Regional differences in chemotherapy treatment for breast cancer may affect survival
The proportion of women with early breast cancer who receive chemotherapy varies significantly across different regions of Sweden. A study from Karolinska Institutet, published in the journal Breast Cancer Research, shows that these differences may affect survival among women aged 65 and over.
The study includes just over 62,000 breast cancer patients diagnosed between 2007 and 2023, with data retrieved from the Swedish National Quality Registry for Breast Cancer (NKBC).
The researchers investigated how often chemotherapy was used in different healthcare regions and whether these differences were associated with patients’ prognosis.
Clear differences despite national guidelines
In total, 28 percent of breast cancer patients received chemotherapy, but its use varied significantly across the country, from 23 percent in the western healthcare region to 34.7 percent in the Stockholm-Gotland healthcare region.
“We observed clear regional differences in the use of chemotherapy, despite the fact that breast cancer care is based on the same national guidelines,” says Johan Hartman, professor at the Department of Oncology-Pathology at Karolinska Institutet and senior consultant at Karolinska University Hospital.
The differences in treatment did not appear to affect survival among women younger than 65. For older women, however, the researchers observed a different pattern. Among women aged 65 or over, the ten-year mortality rate was 27.9 percent in the Stockholm-Gotland healthcare region and 35.8 percent in the western healthcare region, a difference of 7.9 percentage points.
More is needed to ensure equal healthcare
Even after taking differences in the biological characteristics of the tumours and socio-economic factors into account, regional differences in prognosis remained. Healthcare regions with lower use of chemotherapy had higher mortality rates. The researchers believe that local guidelines and treatment traditions may provide possible explanations for these differences.
“Our results show that common national guidelines are not always sufficient to ensure equal care. Particularly among patients over the age of 65, we see signs that more patients could have received more active treatment – and possibly had a better prognosis – if care had been more consistent across the country,” says Johan Hartman.
The study was carried out in collaboration between researchers at Karolinska Institutet, Karolinska University Hospital, the University of Gothenburg, Umeå University and Örebro University.
The research was funded, among others, by the Swedish Breast Cancer Association, Karolinska Institutet and the Swedish Cancer Society. Several of the authors report relationships with pharmaceutical companies, see the scientific article for more details.
Publication
”Variation in chemotherapy use across healthcare regions in Sweden and its impact on prognosis in women with HR+/HER2- early breast cancer”, Balazs Acs, Xingrong Liu, Leo Gkekos, Emelie Karlsson, Anna L.V. Johansson, Per Karlsson, Anne Andersson, Antonios Valachis, Irma Fredriksson, Theodoros Foukakis, Johan Hartman, Breast Cancer Research, online 13 August 2026, doi: 10.1186/s13058-026-02366-w.