Table 3. Relationship Between Histopathologic Pigmentation and AJCC Tumor Stage for 3,325 Primary Invasive Melanomas From 2,845 Patientsa.
| No. (%) of Melanomas | ||||
|---|---|---|---|---|
| Pigmented | Amelanotic | Amelanotic vs. Pigmented Melanoma | ||
| AJCC Tumor Stageb | (n=3,058) | (n=267) | Adjusted OR (95% CI)c | Ptrendd |
| T1a | 1,720 (97) | 54 (3) | 1 [Reference] | |
| T1b | 412 (92) | 36 (8) | 2.9 (1.8-4.6) | |
| T2a | 506 (91) | 53 (9) | 3.5 (2.3-5.4) | |
| T2b | 62 (79) | 16 (21) | 11.1 (5.8-21.2) | <.001 |
| T3a | 168 (82) | 38 (18) | 9.0 (5.6-14.5) | |
| T3b | 103 (89) | 13 (11) | 4.6 (2.3-9.2) | |
| T4a | 51 (64) | 29 (36) | 24.6 (13.6-44.4) | |
| T4b | 36 (56) | 28 (44) | 29.1 (15.5-54.9) | |
Abbreviations: AJCC, American Joint Committee on Cancer; OR, odds ratio; CI, confidence interval.
Invasive single melanomas and multiple melanomas (index and previous) with missing data for stage (n = 161) were excluded. We used marginal logistic regression with an independent correlation structure implemented in generalized estimating equations to account for the clustering of melanomas for multiple primary melanoma (MPM) patients.
T1a, Breslow thickness ≤1.0 mm and absence of ulceration or mitoses; T1b, Breslow thickness ≤ 1.0 mm and presence of ulceration or mitoses; T2a, Breslow thickness 1.01-2.0 mm without ulceration; T2b, Breslow thickness 1.01-2.0 mm with ulceration; T3a, Breslow thickness 2.01-4.0 mm without ulceration; T3b, Breslow thickness 2.01-4.0 mm with ulceration, T4a, Breslow thickness > 4.0 mm without ulceration; T4b, Breslow thickness > 4.0 mm with ulceration.
Adjusted for age (<50, 50-69, >70), sex, anatomic site (trunk, head/neck, upper extremities, lower extremities), study center, and lesion status (single primary melanoma, index MPM, or previous MPM).
Ptrend was calculated in the generalized estimating equation model including stage as an ordinal variable.