New research has found that even after 5 years of systemic therapy, breast cancer patients still have a substantial risk of the disease recurring.
Among breast cancer patients who were cancer-free five years after beginning systemic therapy, 89 percent remained recurrence-free at five years (approximately 10 years after a woman's initial diagnosis) and 80 percent remained recurrence free at 10 years (approximately 15 years after diagnosis).
Women who receive chemotherapy, hormone therapy, or both, in addition to surgery, have a higher rate of relapse-free survival than women who do not receive adjuvant or neoadjuvant therapy.
However, even following systemic therapy, breast cancer survivors remain at risk for relapse and few studies have evaluated the magnitude of that risk or the patient and tumour characteristics that are associated with the disease recurring.
A study by Dr. Abenaa Brewster from the University of Texas in Houston examined the recurrence rate in 2,838 breast cancer patients who had been treated between 1985 and 2001 at the cancer center.
Dr. Brewster and colleagues found that by 28 months, 216 women developed recurrent breast cancer and the five-year risk of relapse for women with stage I disease was 7 percent, 11 percent for women with stage II disease, and 13 percent for women with stage III disease.
They say tumour grade, hormone receptor status, and endocrine therapy were all significantly linked with a risk of recurrence.
The researchers say the increased risk of disease recurrence after five years of therapy for women with hormone receptor positive cancer indicates an area of unmet clinical need and while there are risk-reduction options for postmenopausal women who have completed five years of tamoxifen therapy, none exist for premenopausal women; they suggest new strategies need to be developed for these women to further reduce their risk.
The researchers say their study demonstrates that patients with early stage breast cancer who are disease free at five years after adjuvant systemic therapy have a substantially increased residual risk of recurrence.
The study is published in the online issue of the Journal of the National Cancer Institute.