Trend in relative survival in squamous cervical cancer by decade from 1983 to 2012: a period analysis

Abstract

Objective: Squamous cervical cancer (SCC), the predominant histological type, represents approximately 75-80% of all cervical cancers. Although the overall incidence of cervical cancer has declined worldwide, the data describing the changes in the incidence and long-term survival in SCC remain limited.

Methods: The data were extracted from Surveillance, Epidemiology, and End Results (SEER) registries for an evaluation of the changes in the incidence and survival associated with SCC during 1983-2012. In addition, the patients with SCC were stratified by age, race, and socioeconomic status (SES). Stata 12.0 software was used to perform the Cox regression and Spearman's rank correlation analyses.

Results: The overall incidence of SCC constantly declined from 7.3 to 5.6 to 4.3 per 100,000 people; the peak age of incidence was 55-69 years in the first decade, while the 40-54 age group served as another incidence peak in the last 2 decades. Median survival increased from 189 months to 231 months in the first 2 decades and was not reached in the third decade. The 10-year relative survival rates (RSRs) changed from 63.2% to 66.5% to 62.1% across the 3 decades. Additionally, the survival gaps narrowed from 13% to 8% between Whites and Blacks and from 5.4% to 3.5% between low- and medium-poverty groups in the 3 decades.

Conclusion: This study demonstrated a declining incidence over the 3 decades with an improvement in median survival. However, the relative survival associated with SCC did not improve in the last decade. Furthermore, the survival gaps between races and various SESs significantly narrowed over the 3 decades.

Keywords: incidence; period analysis; relative survival; squamous cervical cancer; tendency.

Figure 1

Summary incidences of patients diagnosed with SCC between 1983 and 2012 at the original 9 SEER sites. Notes: Incidence (A) and number (B) of SCC cases are showed by age group (total and ages 0–24, 25–39, 40–54, 55–69, and 70+ years) and calendar period. Incidence (C, D, E, F) of SCC cases are grouped by race and SES, respectively. Abbreviations: SCC, squamous cervical cancer; SEER, Surveillance, Epidemiology, and End Results; SES, socioeconomic status.

Figure 2

Trends in 10-year RSRs (A) and Kaplan–Meier survival analyses (B) for the patients with SCC at 18 SEER sites during 1983–1992 (orange), 1993–2002 (blue), and 2003–2012 (black) according to age group (total and ages 25–39, 40–54, 55–69, and 70+ years) and calendar period. Abbreviations: RSRs, relative survival rates; SCC, squamous cervical cancer; SEER, Surveillance, Epidemiology, and End Results.

Figure 3

The 5-year and 10-year RSRs according to race (A) and SES/county-level poverty rates (B), and Kaplan–Meier survival analyses according to race (C) including White (orange), Black (blue), and others (black), and SES/county-level poverty rates (D) in low-poverty (orange), medium-poverty (blue), and high-poverty (black) for patients with SCC at 18 SEER sites from 1983 to 2012. Abbreviations: RSRs, relative survival rates; SCC, squamous cervical cancer; SEER, Surveillance, Epidemiology, and End Results.