Skin Cancer Screening (PDQ®): Screening - Health Professional Information [NCI] - Description of the Evidence
Evidence of Benefit Associated With Screening
More than 90% of melanomas that arise in the skin can be recognized with the naked eye. Very often there is a prolonged horizontal growth phase during which time the tumor expands centrifugally beneath the epidermis but does not invade the underlying dermis. This horizontal growth phase may provide lead time for early detection. Melanoma is more easily cured if treated before the onset of the vertical growth phase with its metastatic potential.
The probability of tumor recurrence within 10 years after curative resection is less than 10% with tumors less than 1.4 mm in thickness. For patients with tumors less than 0.76 mm in thickness, the likelihood of recurrence is less than 1% in 10 years.
A systematic review of skin cancer screening examined evidence available through mid-2005 and concluded that direct evidence of improved health outcomes associated with skin cancer screening is lacking.
However, this does not mean that skin cancers (whether melanoma or nonmelanoma) are unimportant or can be neglected without adverse consequences. When neglected, skin cancers can be disfiguring and/or cause death. Skin cancers are easily detected clinically and are often cured by excisional biopsy alone.
Various observational studies exploring the possibility that melanoma screening may be effective have been reported. An educational campaign in western Scotland, promoting awareness of the signs of suspicious skin lesions and encouraging early self-referral, showed a decrease in mortality rates associated with the campaign. In northern Germany, one region that received a skin cancer screening program during 2003 and 2004 was compared with four nearby regions that received no skin cancer screening program.[20,21] The two-stage skin cancer screening program began with a total-body visual examination of the skin by a general practitioner; if skin cancer was suspected, the patient was re-examined by a dermatologist. Nineteen percent of all those eligible were screened. The melanoma mortality rates were decreased in the years after the screening program in the screened region (1.7 per 100,000 in 1998–1999 to 0.9 per 100,000 in 2008–2009), whereas the melanoma mortality rates either stayed the same or increased in the comparison regions. Because of numerous methodological limitations such as the lack of randomization, lack of an internal control group, and relying on the region-level data rather than individual-level data to assess outcomes, these data provide only very weak evidence that the screening program reduced mortality from melanoma. Further, a thorough consideration of the harms was not provided, such as the harms associated with false-positive tests and overdiagnosis. (Refer to the Evidence of Harm Associated With Screening section in the Description of the Evidence section of this summary for more information.) Of note, four out of five skin lesions excised in the screening program were found to be benign.[20,21]