Melanoma underreporting: why does it happen, how big is the problem, and how do we fix it?

Melanoma incidence trends from population-based cancer surveillance programs, such as the National Cancer Institute-funded Surveillance, Epidemiology and End Results (SEER) program, are central to evaluating primary prevention and screening programs1,2, and raising awareness of increasing trends in subgroups that should be targeted for primary and secondary prevention3. However, it is widely recognized that trends in melanoma incidence are affected by reporting and surveillance issues. For example, previous reports have detailed both under-reporting4 and delayed (up to 7-10 years) reporting5 of melanomas to cancer registries. Inaccurate surveillance will mislead melanoma control efforts and impact our ability to respond in a timely fashion with public health initiatives. Melanoma, like other cancers, appears on the Confidential Morbidity Report (CMR), and is mandated by law in all 50 states to be reported by diagnosing physicians to central registries. Poor reporting can occur for cancers of any site5, but the potential of reporting inconsistencies and corresponding bias in trend estimation is especially high for melanoma, and likely to worsen with the increasing decentralization of melanoma diagnosis and outpatient treatment away from hospital settings. In some hospitals, cancers are now identified automatically via electronic reporting systems. Outside of those systems, diagnosing physicians must ensure that their patients' melanomas are being reported to central cancer registries by confirming their reporting arrangements or through direct contact with the regional cancer registry. In this review, we provide an overview of the most likely reasons for melanoma under-reporting, describe the seriousness of the problem using dermatologist survey data recently collected by two SEER cancer registries, and provide information for clinicians on how to get involved in the solution. Why are melanomas more likely to be under-reported than other cancers? Melanoma diagnoses are more often occurring in an outpatient setting, which makes these cancers more likely than others to be underreported to cancer registries. With the adoption of narrower excision margins for melanoma6 and the potential use of Mohs micrographic surgery for superficial melanoma, greater numbers of thin cutaneous melanomas are likely to be diagnosed and treated in the outpatient setting7 where automated surveillance systems do not always exist. Using these records to cross-check the already-reported diagnoses is also an essential component of ensuring completeness in population-based reporting. All central cancer registries are skilled at removing duplicate records by consolidating reports of the same cancer from multiple sources. However, reports from hospitals and pathology laboratories do not represent all melanomas being diagnosed in recent years. Figure 1 shows the typical distribution of sources of reporting for melanomas for three years in Los Angeles County. About 80% of melanoma reports come from ‘routine reporting’ (reports obtained from hospitals and clinics), while 20% come solely from the Registry's additional efforts to obtain information on melanoma diagnosis from a physician who should have reported the case. These occur when we receive a report implying that a melanoma was followed-up (e.g. a report of ‘clear margins’ from a pathology laboratory), but we cannot find the original case in our records because it was never reported in the first place. To our knowledge, these reports are not routinely collected by Registries (other than Los Angeles and the San Francisco/Greater Bay Area). The pathology resolution process provides some indication of the minimum number of melanomas being missed if we relied on ‘routine’ reporting only. In Los Angeles County about 10% of melanoma incident cases annually are found only from pathology laboratory sources. Figure 1 Sources of melanoma case reports received by the Los Angeles Cancer Surveillance Program, 2004-2006 These data suggest that less than one percent of all melanomas reported to the Registry come from physician reporting. Data from most population-based registries show a similar ‘passive’ system of reporting, with comparable proportions of melanomas being reported by physicians. These low proportions of reporting underscore the potential for an unacceptably high percentage of melanomas to be missed in population-representative data.