Washington, Aug 13 : A new study has found that breast cancer survivors continue to have a substantial risk of disease recurrence after five years of systemic therapy.
Few studies have evaluated the magnitude of that risk or the patient and tumour characteristics that are associated with disease recurrence.
In the current study, Abenaa Brewster, M.D., of the University of Texas M. D. Anderson Cancer Center in Houston and colleagues examined the recurrence rate in 2,838 breast cancer patients who had been treated between 1985 and 2001 at the cancer center and were included in the center's tumour registry.
To find out the magnitude of residual risk following adjuvant therapy, which might include five years of hormone therapy, the researchers examined what happened to the women five years after the start of treatment.
After a median follow-up period of 28 months, 216 women developed recurrent disease.
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.
Tumour grade, hormone receptor status, and endocrine therapy were all statistically significantly associated with risk of recurrence.
The increased risk of disease recurrence after five years of therapy for women with hormone receptor positive cancer points to an area of unmet clinical need.
While there are risk-reduction options for postmenopausal women who have completed five years of tamoxifen therapy, none exist for premenopausal women.
New strategies need to be developed for these women to further reduce their risk.
"In conclusion, this 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 authors said.
The study is published in the August 12 online issue of the Journal of the National Cancer Institute.