ER-negative breast cancer rates in Ghana matched those in US Black women

Estrogen receptor-negative breast tumours tend to appear earlier and behave more aggressively than ER-positive ones, and they are reported more frequently in women of West African ancestry. Whether that reflects genuinely higher rates, or is an artefact of comparing populations with very different age structures, has been an open question — largely because population-based studies in Africa with tumour pathology data are generally unavailable [s1].

A cross-sectional study published in JAMA Network Open on October 13 sets out to answer it with age-standardised rates on both sides of the comparison [s1].

How the rates were built

The Ghanaian estimates come from a population-based case-control study conducted in two metropolitan areas, Accra and Kumasi, using 2013 through 2015 data, covering women aged 18 to 74 [s1]. Incidence rates were recovered by applying sampling weights for controls calculated by district, by five-year age group, and by non-response rates, drawn from the 2010 census-based enumeration area listings [s1].

The US comparison used Surveillance, Epidemiology, and End Results data from 17 registries, for non-Hispanic Black and non-Hispanic white women aged 20 to 74 with breast cancer [s1]. Analyses were conducted between January 2020 and May 2025 [s1].

The samples were 1,071 women in Ghana, of whom 468 (51%) had ER-negative tumours; 18,321 US non-Hispanic Black women, of whom 5,117 (29%) were ER-negative; and 103,227 US non-Hispanic white women, of whom 15,040 (15%) were ER-negative [s1].

The result

ER-negative age-standardised incidence was 42.3 per 100,000 women (95% CI 38.7-46.3) in Ghana and 43.1 per 100,000 (42.0-44.3) in US non-Hispanic Black women [s1]. Both were higher than the 24.0 per 100,000 (23.6-24.4) in US non-Hispanic white women [s1].

ER-positive rates went the other way and diverged widely: 42.1 per 100,000 (38.4-46.1) in Ghana, 105.4 (103.6-107.3) in non-Hispanic Black women, and 128.5 (127.9-129.7) in non-Hispanic white women [s1].

The authors conclude that the similarity in ER-negative rates between Ghanaian and US non-Hispanic Black women, both exceeding those of US non-Hispanic white women, may suggest increased susceptibility requiring elucidation in these populations [s1].

Why the two halves of the result matter differently

The ER-negative finding disposes of the age-structure explanation. Age-standardisation removes the effect of a younger population, and the rates still match.

The ER-positive finding is doing different work. ER-positive incidence in Ghana is less than half that in US Black women and a third of that in US white women [s1]. ER-positive tumours are the ones most associated with reproductive and lifestyle exposures that differ between these settings, and they are also the ones most likely to be found by screening. A country with limited mammographic screening will detect fewer early ER-positive cancers — some of which would never have become symptomatic — which lowers the measured incidence.

So the ER-negative comparison is the one that supports an inference about susceptibility. The ER-positive comparison is at least as much a statement about detection systems as about biology, and the study does not attempt to separate those.

Limits of the reconstruction

The Ghanaian rates are not registry incidence rates. They are recovered from a case-control study by applying sampling weights derived from census enumeration listings [s1]. That is a legitimate method and it is the only route to population rates where a registry does not exist, but it inherits the assumptions of the weighting — chiefly that non-response was correctly characterised and that the two metropolitan areas studied represent the population being described.

The data cover 2013 through 2015 [s1], a decade before publication. And two metropolitan areas are not Ghana; urban and rural cancer patterns differ in most countries.

The word the authors use is "may suggest" [s1]. Nothing here identifies a susceptibility mechanism, genetic or environmental. It establishes that the rates are similar and that age structure does not explain them.

The context these numbers land in

Incidence is one end of the problem. An assessment published earlier in 2025 reviewed breast cancer management at Ghana's second-largest tertiary hospital against the WHO Global Breast Cancer Initiative's key performance indicators [s2]. Of 319 patients biopsied for suspicious breast lesions, 243 were diagnosed with breast cancer; median age was 49 and median symptom duration 24 weeks [s2].

Diagnosis was confirmed for all patients within 31 days of presentation, meeting the GBCI benchmark for timely diagnosis [s2]. But only 22 of 214 patients staged (10.3%) had early breast cancer at stage I or II, against a benchmark of 60% or more, and 45 of 243 (18.5%) with confirmed breast cancer completed recommended treatment without abandonment, against a benchmark above 80% [s2].

A population with elevated rates of an aggressive tumour subtype, arriving at stage III or IV, and dropping out of treatment, is a compound problem. The incidence study describes one component of it.

What to watch

Whether population-based cancer registration expands in Ghana, which would replace reconstructed rates with measured ones; whether the ER-negative similarity holds in other West African populations; and whether genetic or environmental work identifies what the susceptibility consists of.

This article describes epidemiological research and is informational only. It is not medical advice and does not recommend any screening decision.

Sources

• [s1] Breast Cancer Incidence Rates in Ghanaian and US Black Women From 2013 Through 2015, JAMA Network Open, 2025;8(10):e2537160, published online 2025-10-13.
• [s2] Assessing Breast Cancer Diagnosis and Management in Ghana per the Global Breast Cancer Initiative Key Performance Indicators, JCO Global Oncology, 2025;11:e2400653, published 2025-05-05.