Background: Melanoma can remain clinically quiescent for decades before regional or distant recurrence appears. This protracted disease free interval challenges the concept of a "cure" for melanoma.
Methods: To understand this prolonged dormancy better, the authors retrospectively studied patients who developed recurrent melanoma 15 years or longer after their initial diagnosis ("ultra-late" recurrence). These cases were identified from 2766 melanoma diagnoses available in the Cancer Registry at the Massachusetts General Hospital (MGH). Histologic features of the primary lesion were also included when possible.
Results: Twenty cases were retrieved from the MGH database. There were equal numbers of women and men, although women were younger at the time of initial diagnosis (mean age of women: 29.8 years vs. 43.0 years for men). No patients had more than one primary cutaneous melanoma. The trunk was the most common primary site (35%), although there was no predominant anatomic localization. The average disease free interval was 17.3 years for women, 20.0 years for men, 18.1 years for patients with regional recurrence, and 19.0 years for patients with distant metastases. Distant recurrence was the most common type of recurrence (50% of women and 60% of men). The estimated probability of survival (5 years after recurrence) was 0.8 for regional disease and 0.2 for distant disease. With the available histologic records, it appears that almost all tumors were Clark Level III or IV with thicknesses ranging from 0.8-2.3 mm. In contrast to the published cases, this study did not find that women with lower extremity melanomas were at higher risk for developing ultra-late recurrence.
Conclusions: Ultra-late recurrence of melanoma, although uncommon, can occur in any patient without identifiable risk factors. Because many prognostically favorable melanomas (thin melanomas on extremities) can recur after prolonged disease free intervals, the possibility of delayed recurrence remains and must be kept in mind.