Table 9SKIN CANCER: diagnostic difficulties

AuthorSettingDescriptionNo.InclusionExclusionResultsQuality
Brochez, 2001BelgiumThis study aimed to compare the diagnostic abilities of general practitioners and dermatologists in Belgium concerning pigmented skin lesions in general and melanoma in particular. The study design was a ‘before and after’ evaluation of a health education programme for general practitioners. A test set of 13 pigmented skin lesions on 35 mm colour slides as presented to participating general practitioners and dermatologists during a monthly educational course.160 GP’s

60 dermatologists
All GPs educational groups in the province of East-Flanders, Belgium were invited to participate--The frequency of melanomas encountered was one in seven years for the general practitioners and one in eight months for dermatologists. Consultations for advice about pigmented lesions were encountered once in 30 days by general practitioners and once per day by dermatologists.
Sensitivity of general practitioners before the course in diagnosing melanoma from the slides was 72%, and 84% afterwards (dermatologists 91%). Specificity among general practitioners was 71% before and 70% after, and 95% among dermatologists. The positive predictive value (PPV) of general practitioners before was 61%, and 63% after (dermatologists 92%). The negative predictive value was 80% before and 87% after among general practitioners (dermatologists 95%).
Chen 2001USAThis systematic review was undertaken in order to compare the diagnostic accuracy and biopsy or referral accuracy of dermatologists and primary care physicians. Studies that presented sufficient data to determine the sensitivity and specificity of dermatologists’ or primary care physicians ability to correctly diagnose lesions suggestive of melanoma and to perform biopsies on or refer patients with such lesions. Studies published between January 1966 and October 1999 in MEDLINE, EMBASE and CancerLit databases were retrieved.32 studiesStrict criteria for inclusion were applied to ensure results were comparable across studies. Studies were selected if they presented sufficient data to determine the sensitivity and specificity of dermatologists’ or PCPs’ ability to correctly diagnose lesions suggestive of melanoma and to perform biopsies on or refer patienst with such lesions.--None of the studies reported specificity for dermatologists. One study reported specificity for primary care physicians (0.98). For biopsy or referral accuracy, sensitivity ranged from 0.82 to 1.00 (from five studies) for dermatologists and 0.70 to 0.88 (from six studies) for primary care physicians. The range of specificity was 0.70 to 0.89 (from three studies) for dermatologists and 0.70 to 0.87 (from four studies) for primary care physicians. Most of the studies included in the review evaluated only diagnostic accuracy and not biopsy or referral and did not report either sensitivity or specificity, and did not have an adequate sample size or describe the lesions shown to subjects.
Del Mar et al, 1995AustraliaRandomised controlled trial of an intervention to improve diagnostic abilities of GP’s. Australian practitioners were offered an algorithm and the use of an instant developing camera in a trial to test whether this intervention would reduce the number of benign melanocytic lesions excised from the skin. Doctors in the city randomised to receive the intervention were offered a protocol to assist in the management of any melanocytic lesion for which a diagnosis of malignancy was entertained.Control group: 45 general practitioners, seven surgeons and one dermatologist.

Intervention group: 48 general practitioners and four surgeons.

During the study, nine new doctors entered and two left the control community, and seven new doctors entered and five left the intervention community. All new incoming doctors agreed to take part except for one general practitioner in the intervention city.
The two cities were selected on the basis of their similarity.Doctors refusing to take part.. Reports from the previous six months were collected as a baseline to check that the excision rates of benign and malignant melanocytic lesions were comparable between the two cities. In the six months before the introduction of the intervention a total of 1358 melanocytic lesions were reported by the pathology laboratories: 752 (55%) from the control community and 606 (45%) from the intervention community.
More than a hundred practitioners in total participated in the study but no power calculation was given. During the 24 months after the intervention was introduced a total of 4465 lesions were excised in the two study cities, of which 1995 (45%) were excised in the intervention city, the same proportion as at baseline.
No significant difference in the percentages of benign lesions reported in the intervention and control cities before the algorithm and camera were used (93.6% and 94.0% respectively) but there was a significant difference afterwards (88.8% and 93.8%, P < 0.001). There was no difference in the percentage of invasive melanomas excised per month in the intervention city (3.4%) compared with control city (3.4%). Offering doctors a diagnostic algorithm and providing them with a camera reduced the relative proportion of benign naevi they removed
English, 2003AustraliaThis Australian randomised control trial was undertaken to determine whether the use of a camera and algorithm aided the diagnosis of pigmented skin lesions by reducing the ratio of benign lesions to melanomas in general practice. The trial built upon the earlier randomised control trial conducted by Del Mar et al (1995) in which participants were randomised by town rather than practice.

Intervention practices were given an algorithm and instant camera to assist with the diagnosis of pigmented skin lesions. All practices were given national guidelines on managing melanoma
223 practices participated.

468 general practioner participated in the trial.
General practioners on the mailing lists of the divisions of general practice in Perth were eligible. General practioners who joined a practice after randomisation or with whom no contact had been made before randomisation were also eligible.--During the two periods, the participants excised 8563 pigmented skin lesions: 295 (3%) melanomas (180 invasive and 115 in situ), 529 (6%) dysplastic naevi, 5065 (59%) other naevi and 2674 (31%) seborrhoeic keratoses. At baseline the ratios of benign to malignant lesions were lower in the intervention than the control group. During the trial period the ratios were higher in the intervention group (19:1 vs. 17:1 without seborrhoeic keratoses and 29:1 vs. 26:1 with seborrhoeic keratoses). After adjustment for patients’ age, sex and socioeconomic status, the ratio was 1.02 times higher (95% CI 0.68 to 1.51, P=0.94) in the intervention group when seborrhoeic keratoses were not included and 1.03 times higher (0.71 to 1.50, P=0.88) when seborrhoeic keratoses were included.
General practitioners in the intervention group were less likely than those in the control group to excise the most recent pigmented skin lesion they had managed (22% vs. 48%, P<0.001) and to refer the patient to a specialist. Neither group showed substantial changes in excision rates within practices between the baseline and trial periods. The overall rates showed little change in the control group, but decreased in the intervention group between periods largely because of substantial reductions in a few practices with large numbers of baseline excisions. The imbalance between practices was due to specialist general practitioners (to whom others refer patients with pigmented lesions and those who perform a substantial proportion of all excisions). Four of the total (five) were in the intervention group. When these general practitioners were excluded the number of benign lesions excised was similar.
Gerbert et al 1998USAThis study sought to determine whether a brief, multicomponent educational intervention could improve the skin cancer diagnosis of primary care residents to a level equivalent to that of dermatologists. The intervention comprised an interactive seminar, which included a slide show lecture, videotape and demonstrations on how to conduct a total body skin examination. This randomised control trial was suited to assessing the effects of an educational intervention with pre-test and post test measurements of residents’ ability to diagnose and make evaluation plans for lesions indicative of skin cancer. The pre-tests and post-tests consisted of lesions shown on slides, computer images, and patients.26 primary care residents were assigned to a control group and 26 to an intervention group, and 13 dermatologists completed a pre-test and post-test.Residents in primary care and family medicine.--No significant differences between control and intervention primary care residents on the demographic and dermatology experience variables or pre-test overall diagnosis and overall evaluation planning scores. The control group, the intervention group and the dermatologists all demonstrated improved performance over time, with the intervention group experiencing the largest gains. The intervention group showed significantly greater improvement than control in overall diagnosis and diagnosis of malignant melanoma and seborrheic keratosis. Intervention group primary care residents performed as well as the dermatologists on five of the six skin cancer diagnosis and evaluation planning scores with the exception of the diagnosis of basal cell carcinoma. The control group performed as well as the dermatologists on three of the six skin cancer diagnosis and evaluation planning scores. The dermatologists had significantly higher scores than the control group in 11 of the 14 diagnoses and evaluation planning categories.
The intervention group showed greater improvement than the control group across all six diagnostic categories (a gain of 13 percentage points vs. five, P<0.05) and in evaluation planning for malignant melanoma (a gain of 46 percentage points vs. 36, P<0.05) and squamous cell carcinoma (a gain of 42 percentage points vs. 21, P<0.01). The intervention group performed as well as the dermatologists on five of the six skin cancer diagnosis and evaluation planning scores with the exception of the diagnosis of basal cell carcinoma.
Some caution is required in applying the findings of this study to clinical practice. The sample of primary care residents was relatively small and lacked variation. The pre-test may have been more difficult than the post- test, as suggested by the higher scores of all three groups of subjects at the post test. Routine clinical practice is likely to differ from the test situation used in the study.
Girgis et al 1996Questionnaires were sent to randomly selected family physicians in one region in Australia to investigate their beliefs and practices in relation to skin cancer prevention, early detection and management.97 family physiciansFamily physicians were randomly selected from the regional telephone book.Ineligible participants were those who were unable to be contacted, were specialists or were retired.91% of family physicians (N=86) indicated that they thought skin examinations were very/extremely worthwhile in the early detection of melanoma and other skin cancers. The three issues in which they felt most confident were performing a surgical excision (72%), diagnosing a basal cell carcinoma (71%), and advising patients on signs of skin cancer (69%). A total of 65% (53) of family physicians considered that they currently detected 90 to 100% of their patients with melanoma. Family physicians indicated that the factors most likely to encourage them to offer screening were patients being more informed about its benefits, patients initiating the procedure having instructions about the signs to look for, having long consultation times and a reduced patient workload (59%; N=57), and having consistent information about who needs screening and how often (57%; N=55). The factors that were most likely to discourage family physicians from screening their patients included lack of time (32%; N=31), forgetting (26%; N=25), lack of financial incentive (20%; N=19), not being familiar with the patients’ screening history (14%; N=14) and inability to convince patients who refuse (13%; N=13).Compared with family physicians throughout Australia, the survey had significantly fewer family physicians aged less than 30 years, and a significantly higher proportion aged 40 to 49 years
Raasch et al, 2000AustraliaA randomised control trial to assess the value of an educational intervention based on audit and feedback to family physicians. Clinical performance of family physicians was judged by the ability to make a correct clinical diagnosis based on histology of the excised lesion and to provide adequate surgical treatment. The doctors’ individual skin cancer practices were compared within and between groups before and after the intervention. Data were recorded on 1) the proportion of all lesions correctly diagnosed 2) unrecorded clinical diagnosis 3) inadequate excisions and 4) certainty of diagnosis.41 Family physicians (21 in intervention group and 20 in the control group)Family physicians working three or more sessions per week in a primary-care situation, who were available for the whole of the proposed 9 months of the study--The intervention group doctors showed improved performance in providing clinical information on pathology requests and in adequate surgical excision of skin lesions. Diagnostic performance did not improve significantly but physicians’ certainty of diagnosis did. When a skin cancer was present (based on the histology of the lesion) the intervention group doctors, before receiving the intervention, had made a correct diagnosis in 72.2% (95% ci 65.8–78.6) of cases. After the intervention 77.1% (95% ci 68.7–85.5) of malignant lesions had been correctly diagnosed (P=.38). There also was no significant difference in sensitivity of diagnosis for malignant lesions between intervention and control group before or after the intervention. When a lesion was benign, the study group had made a correct diagnosis in 44.7% (95% ci 39.5–49.9) of cases before the intervention, compared with 28.5% (95% ci 23.8–33.2) in the control group. After the intervention 37.3% (95% ci 29.1–45.4) diagnoses were correct, compared with 22.4% (95% ci 11.7–33.1) in the control. The change in correct diagnoses before and after the intervention group was not statistically significant (P=0.144). A baseline comparison of patients who had skin lesions excised showed that the patients of intervention and control group doctors differed significantly in several ways.Factors such as patient characteristics that had not been controlled for may have limited the conclusions that could be drawn.
SIGN, Cutaneous melanoma: A National Clinical Guideline, 2003The guidelines recommended that: targeted education can enhance health professionals’ ability to diagnose melanoma (recommended best practice).

From: Appendix B, Evidence Tables

Cover of Referral Guidelines for Suspected Cancer in Adults and Children
Referral Guidelines for Suspected Cancer in Adults and Children [Internet].
NICE Clinical Guidelines, No. 27.
Clinical Governance Research and Development Unit (CGRDU), Department of Health Sciences, University of Leicester.
Copyright © 2005, National Collaborating Centre for Primary Care.

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