Cancer Res Treat.  2018 Jan;50(1):164-174. 10.4143/crt.2017.072.

Epidemiology of Intracranial Metastases in Korea: A National Cohort Investigation

• Kim T
• Song C
• Han JH
• Kim IA
• Kim YJ
• Kim SH
• Kim JH
• Kim CY

• KMID: 2403486
• DOI: http://doi.org/10.4143/crt.2017.072

Abstract

PURPOSE
To investigate the epidemiologic features of intracranial metastases (ICMET) in Korea, we performed a cohort study using the National Health Insurance Service-National Sample Cohort database, which comprised healthcare usage information of approximately 1 million Korean individuals over 12 years.
MATERIALS AND METHODS
We enrolled 998,602 subjects, after excluding 18,218 subjects diagnosed with any cancer during the washout period (2002-2004). The observation period was 9 years (2005-2013; 8,725,438 person-years). The initial diagnosis date of ICMET and the primary cancer was recorded. The incidence was determined based on the number of incident cases and observation size, whereas survival was estimated using death statistics from the database.
RESULTS
Through observation period, a total 776 subjects developed ICMET. The age-standardized incidence of ICMET was 8.2 per 100,000 person-years. The mean interval between the initial diagnosis date of the primary cancer and ICMET was 13.1 months. Patients with ICMET had shorter survival than those without ICMET (30.9 months vs. 81.4 months, p < 0.001). The ICMET incidence among the cancer patients was 5.0 per 1,000 person-years; it was highest in lung cancer cases, followed by breast and liver cancer cases. Moreover, ICMET from lung cancer was the most common metastasis type, followed by ICMET from liver and breast cancer.
CONCLUSION
The incidence of ICMET was 8.2 per 100,000 person-years among the Korean population and 5.0 per 1,000 person-years among cancer patients. Most of the ICMET cases arose from lung cancer. ICMET also critically influenced survival in cancer patients.

Keyword

Epidemiology; Intracranial metastases; Cohort; National; Korea; Incidence

MeSH Terms

Breast
Breast Neoplasms
Cohort Studies*
Delivery of Health Care
Diagnosis
Epidemiology*
Humans
Incidence
Korea*
Liver
Liver Neoplasms
Lung Neoplasms
National Health Programs
Neoplasm Metastasis*

Figure

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  Fig. 1. Heatmap of the population structures. The proportion of each age group is presented as a percentage. The population structure of this cohort is very similar to that generated by the Korean census 2005 data. However, the World Health Organization (WHO) 2000-2025 population structure is markedly different from both these population structures.

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  Fig. 2. Bar graph indicating the cancer incidence by age group. In general, older subjects show higher cancer incidence. The peak incidence is 2,052 per 100,000 person-years in subjects aged 70-79 years.

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  Fig. 3. Survival curves of lung (A), breast (B), and liver (C) cancer patients. Patients with intracranial metastases (ICMET) showed poorer survival (p < 0.001). The shading indicates the 95% confidence interval.

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  Fig. 4. Survival curve shows cumulative incidence of intracranial metastases (ICMET) from diagnosis of lung cancer. Initial steep slope indicates high rate of simultaneous diagnosis with primary cancer.

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  Fig. 5. (A) Bar graph shows detailed statistics of incidence by sex and age groups. (B) Survival function by sex and age group. Younger age group represents age < 60 patients. ICMET, intracranial metastases; Y/M, younger male; Y/F, younger female; O/M, older male; O/F, older female.

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  Fig. 6. Line graphs shows chronological change of statistics regarding intracranial metastases (ICMET) from lung cancer. Incidence shows incremental trend over years, while mean interval does descending.

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