Stage at diagnosis of breast cancer in sub-Saharan Africa: a systematic review and meta-analysis

Abstract

Background: The incidence of breast cancer in sub-Saharan Africa is relatively low, but as survival from the disease in the region is poor, mortality rates are as high as in high-income countries. Stage at diagnosis is a major contributing factor to poor survival from breast cancer. We aimed to do a systematic review and meta-analysis on stage at diagnosis of breast cancer in sub-Saharan Africa to examine trends over time, and investigate sources of variations across the region.

Methods: We searched MEDLINE, Embase, Web of Knowledge, and Africa-Wide Information to identify studies on breast cancer stage at diagnosis in sub-Saharan African women published before Jan 1, 2014, and in any language. Random-effects meta-analyses were done to investigate between-study heterogeneity in percentage of late-stage breast cancer (stage III/IV), and meta-regression analyses to identify potential sources of variation. Percentages of women with late-stage breast cancer at diagnosis in sub-Saharan Africa were compared with similar estimates for black and white women in the USA from the Surveillance, Epidemiology, and End Results database.

Findings: 83 studies were included, which consisted of 26 788 women from 17 sub-Saharan African countries. There was wide between-study heterogeneity in the percentage of late-stage disease at diagnosis (median 74·7%, range 30·3-100%, I²=93·3%, p<0·0001). The percentage of patients with late-stage disease at diagnosis did not vary by region in black women, but was lower in non-black women from southern Africa than in black women in any region (absolute difference [AD] from black women in western Africa [reference group] -18·1%, 95% CI -28·2 to -8·0), and higher for populations from mixed (urban and rural) settings rather than urban settings (13·2%, 5·7 to 20·7, in analyses restricted to black women). The percentage of patients with late-stage disease at diagnosis in black Africans decreased over time (-10·5%, -19·3 to -1·6; for 2000 or later vs 1980 or before), but it was still higher around 2010 than it was in white and black women in the USA 40 years previously.

Interpretation: Strategies for early diagnosis of breast cancer should be regarded as a major priority by cancer control programmes in sub-Saharan Africa.

Funding: None.

Figure 1

Study selection

Figure 2. Study-specific breast cancer stage at diagnosis

Study-specific distribution of stages I, II, III, and IV cancers. Percentage of T3/T4 cancers was used as a proxy for percentage of stage III/IV cancers in four studies.^– Percentage with metastases (M1) was given in three studies^,, and was used as percentage of stage IV. Race as defined in table 1 and in the appendix (p 14). Study-specific references given in the appendix (p 14). B=black. C=coloured. I=Indian. NPL=non-pregnant or non-lactating women. PL=pregnant or lactating women. W=white.

Figure 3. Study-specific breast cancer stage at diagnosis

Study-specific percentage of late-stage disease (III/IV) ranked by increasing magnitude. Percentage of T3/T4 cancers was used as a proxy for percentage of stage III/IV cancers in four studies.^– Race as defined in table 1 and in the appendix (p 14). Study-specific references given in the appendix (p 14). B=black. C=coloured. DRC=Democratic Republic of the Congo. I=Indian. NPL=non-pregnant or non-lactating women. PL=pregnant or lactating women. W=white.

Figure 4. Study-specific percentage of late-stage breast cancer at diagnosis, by region of sub-Saharan Africa

B=black African. C=coloured. I=Indian. NPL=non-pregnant or non-lactating women. PL=pregnant or lactating women. W=white. Study-specific references given in the appendix (p 14). *Weights are from random effects analyses.

Figure 5. Trends in stage of breast cancer at diagnosis in sub-Saharan Africa in 1960–2011, and in the USA in 1973–2002 and 1988–2011

The US estimates represent percentage of patients with breast cancer with regional or distant disease (as a proxy for stages III/IV) out of all patients with known stage in the Surveillance Epidemiology End Results (SEER) database (see Methods); the SEER summary staging classification was used for both time periods: 1973–2002 (based on 365 695 white women and 31 781 black women with breast cancer in the USA) and 1998–2011 (based on 780 137 white women and 96 526 black women with breast cancer in the USA). The discontinuity between the two time series was due to a change in staging classification. The sub-Saharan Africa estimates correspond to percentage of patients with stage III/IV breast cancer at diagnosis; the size of the point estimate symbols are proportional to the size of the study.