Timing of Clinical Detection and Biopsy in Invasive Melanoma and Breslow Depth: A Chart Review

Recent studies demonstrate the importance of prompt diagnosis of melanoma.^1,2 Diagnosis within 2 weeks from referral to dermatology is associated with thinner Breslow depth and greater survival. ¹ Based on this evidence, a 2-week rule for assessment of suspected melanoma was implemented across the United Kingdom. ¹ In locations such as ours with shortages of dermatologists, the wait for assessment of suspected melanoma can be longer than 2 weeks. ³ We sought to evaluate the relationship between wait time for melanoma assessment and Breslow depth at diagnosis (the most important marker of prognosis). ⁴ A secondary objective was to evaluate whether dermatologists detected melanoma at an earlier Breslow depth compared to other specialists.

We conducted a chart review of all incident cases (N = 1573) of invasive melanoma diagnosed at The Ottawa Hospital Cancer Centre (TOHCC) over 10 years (2006-2016). Exclusion of cases for whom Breslow depth was not available (ie, due to an unknown primary) yielded 1354 cases.

In terms of wait times, only 160 (11.8%) patients had information on both date of diagnosis and biopsy. From this restricted sample, most patients were biopsied within 1 month of detection of the lesion (n = 135), corresponding to an average Breslow depth of 1.97 mm. Of these patients, most (n = 125) were biopsied within 2 weeks (average Breslow depth 1.90 mm), and several were documented as having their melanomas detected and biopsied on the same day (n = 107, average Breslow depth of 1.78 mm). Last, patients who waited greater than a month from detection to biopsy (n = 25) had the highest average Breslow depth of 2.45 mm. Statistical testing was not performed on these results given the highly restricted sample of patients for whom these data are available, but a trend for increasing Breslow depth with increasing delays from melanoma detection to biopsy is suggested.

Information on who detected the melanoma was available for 943 patients (69.6%). A minority of cases were detected by dermatologists (n = 180, 19.1%, average Breslow depth 2.14 mm). The remaining 763 melanomas were detected by other health care workers, including other physicians, nurses, and allied health care workers such as massage therapists (average Breslow depth 2.59 mm).

Our results suggest that prompt biopsy of suspected melanoma is associated with reduced Breslow depth, consistent with previous studies.^1,2 Furthermore, this study suggests that melanomas are detected by dermatologists at an earlier stage of development, corresponding to thinner Breslow depths, compared to other specialists. These results must be interpreted in the context of several limitations, most notably the restricted sample of information that was available. Wait times were available for only 11.8% of patients. Most consult notes did not include who detected the melanoma, and the dates of referrals placed were not tracked. This identifies an important limitation of retrospective chart reviews and the need for comprehensive collection of pertinent clinical information in medical records. Ideally, the association of melanoma wait times and prognostic features, such as Breslow depth, would be examined in a prospective study that implements a strict referral to biopsy time frame, such as through a melanoma rapid access clinic.