The Relationship Between Melanoma Thickness and Time to Diagnosis in a Large Population-Based Study

OBJECTIVE: To examine the relationship between melanoma thickness and reported time from first recognition and from first physician contact to the diagnosis of invasive melanoma. DESIGN: Telephone survey of patients recently diagnosed as having melanoma, combined with relevant pathological data (including melanoma thickness and morphologic structure) from the population-based Queensland Cancer Registry. A test-retest study (n = 176) was also conducted. SETTING: Population-based study in Queensland. PARTICIPANTS: Residents of Queensland (n = 3772) who had been diagnosed as having invasive melanoma between January 1, 2000, and December 31, 2003. MAIN OUTCOME MEASURES: Prepresentation time (time between first noticing a suspicious spot and the first physician visit), postpresentation time (time between the first physician visit and diagnosis), and total time to diagnosis (time from initial detection of the melanoma to diagnosis). RESULTS: With 1 exception, we found no significant association between melanoma thickness and reported time to diagnosis for all melanomas combined, superficial spreading melanomas, or nodular melanomas. The exception was a positive association between melanoma thickness and postpresentation delay of physician-detected nodular melanomas. The reliability study gave intraclass correlation coefficients of 0.85 to 0.90 for the measures of intervals. CONCLUSIONS: This large study demonstrates no clear relationship between the melanoma thickness when diagnosed and the time from first recognition of changes or from first physician examination to diagnosis. This may be because of varying biological characteristics of melanomas, as well as methodological limitations of retrospective studies when trying to measure this complex association.