Incidence and survival rates of ovarian cancer in low-income women in Sudan

Abstract

Ovarian cancer is the second most common gynecological cancer worldwide. Little is known about the disease in Sudan. The objective of the present study was to evaluate the incidence rate, age and stage at diagnosis, and median survival time of patients presenting at the National Cancer Institute-University of Gezira (NCI-UG), Sudan. Data were collected in a prospective study of women with ovarian cancer over a period of eleven years of follow-up (between 2000 and 2011). Descriptive statistics were used to summarize the distribution of the demographics of the sample. The direct method was used to compute the age-standardized rate (ASR) using data from the 1966 and 2000 World Standard Populations (WSPs). The Kaplan-Meier method was used to estimate survival functions and the median survival time. Log-rank tests were used to statistically compare between the survival functions. There were steady increases in ovarian cancer incidence rates between 2000 and 2009, with a slight decline noted in 2010 and 2011. The patients' age range was 9-90. The age-specific incidence rate increased greatly in women aged 55 years or older. The majority of the patients had stage III or IV disease. The annual ASR using WSPs 1966 and 2000 as standard populations were 3.3 and 3.7 per 100,000 women, respectively. The median survival time was 31 months (95% confidence interval, 19-43). The 5-year cumulative survival rate was 38%. In Sudan, ovarian cancer affects postmenopausal women, akin to what is reported in the developed world with high incidence rates. Presenting with advanced stage disease is the predominant factor that results in a short survival time for women.

Keywords: Africa; Gezira State; Sudan; age-standardized rate; ovarian cancer; papillary serrous cystadenocarcinoma; survival.

Figure 1.

Histological distribution of ovarian cancer.

Figure 2.

Annual incidence rates of ovarian cancer in Al Gezira State, Sudan, between the years 2000 and 2011.

Figure 3.

Rate of ovarian cancer between 2000 and 2011 using the 2000 WSP (dashed line), 1966 WSP (dotted line) and 2008 WSP (solid line) Sudan population. The x and y-axes show the year and age-standardized incidence rates of ovarian cancer per 100,000 population, respectively. WSP, World Standard Population.

Figure 4.

Age-specific rates of ovarian cancer in women in the Al Gezira State, Sudan, between the years 2000 and 2011.

Figure 5.

Kaplan-Meier plots showing the survival curves (A) according to the cancer stage (blue, stage 0 and I; green, stage II; orange, stage III; and black, stage IV) and (B) according to the location of the patient (rural area, continuous line; urban area, dashed line).