Trends in Malignant Lacrimal Gland Tumors And Lacrimal Sac Tumors

This study was supported by the Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan. The authors have no proprietary or commercial interest in any of the materials discussed in this article.

However, diagnosis is often delayed because the symptoms, such as epiphora, a palpable mass, are often confused with those of a relatively benign etiology. Thus far, few studies have examined the incidence trends of lacrimal gland and lacrimal sac malignancies in the United States. In this study, the incidence and survival trends of patients with primary malignant tumors of the lacrimal gland and lacrimal sac were examined in a large population by using data from the population-based US National Cancer Institute's SEER cancer registry.

Methods
A population-based cohort analysis of patients who had received a diagnosis of primary malignant tumors in the lacrimal gland and lacrimal sac was performed using the case-listing session of the Next, we used site-specific data items (SSDIs) to discriminate between the lacrimal sac and lacrimal gland. The following primary data were extracted from the database for analysis: age at diagnosis, sex, race, socioeconomic status, marital status, tumor extent, and tumor size from both extent of disease and collaborative stage coding methods, tumor grade, tumor TNM stage, treatment methods, and 5-year survival in months. Welldifferentiated and moderately differentiated histological subtypes were grouped as low-grade tumors, whereas poorly differentiated and undifferentiated histological subtypes were grouped as highgrade tumors. Lymphomas and melanomas were excluded.
The trend of the incidence rate examined using the joinpoint analysis was calculated per 100,000 person-years and age adjusted to the 2000 US standard population (single ages-census P25-1130); confidence intervals were set as 95% for rates and trends.
Percentage changes were calculated using one year for each endpoint. APCs were calculated using the weighted least-squares method. APCs were calculated on the basis of the entire study duration. Because data were extracted from a public, identified database, this study did not require approval from an institutional review board. Statistical analyses were performed using SPSS (version 20, SPSS Inc, Chicago, IL, USA). Because data was extracted from a public, deidentified database, this study did not require an institutional review board approval.

Lacrimal gland malignancy
In total, 114 patients with lacrimal gland malignancies were included in the study. Table 1  .041), whereas no significant difference was observed in the male patients with different socioeconomic status.

Discussion
The overall incidence rate of lacrimal gland malignancies exhibited a significant decreasing trend from 2009 through 2015 in white patients. Among the female patients, the white patients had a significantly lower incidence rate than did the nonwhite patients.
The patients with a lacrimal gland malignancy size of <2.5 cm had a significantly higher 5-year survival rate than did those with a tumor size of >2.5 cm. Regarding lacrimal sac malignancies, the female patients with low socioeconomic status exhibited a significantly higher incidence rate than did those with high socioeconomic status.
To our knowledge, our study is one of the few studies to describe the incidence trends of malignancies of the lacrimal gland and lacrimal sac in a large number of patients. SEER provides diverse validated databases with appropriate quality control.
Besides, SEER database allows study of rare malignancies with great statistical power. We combined ICD codes and SSDIs to discriminate between malignancies of the lacrimal sac and lacrimal gland; however, other studies have overlooked differences in their anatomical locations and have included both types of malignancies by using the same code C69.5.
Two studies analyzing the epidemiology of primary lacrimal gland malignancies based on the population-based database of the US National Cancer Institute's SEER Program have been published. 5 This epidemiological data regarding patient demographics improves our knowledge of predisposed populations for these diagnoses.

Conclusions
Lacrimal gland and lacrimal sac malignancies have been decreasing overall in recent years in the USA. Our study revealed that the incidence of the aforementioned malignancies vary with sex, race, and socioeconomic status. The trend of lacrimal gland malignancies has decreased significantly over the years in the white patients. This analysis of lacrimal gland and lacrimal sac malignancy trend improves our knowledge of predisposed populations during diagnosis.

Ethics approval and consent to participate
Because data was extracted from a public, deidentified database, this study did not require an institutional review board approval.