Background

Melanoma of unknown primary (MUP) is incompletely described on a population level.

Objective

We sought to characterize stage IV MUP in a population-based cancer registry.

Methods

We developed a novel search algorithm to identify cases of stage IV MUP in the Surveillance, Epidemiology, and End Results 18 registries from 1973 to 2014. Cases of stage IV melanoma of known primary (MKP) served as a comparison group. Age-standardized incidence rates, demographic characteristics, adjusted disease-specific survival, and Cox proportional hazard models were calculated for MUP and MKP.

Results

A total of 322 stage IV MUP cases and 12,796 stage IV MKP cases were identified in Surveillance, Epidemiology, and End Results 18 registries from 1973 to 2014. The incidence of stage IV MUP is increasing, particularly for patients younger than 30 years of age. In multivariate analyses, age older than 50 and a lack of surgical treatment were negative prognostic factors for stage IV MUP. Relative survival, but not 5-year adjusted disease-specific survival, was higher for stage IV MUP than for MKP.

Limitations

Limitations include the retrospective study design and possible misclassification of MUP.

Conclusions

The incidence of stage IV MUP is increasing, and stage IV MUP shares similar prognostic factors with stage IV MKP, including age and surgical treatment.

中文翻译：

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原发性未知的IV期黑色素瘤：1973年至2014年在美国进行的一项基于人群的研究

背景

原发性黑色素瘤（MUP）在人群水平上不完整描述。

客观的

我们试图在基于人群的癌症登记系统中表征IV期MUP。

方法

我们开发了一种新颖的搜索算法，以识别1973年至2014年间的监测，流行病学和最终结果18注册表中的IV期MUP病例。将已知原发性（MKP）的IV期黑色素瘤病例作为比较组。计算了MUP和MKP的年龄标准化发病率，人口统计学特征，调整的疾病特异性生存率和Cox比例风险模型。

结果

1973年至2014年间，在监视，流行病学和最终结果18登记处总共鉴定出322例IV期MUP病例和12,796例IV期MKP病例。IV期MUP的发病率正在增加，尤其是对于30岁以下的患者。在多因素分析中，年龄大于50岁且缺乏手术治疗是IV期MUP的不良预后因素。IV期MUP的相对生存率较高，但5年调整后的疾病特异性生存率则高于MKP。

局限性

局限性包括回顾性研究设计和可能的MUP分类错误。

结论

IV期MUP的发生率正在增加，IV期MUP与IV期MKP具有相似的预后因素，包括年龄和手术治疗。