Does screening by primary care providers effectively detect melanoma and other skin cancers?
EVIDENCE-BASED ANSWER:
Possibly. No trials have directly assessed detection of melanoma and other skin cancers by primary care providers.
Training a group comprised largely of primary care physicians to perform skin cancer screening was associated with a 41% increase in skin cancer diagnoses but no change in melanoma mortality.
Visual screening for melanoma by primary care physicians is 40% sensitive and 86% specific (compared with 49% and 98%, respectively, for dermatologists and plastic surgeons).
Melanomas found by visual screening are 38% more likely to be thin (≤ 0.75 mm) than melanomas discovered without screening, which correlates with improved outcomes.
Visual skin cancer screening overall is associated with false-positive rates as follows: 28 biopsies for each melanoma detected, 9 to 10 biopsies for each basal cell carcinoma, and 28 to 56 biopsies for squamous cell carcinoma. False-positive rates are higher for women—as much as double the rate for men—and younger patients—as much as 20-fold the rate for older patients (strength of recommendations for all foregoing statements: B, cohort studies).
A systematic review of 8 observational cohort studies with a total of 200,000 patients found a consistent linear increase in melanoma mortality with increasing tumor thickness.6 The largest study (68,495 patients), which compared melanoma mortality for thinner (< 1 mm) and thicker lesions, reported risk ratios of 2.89 for lesion thicknesses of 1.01 to 2 mm (95% CI, 2.62-3.18); 4.69 for thicknesses of 2.01 to 4 mm (95% CI, 4.24-5.02); and 5.71 for thicknesses > 4 mm (95% CI, 5.10-6.39).
The downside of visual screening: False-positives
The 2012 cohort study, which reported outcomes from 16,000 biopsies performed following visual screening exams, found that 28 biopsies were performed for each diagnosis of melanoma and 9 to 10 biopsies for each basal cell carcinoma.2 Diagnosis rates (number of skin biopsies performed for each case of cancer diagnosed) were equal in men and women for both types of cancer. However, researchers observed more biopsies for each diagnosis of squamous cell carcinoma in women than men (56 vs 28 biopsies per case).
Younger patients underwent more biopsies than older patients for each diagnosis of skin cancer. Women 20 to 34 years of age underwent more biopsies than women 65 years or older for each diagnosis of melanoma (19 additional excisions) and basal cell carcinoma (134 additional excisions). Women 35 to 49 years of age underwent 565 more biopsies for each diagnosis of squamous cell carcinoma than women 65 years or older. Similar patterns applied to men 20 to 34 years of age compared with men 65 years or older (24 additional biopsies per melanoma, 109 per basal cell carcinoma, and 898 per squamous cell carcinoma).
RECOMMENDATIONS
The US Preventive Services Task Force recommendations, based on a systematic review of mostly cohort studies, state that the current evidence is insufficient to assess the balance of benefits and harms of clinician visual skin cancer screening.7,8
The American Academy of Dermatology states that skin cancer screening can save lives and supports research on the benefits and harms of screening in the primary care setting.9
Continue to: Editor's Takeaway
