Morton D L, Davtyan D G, Wanek L A, Foshag L J, Cochran A J
John Wayne Cancer Institute, Saint John's Hospital and Health Center, Santa Monica, CA 90404.
Cancer. 1993 Jun 1;71(11):3737-43. doi: 10.1002/1097-0142(19930601)71:11<3737::aid-cncr2820711143>3.0.co;2-7.
The American Joint Committee on Cancer (AJCC) uses both Breslow thickness and Clark level in its staging system for malignant melanoma. Stage I corresponds to Breslow thicknesses less than 1.5 mm and Clark levels II and III. Stage II corresponds to Breslow thicknesses of at least 1.5 mm and Clark levels IV and V. However, most investigators have found Clark level to be of no prognostic significance once Breslow thickness has been taken into consideration by multivariate analysis.
The authors examined the prognostic significance of Clark level by studying patients in the large database of the John Wayne Cancer Institute. Among 5575 patients with melanoma seen during the past 20 years, complete data on microstaging by both Clark and Breslow methods were available for 3323 patients. The 5-year survival rates were as follows: Clark II, 95%; III, 81%; IV, 68%; V, 47%. The Breslow thicknesses were as follows: < 0.75 mm, 95%; 0.75-1.49 mm, 85%; 1.5-3.99 mm, 66%; > or = 4.0 mm, 46%.
By univariate analysis, both Clark level and Breslow thickness were highly significant prognostic indicators (P < 0.0001). By multivariate analysis, Breslow thickness remained significant (P < 0.0001). However, even when Breslow thickness was included in the model, Clark level also remained highly significant (P < 0.0015).
Decisions regarding therapy for patients with clinical Stage I melanoma should consider both Clark level and Breslow thickness of the primary lesion. When there is a discordance between the two methods of microstaging, the AJCC stage should be amended to reflect the least favorable of the two prognostic indicators.
美国癌症联合委员会（AJCC）在其恶性黑色素瘤分期系统中同时使用 Breslow 厚度和 Clark 分级。I 期对应 Breslow 厚度小于 1.5 mm 以及 Clark 分级 II 级和 III 级。II 期对应 Breslow 厚度至少为 1.5 mm 以及 Clark 分级 IV 级和 V 级。然而，大多数研究者发现，经多变量分析考虑 Breslow 厚度后，Clark 分级并无预后意义。
作者通过研究约翰韦恩癌症研究所的大型数据库中的患者，检验 Clark 分级的预后意义。在过去 20 年中诊治的 5575 例黑色素瘤患者中，3323 例患者同时有 Clark 和 Breslow 两种微分期方法的完整数据。5 年生存率如下：Clark II 级，95%；III 级，81%；IV 级，68%；V 级，47%。Breslow 厚度如下：<0.75 mm，95%；0.75 - 1.49 mm，85%；1.5 - 3.99 mm，66%；≥4.0 mm，46%。
单变量分析显示，Clark 分级和 Breslow 厚度均为高度显著的预后指标（P < 0.0001）。多变量分析中，Breslow 厚度仍具有显著性（P < 0.0001）。然而，即便模型中纳入了 Breslow 厚度，Clark 分级也仍具有高度显著性（P < 0.0015）。
对于临床 I 期黑色素瘤患者的治疗决策应同时考虑原发灶的 Clark 分级和 Breslow 厚度。当两种微分期方法结果不一致时，AJCC 分期应进行修正，以反映两个预后指标中最不利的情况。
