Identify patterns in cervical cancer incidence in Ontario according to neighborhood sociodemographic characteristics over time and by morphologic type.
Incident cases of cervical cancer diagnosed from 1991 to 2009 were obtained from the Ontario Cancer Registry. Population data and data on neighborhood sociodemographic characteristics were obtained from the Canadian Census. Age-standardized incidence rates (ASIR) and rate ratios (RRs) with 95% confidence intervals (CIs) were calculated for each sociodemographic characteristic, stratified by morphologic type (squamous cell carcinoma and adenocarcinoma) and time period of diagnosis.
Incidence was 51% higher in the poorest neighborhoods compared with the richest (RR, 1.51; 95% CI, 1.42–1.61) and 7% higher in rural areas compared with urban (RR, 1.07; 95% CI, 1.01–1.13). Incidence of squamous cell carcinoma was significantly higher in the poorest neighborhoods compared with the richest (RR, 1.74; 95% CI, 1.61–1.88), a trend observed for all time periods, and in rural areas compared with urban (RR, 1.10; 95% CI, 1.02–1.18). For adenocarcinoma, ASIRs in the earlier time period (1991–1998) were higher in the poorest neighborhoods compared with richest (RR, 1.26; 95% CI, 1.01–1.57), whereas for the more recent time period (1999–2009), ASIRs were lower for women living in the poorest neighborhoods compared with the richest (RR, 0.82; 95% CI, 0.68–0.99).
This study identified significantly higher incidence of cervical cancer in low-income neighborhoods in Ontario. The association was especially pronounced for squamous cell carcinoma and varied by time period for adenocarcinoma. Improvements to screening and prevention efforts against oncogenic human papillomavirus strains would increase the detection of cervical cancer, adenocarcinoma especially, and may further reduce cervical cancer incidence.
*Cancer Care Ontario, Toronto; †Division of Gynecologic Oncology, Juravinski Cancer Center, Hamilton; and ‡Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
Address correspondence and reprint requests to Loraine D. Marrett, PhD, Cancer Care Ontario, 505 University Ave, 14th Floor, Toronto, Ontario, Canada M5G 1X3. E-mail: Loraine.Marrett@cancercare.on.ca.
The authors declare no conflicts of interest.
Received April 17, 2014
Received in revised form June 15, 2014
Accepted June 15, 2014