The impact of a negative sentinel lymph node biopsy on recurrence and survival after recurrence in melanoma

The authors reviewed the patterns of recurrence and survival after negative sentinel lymph node biopsy for melanoma.

The increasing incidence and prevalence of melanoma are in stark contrast to the overall decrease in the incidence rates of other cancers such as lung, prostate, breast, and colorectal cancer. Despite the increase in new cases, the percentage of patients with melanoma who have survived for 5 years has steadily increased.

The strongest predictor of melanoma recurrence is the status of the sentinel lymph node (the primary lymph node to which the cancer will spread). Therefore, sentinel lymph node biopsy (study of the lymph node tissue under a microscope) has become the standard of care for those with lesions greater than 1 mm.

The aim of this study was to evaluate the incidences of overall recurrence and of survival during long-term follow-up after a negative sentinel lymph node biopsy result.

515 patients who underwent a wide local excision (surgical removal of a small area of diseased tissue) with a negative sentinel lymph node biopsy were included in the analysis. The average follow up was 61 months. The average Breslow thickness (measuring how deeply the primary tumor has penetrated the skin) was 1.4 mm with 16.5% of patients having lesions that exhibited ulceration (discontinuity or break in the membrane).

16% of patients experienced recurrence after an average of 23 months after diagnosis. 4% of patients experienced a recurrence in the sampled lymph node basin (group of lymph nodes), implying a false-negative rate of 4%.  The initial site of recurrence was local (in the same place as the original tumor or very close by) for 22.9% of patients at an average of 14 months after diagnosis. 14.5% of patients had initial recurrence that was in-transit (growth at least 2 cm from the initial tumor but has not yet reached lymph nodes) at an average of 23 months after diagnosis. Recurrence was deemed to be regional (occurring in lymph nodes and tissue surrounding the initial tumor) for 25.3% of patients after an average of 14 months and distant for 31.3% of patients after an average of 30 months.

Increasing age was associated with a 5% increased risk of recurrence. Increasing Breslow thickness was associated with a 16% increased risk of recurrence. Ulceration was associated with almost 2.73 times the risk of recurrence while lesions in the head and neck region were associated with three times the risk.

Of those with regional recurrence, 66.7% underwent complete lymph node dissection, with 71.4% of these patients having additional lymph nodes testing positive for melanoma.  The presence of ulceration was found significantly more often in negative sentinel lymph node patients experiencing recurrence (32.5%) compared to those who did not experience recurrence (13.5%).

Of the 48 patients who experienced recurrence after a negative sentinel lymph node biopsy, 48.2% of patients died at an average of 15.5 months after recurrence. Those with a negative sentinel lymph node biopsy who experienced recurrence had a significantly reduced 5-year survival probability (68%) compared to those who did not experience a recurrence (98%). 42.1% of those with a local recurrence died during the study, 50% of those with an in-transit recurrence, 52.4% of those with a regional recurrence and 50% of those with a distant recurrence.

The authors stated that the rate of recurrence was similar to previous studies, with sentinel lymph node biopsy being associated with a false-negative rate of 4%.