Impact of the 2009 (7th Edition) AJCC Melanoma Staging System in the Classification of Thin Cutaneous Melanomas

Table 1

Classification of patients with T1 invasive melanoma according to the 2001 and 2009 AJCC staging and classification system (𝑁=106).

Melanoma categories			2001 AJCC, 6th edition		2009 AJCC, 7th edition		Reclassified T1 melanomas according to 2009 AJCC staging	Median BT in mm (range)
Clark level	Mitosis	Ulceration	T1a	T1b	T1a	T1b
II	−	−	31	0	31	0	No	0.30^† (0.12–1.0)
II	+	−	3	0	0	3	Yes	0.70 (0.44–0.80)
II	−	+	0	1	0	1	No	0.64 (0.64–0.64)
II	+	+	0	0	0	0	No	—
III	−	−	14	0	14	0	No	0.55 (0.38–0.85)
III	+	−	12	0	0	12	Yes	0.79 (0.35–1.0)
III	−	+	0	0	0	0	No	—
III	+	+	0	3	0	3	No	0.90 (0.65–0.94)
IV	−	−	0	16	16	0	Yes	0.55 (0.32–0.98)
IV*	+	−	0	26	0	26	No	0.70 (0.44–0.98)
IV	−	+	0	0	0	0	No	—
IV	+	+	0	0	0	0	No	—
Total			60	46	61	45	31	0.60 (0.12–1.0)

Reclassified T1a and T1b cohorts are listed in bold. Median BT of 0.30 mm was significantly lower compared to BT in other categories^†: (𝑃<0.01). Mitosis “+”: 1 or more dermal tumor mitosis/mm²; mitosis “−”: <1 or 0 dermal tumor mitosis/mm²; ulceration “+”: histological absence of epidermis with accompanying inflammatory crust; ulceration “−”: histologically intact epidermis; BT: Breslow thickness; *category with positive sentinel lymph node biopsy (SLNB).