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Women at risk of breast cancer returning if they stop therapy

Women who have had breast cancer and stop endocrine therapy after five years may have a risk of the cancer returning up to 20 years after their orginal diagnonsis,, according to researchers

Women who have had breast cancer and stop endocrine therapy after five years may be at risk of it returning up to 20 years after their original diagnosis, according to researchers.

A mammogram. Picture: iStock

Standard treatment for oestrogen receptor-positive (ER-positive) breast cancer includes five years of the endocrine-based treatments tamoxifen or aromatase inhibitors, both of which are a taken daily as a tablet.

The Early Breast Cancer Trialists' Collaborative Group, which includes researchers from the University of Oxford, analysed data from 88 clinical trials over 20 years involving over 60,000 women with ER-positive breast cancer.

The patients had all received endocrine therapy for five years and were free of cancer when they stopped therapy.

Highest risk

However, a number of these women saw the cancer spread throughout their body as late as 20 years after the initial diagnosis, according to the study.

The highest risk of the cancer coming back was for those who originally had large tumours and cancer that had spread to four or more lymph nodes.

These women had a 40% risk of a distant cancer returning over the next 15 years. Women with small, low-grade cancers and no spread to the lymph nodes had a much lower 10% risk of cancer spreading distantly during the following 15 years.

Researchers suggest that women with ER-positive breast cancer may wish to consider receiving anti-oestrogen therapy beyond five years.

Hongchao P et al (2017) 20-Year Risks of Breast-Cancer Recurrence after Stopping Endocrine Therapy at 5 Years. New England Journal of Medicine. doi: 10.1056/NEJMoa1701830

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