed early. As the weather begins to get warmer and we start planning our summer trips to the beach, let us keep in mind that the best and easiest way to avoid skin cancer is to protect ourselves from the sun, especially between the hours of 10am and 2pm. In the summer (and all year round), we must religiously use sunscreens, hats, umbrellas, and other forms of sun protection. Increased awareness of the risks and warning signs will help ensure early detection and treatment.
For more information on skin cancer, refer to www.cdc.gov and www.mayoclinic.org.