A deep look into thin melanomas: What’s new for the clinician and the impact on the patient

Abstract

Melanoma incidence and mortality are on the rise and although most new cases of melanoma are thin, a significant percentage of these patients still experience disease progression. The American Joint Committee on Cancer publishes staging criteria for melanoma, which were recently updated to the 8th edition. The most significant revision from the 7th edition affects the T1b classification, which now includes melanomas with a Breslow depth of 0.8 mm to 1.0 mm. The second major revision eliminates mitoses as a criterion to upstage a thin melanoma to T1b. Although mitotic figures have been established as an independent prognostic factor, they do not have a significant correlation with sentinel lymph node (SLN) biopsy positivity. SLN status remains the most important independent prognostic factor in thin melanomas. Nonetheless, the identification of patients who are at the highest risk for having a positive SLN test result remains difficult. Importantly, a positive SLN test result has high positive predictive value, but a negative one has very low negative predictive value. Since there is no proven survival benefit in performing an SLN biopsy in T1 disease, dermatologists need to have a personalized discussion with patients with thin melanomas to review expected risks and benefits before undertaking this procedure.

The Importance of Immunohistochemistry in the Evaluation of Tumor Depth of Primary Cutaneous Melanoma

“…The Breslow thickness is considered the “bedrock” for melanoma staging, and its precise measurement requires a complete excision [ 17 ], as other less-invasive techniques used for the diagnosis of malignant lesions, such as shave biopsy or exfoliative cytology did not provide reliable results [ 26 , 27 ]. Previous studies reported a worse prognosis in patients with tumoral thickness >0.75 mm [ 28 , 29 , 30 ], which led to the establishment of the 0.8 mm thickness as a cut-off value in the 8th edition of the AJCC staging manual [ 31 ]. Although thin melanomas (considered ≤1 mm) usually have a generally accepted good prognosis, the survival rate decreases with every 0.1 mm increase in the tumor thickness [ 32 ].…”

ASO Author Reflections: Impact of an Online Risk Calculator for Sentinel Node Positivity on Management of Patients with T1 and T2 Melanomas

“…These patients account for approximately 25% of melanoma deaths overall. 2 While sentinel lymph node (SLN) positivity is a predictor of worse prognosis in thin melanoma patients, the vast majority (94.4%) of cases are negative. 3 Predicting SLN positivity for thin melanoma patients remains difficult.…”

The benefit of early‐stage diagnosis: A registry‐based survey evaluating the quality of life in patients with melanoma

“… 25 Personal history of melanoma in situ is also a risk factor for developing future melanomas and other cancers. 26 , 27 Because heightened screening increases detection of thin melanomas, 17 , 28 , 29 investigation is needed to determine how earlier stage at diagnosis affects all aspects of patient outcome, including patient morbidity and QoL.…”