A study presented at the European Breast Cancer Conference has found while women from poorer backgrounds are more likely to have worse outcomes, there are more factors involved beyond the likelihood these women received late cancer diagnoses.
Esther Bastiaannet, MD, Leiden University Medical Center in the Netherlands, and colleagues studied 127,500 women diagnosed with breast cancer between 1995 and 2005 in the Netherlands. The data on those women were linked to data from the Netherlands Institute for Social Research, which tracks socioeconomic data by postal code.
The researchers found that in addition to there being an association between tumor size and socioeconomic status, that there was also a statistically significant association between survival and socioeconomic status, even after adjusting for factors like age, grade and state of tumors, year of diagnosis and treatment.
Taking into consideration survival (the number of deaths in the population by any cause) and relative survival (the ratio of between survival of breast cancer patients compared to the survival expected from the overall population), they both declined with lower socioeconomic status.
According to the researchers, 10 years after diagnosis, overall survival was 65 percent for highest socioeconomic status patients compared wtih 58 percent for the lowest socioeconomic status patients; relative survival was 79 percent for the highest socioeconomic status patients, compared with 74 percent for the lowest socioeconomic status patients.
"An increase of five percent in relative survival [from 74-79 percent] may look small, but these differences are significant to the prognosis of patients with breast cancer," said Bastiaannet. "The differences were statistically significant, even after adjustment for age, year of diagnosis, grade and stage of the tumour and treatment. The increased risk of death for the lowest socioeconomic status group was a fifth higher when compared to the risk for the highest socioeconomic status group.
According to Bastiaannet, more advanced cancer at diagnosis for patients with a lower socioeconomic status only partly explains their lower survival rates.
At present, it is not known for certain what factors might be contributing to the higher risk of death from breast cancer among women from poorer backgrounds. "Lifestyle factors, such as smoking, may play a role," said Bastiaannet. "Access to early detection, treatment that could be influenced by other health problems, and other, as yet, unknown factors all may be involved as well."