Breast cancer patients who receive five years of treatment have an increased risk for disease recurrence even 15 years after they were first diagnosed, new American research suggests.

Researchers at the University of Texas M.D. Anderson Cancer Center found that 20 per cent of breast cancer patients who received five years of chemotherapy, hormone therapy or other treatments relapsed 10 years after they stopped treatment.

They also found that patients whose tumours were more advanced at the time of diagnosis were more likely to relapse.

The findings are published in the online edition of the Journal of the National Cancer Institute.

Despite the findings, the researchers said that women who have their tumours surgically removed and receive chemotherapy or hormone therapy, or both, still have lower relapse rates than women who do not receive these treatments.

Researchers, led by Dr. Abenaa Brewster of the University of Texas, studied breast cancer recurrence rates among more than 2,800 patients who were treated between 1985 and 2001.

They found that the risk of relapse among patients five years after they stopped treatment was:

  • seven per cent among those with stage one breast cancer.
  • 11 per cent among those with stage two breast cancer.
  • 13 per cent among those with stage three breast cancer.

The researchers concluded that "more research is needed to identify host and tumour characteristics that are associated with late breast cancer recurrences to individualize" treatment.

Abstract:

Residual Risk of Breast Cancer Recurrence 5 Years After Adjuvant Therapy

Abenaa M. Brewster, Gabriel N. Hortobagyi, Kristine R. Broglio, Shu-Wan Kau, Cesar A. Santa-Maria, Banu Arun, Aman U. Buzdar, Daniel J. Booser, Vincente Valero, Melissa Bondy, Francisco J. Esteva

There is limited prognostic information to identify breast cancer patients who are at risk for late recurrences after adjuvant or neoadjuvant systemic therapy (AST). We evaluated the residual risk of recurrence and prognostic factors of 2838 patients with stage I - III breast cancer who were treated with AST between January 1, 1985, and November 1, 2001, and remained disease free for 5 years. Residual recurrence-free survival was estimated from the landmark of 5 years after AST to date of first recurrence or last follow-up using the Kaplan - Meier method. The log-rank test (two-sided) was used to compare groups. Residual recurrence-free survival rates at 5 and 10 years were 89% and 80%, respectively, and 216 patients developed a recurrence event. The 5-year residual risks of recurrence for patients with stage I, II, and III cancers were 7% (95% confidence interval [CI] = 3% to 15%), 11% (95% CI = 9% to 13%), and 13% (95% CI = 10% to 17%), respectively ( P = .02). In multivariable analysis, stage, grade, hormone receptor status, and endocrine therapy were associated with late recurrences. Breast cancer patients have a substantial residual risk of recurrence, and selected tumor characteristics are associated with late recurrences.