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About 1 in 5 breast cancer survivors who have completed 5 years of adjuvant therapy suffer a recurrence within the 10 years after their treatment, according to a recent study in the Journal of the National Cancer Institute.

The study offers women a detailed picture of how likely they are to face a recurrence further down the road.

Abeena Brewster, MD, and colleagues at the M.D. Anderson Cancer Center in Houston, Texas looked at the risk of recurrence in nearly 3,000 women with stage I, II, and III breast cancer who were treated at the center from 1985 through 2001. All of the women had neoadjuvant or adjuvant chemotherapy or hormonal therapy.

For the overall group, recurrence rates were 11% at 5 years and 20% at 10 years after completion of adjuvant therapy.

Brewster and colleagues reported that recurrence risk increased with higher stage. Five-year recurrence rates were 7%, 11%, and 13% for women with stages I, II, and II disease, respectively.

Recurrence rates also varied by grade, which is a description of how the breast cancer cells look under a microscope. Breast cancer cells are graded on a scale from 1 to 3 – the higher the grade, the more abnormal the cells look and more likely they are to grow quickly. Five-year recurrence rates for women with grades 1, 2, and 3 tumors were 14%, 13%, and 9%, respectively.

The risk of recurrence seemed to be affected by the hormone receptor status of the cancers, as well. The 5-year recurrence rate was 7% for women with hormone receptor-negative tumors and 13% for those with hormone receptor-positive disease.

Women with higher grade tumors and those with hormone receptor-negative cancers tend to have a worse prognosis than those with lower grade or hormone receptor-positive cancers, so it might seem surprising that the recurrence risks in these groups were lower in this study. But this is likely because some women in these groups had already had recurrences while still being treated, which would have kept them out of the study.

According to Len Lichtenfeld, MD, American Cancer Society deputy chief medical officer, "more women with hormone negative and higher grade cancers may have had very early relapses, and if they made it through the first 5 years after diagnosis (a time period not included in this study) they did better in the long term. In other words, those who did not relapse within 5 years after diagnosis may have been 'selected' to have a better long-term outlook."

Brewster and colleagues noted some important limitations to this study. Most of the patients were treated before aromatase inhibitors were widely used in adjuvant therapy, and before trastuzumab (Herceptin) was introduced as adjuvant therapy.

According to Dr. Lichtenfeld, this study has a few important take-home messages.

First, adjuvant therapy does not completely remove the risk of late cancer recurrence, even for women with low grade/low stage tumors. And although recent advances in therapy can be expected to reduce the risk of late recurrence below that reported in this study, clinicians and patients still need to remain aware of this problem and researchers need to consider this a high priority for further studies.

For more information, see Detailed Guide: Breast Cancer.

Citation: "Residual Risk of Breast Cancer Recurrence 5 Years After Adjuvant Therapy." Published in the August 12, 2008 online issue of the Journal of the National Cancer Institute. First author: Abeena M. Brewster, MD.