Melanoma is a serious form of skin cancer originating in melanocytes, the cells that produce the pigment melanin. It is possible to have melanoma for years without knowing, particularly in its earliest stages. The initial, slow-growing phase can easily be overlooked for an extended period, leading to a delayed diagnosis. This prolonged, asymptomatic existence is why regular self-examination and professional screenings are strongly recommended.
Understanding Early Stage Growth
Melanoma’s early development involves two distinct growth phases. The initial phase is the radial growth phase, where cancerous cells spread horizontally, confined to the outermost layer of the skin (epidermis) or the top of the dermis. During this time, the lesion grows slowly, often mimicking a benign mole, and the risk of the cancer spreading to other parts of the body is extremely low.
The radial growth phase can persist for months or even several years. Eventually, the melanoma progresses to the vertical growth phase. In this phase, cells penetrate downward into deeper skin layers, forming a true tumor. This shift makes the cancer invasive and significantly increases the chance of metastasis. For superficial spreading melanoma, this radial phase may last four to 12 years before the vertical phase begins.
Subtle Indicators That Are Often Missed
The challenge in early detection lies in the subtle nature of the changes during initial growth phases. Many melanomas are first noticed because they follow the classic ABCDE warning signs:
- Asymmetry: One half of the spot does not match the other.
- Border irregularity: Edges are uneven, notched, or scalloped.
- Color variation: The spot contains multiple shades (black, brown, tan, red, white, or blue).
- Diameter: Spots larger than six millimeters (about the size of a pencil eraser) raise suspicion.
- Evolving: Any change in size, shape, color, or elevation.
An evolving spot may also begin to itch, bleed, or become tender, indicating active change. However, not all melanomas present with these traditional characteristics, making some types easier to miss for years.
Amelanotic melanomas, for example, lack significant pigment and can appear colorless, pink, or reddish. These lesions are often mistaken for benign conditions like scars or warts, leading to delayed diagnosis until they are more advanced. Other melanomas can appear in unexpected places, such as dark streaks under a fingernail or toenail, which are easily dismissed as a bruise.
Why Delayed Detection Increases Risk
Allowing melanoma to exist for years escalates the risk because of the progression to deeper invasion. The prognosis is directly tied to the Breslow depth, which measures the tumor’s thickness in millimeters from the skin’s surface to the deepest point of invasion. This measurement is the most important factor in determining a patient’s outcome.
If melanoma is caught while thin (less than one millimeter), the five-year survival rate is high, often between 95 and 100 percent. However, the longer the melanoma is present, the more likely it is to thicken and penetrate the dermis. Once the tumor thickness exceeds four millimeters, the prognosis declines substantially, with the five-year survival rate dropping to between 27 and 50 percent.
Increased depth correlates directly with the risk of metastasis, the spread of cancer cells to nearby lymph nodes or distant organs. As the Breslow depth increases, so does the likelihood of cancer cells entering the blood or lymphatic system. Delayed detection increases the risk of systemic disease and diminishes the chances of a successful cure.
Proactive Steps for Early Identification
Taking proactive steps for early identification is the most effective defense against the consequences of delayed detection. Dermatologists recommend performing a thorough skin self-examination every month to become familiar with the skin’s baseline appearance. This involves checking the entire body, including areas often missed, such as the scalp, the soles of the feet, and between the toes, using both a full-length and a handheld mirror.
The goal of these monthly self-checks is to identify any new or changing spots, especially those fitting the ABCDE criteria. Any lesion that is evolving, bleeding, or looks different from all other spots—sometimes called the “ugly duckling” sign—warrants immediate professional evaluation.
In addition to self-exams, scheduling regular full-body skin examinations with a dermatologist is advised, particularly for individuals with a history of sunburns, numerous moles, or a family history of melanoma. Dermatologists use specialized tools like a dermatoscope to examine suspicious lesions with magnification. These routine measures ensure that if melanoma is present, it is identified while still in its thin, highly curable radial growth phase.