Low Risk for Breast Cancer Recurrence 5 and 10 Years Post-Therapy

The amount of information available to help identify women at risk for late recurrences of breast cancer is limited. A new study suggests that 10 and 15 years after completing adjuvant therapy, women retain a low risk for breast cancer recurrence.

The amount of information available to help identify women at risk for late recurrences of breast cancer is limited. A new study suggests that 10 and 15 years after completing adjuvant therapy, women retain a low risk for breast cancer recurrence.

“The general practice in oncology is to follow patients for 5 years and if women remain cancer-free, that is the time they usually go back to their internists for follow-up,” said lead author Abenaa Brewster, MD, MHS, assistant professor of clinical cancer prevention at M. D. Anderson Cancer Center (MDACC) in Houston. “One of the questions I get asked a lot at that point concerns their chances of still getting breast cancer in the future.” Dr. Brewster and colleagues hope to quantify the residual risks for cancer survivors and their physicians.

Patients included in this study were selected retrospectively from the Protocol Data Management Systems (PDMS) and Breast Cancer Management Systems (BCMS) databases at MDACC between January 1, 1985 and November 1, 2001. Prior to 1997, all patients in the study were enrolled in systemic treatment clinical trials because nonprotocol patients were not included in the database before that time.

Patients were eligible if they had a diagnosis of breast cancer (stage I, II, or III), had undergone surgery at MDACC, received adjuvant systemic therapy (AST) consisting of adjuvant or neoadjuvant chemotherapy and/or endocrine therapy, and survived 5 years from the start of AST. Of the 3064 patients meeting selection criteria, 226 were excluded for various reasons. The primary end point was time to recurrence. Residual recurrence-free survival was calculated from the landmark of 5 years from the start of AST to the date of first recurrence or last follow-up.

Survival rates at 5 and 10 years after entry into the study (10 and 15 years after AST) were 89% and 80%, respectively, with cancer recurrence in 216 patients. The 5-year residual risks were 7% for women with an initial diagnosis of stage I breast cancer, 11% for those with a stage II diagnosis, and 13% for women with a stage III diagnosis. Multivariate analysis shows that stage, grade, hormone receptor status, and endocrine therapy were all associated with late recurrences.

“A lot of our patients…think their chances of recurrence are fairly high,” said Dr. Brewster. “Oncologists can now tell these women that their chances of recurrence are fairly low. In women already cancer-free for 5 years, I would hope that this is reassuring.”

Dr. Brewster stressed that these results do not apply to all women. “The patients we studied were women diagnosed and treated between 1985 and 2001,” she explained. “Since that time, we have had some tremendous advances in the treatment of breast cancer. We don’t know if these numbers apply to women who are getting very advanced treatments.” She suggested that women getting cutting-edge treatments might have an even lower risk of late recurrence than the study indicates.

Julie Means-Powell, MD, assistant professor of medicine at Vanderbilt Medical Center in Nashville praised the study and said it produced some interesting results. Dr. Means-Powell noted that the study tells oncologists that patients with estrogen-positive tumors are at risk for late recurrence, that there is a need for additional adjuvant endocrine therapy for some pre- and post-menopausal women between 5 and 10 years after the start of AST, and oncologists need a better way to identify those patients likely to have cancer recurrence.

“I don’t think there were any big surprises in the study,” Dr. Means-Powell said. “Where the article is important is in showing that pre-menopausal women after 5 years of tamoxifen are still at risk for recurrence during the next 5 years.” She said that the lack of a standard therapy to addresses this issue is evidence of a gap in what we know about breast cancer recurrence. “Addressing this issue in the future should be a focus of clinical trials.”

Several ongoing clinical trials are examining the role of aromatase inhibitors from posttreatment year 5 to year 10 in postmenopausal women. The National Cancer Institute of Canada Clinical Trials Group MA 17 examined the efficacy of letrozole started after 5 years of tamoxifen in postmenopausal women with hormone-receptor positive early stage breast cancer and saw an improvement in disease-free survival.

Brewster AM, et al. Residual risk of breast cancer recurrence 5 years after adjuvant therapy. J Natl Cancer Inst. 2008;100:1-5.

Kurt Ullman is a freelance health and medical writer based out of Indianapolis.

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