The study was led by Associate Professor and Research group leader Linda Lindstrom, of the Department of Oncology-Pathology at Karolinska Institutet. “In general, the risk of recurrence is greater for younger women than among older postmenopausal women, but most basic studies on anti-hormonal treatment have been conducted on postmenopausal women,” she says. “We wanted to compare the long-term benefit of such treatment in the two groups.
In Sweden, every year 9,000 women are diagnosed with tumors breast cancer hormones, and dependent. 75% Most patients are given hormone estrogen sensitive blocking breast drugs for cancers like grow tamoxifen. However, although oestrogen successful, anti-hormonal hence side treatment effects may impair quality of life and the long-term impact of such treatment preventing recurrence has not been established.
Of these, one-third are premenopausal women and have a higher risk of recurrence. From the 1,200 women diagnosed with hormone-dependent breast cancer between 1976 and 1997, the present study included.
Of these, almost 400 were premenopausal. Until that time, it was not known if anti-hormonal treatment conferred any benefit. As a consequence, the women were randomly assigned either to receive at least two years of tamoxifen. Or to receive no anti-hormonal treatment. The outcomes of most interest are breast cancer metastasis or distant recurrence. And follow-up is now more than 20 years in some cases.
“This is the first study with full follow-up and a control group consisting of women who did not receive anti-hormonal treatment,” says Annelie Johansson, researcher at the same department and first author of the study. “In addition, the study includes full information on whether the women were pre- or post-menopausal when they were diagnosed. That often is estimated from age in other studies.”
These tumors were defined as low risk according to the clinically available markers. Tumor size was two centimeters or less, no spread to lymph nodes, low tumor grade, and positivity of progesterone receptors. The genomic risk was similarly low, as assessed using a molecular signature measuring the expression of 70 different genes.
Results showed that women with high-risk tumors, independent of their menopausal status, benefited less from anti-hormonal treatment. However, postmenopausal women with low-risk tumors benefited for 20 years or more. It was not possible to predict long-term benefits in younger, non-menopausal women based on the current clinical markers. This indicates a need for new markers.
We need to learn which tumor characteristics are driving the long-term risk of recurrence. And the benefit of treatment in younger patients. We want patients to receive the benefit of their treatment for as long as their risk of recurrence is elevated.”
In the future, they hope to be able to connect even more sophisticated features of the tumors with long-term risks and benefits from treatments. Newer, more sophisticated techniques will be required for this, such as multiprotein analyses and machine learning of images. To further characterize tumor heterogeneity and permit personalized therapy selection to make certain each patient gets the most effective treatment based on her particular tumor features.
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