The mortality risk from breast cancer is doubled for patients with high heterogeneity of the oestrogen receptor within the same tumour, according to Swedish researchers.
The Swedish and American researchers say that this increased risk of death over a span of 25 years is independent of other known tumour markers. It also applies to Luminal A breast cancer, a subtype of the disease that has a generally good prognosis, they say.
Writing in The Journal of the National Cancer Institute, the researchers say that women who develop oestrogen-receptor-positive breast cancer face a long-term risk of dying of the disease.
The researchers studied 593 patients diagnosed with post-menopausal oestrogen-receptor-positive breast cancer between 1976 and 1990. All had been treated with tamoxifen or not treated with systemic therapy after surgery.
Linda Lindström, researcher at the Department of Biosciences and Nutrition, Karolinska Institutet, said: “Our study shows that patients with high intra-tumour heterogeneity of the oestrogen receptor were twice as likely to die up to 25 years after their diagnoses as compared to patients with low heterogeneity and this was independent of whether or not they’d received tamoxifen and of other known tumour markers.
“Patients with Luminal A breast cancer and high intra-tumour heterogeneity of the oestrogen receptor were also twice as likely to die from the disease.
“This is interesting given that patients with Luminal A breast cancer subtype are generally thought to have a good prognosis. We believe that if validated, these new findings should be useable within the near future."
Lindström L, Yau C, Czene K et al. Intratumor Heterogeneity of the Estrogen Receptor and the Long-term Risk of Fatal Breast Cancer. Journal of The National Cancer Institute January 2018; doi: 10.1093/jnci/djx270.
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