Study quantifies risk of breast cancer recurrence

 

Figure  . A new study identifies factors associated with breast cancer recurrence after adjuvant therapy. This graph, created with the National Cancer Institute's Fast Stats application, shows relative survival rates by survival time for women with breast cancer, all ages, 1998–2004.

A study in the August 12 online issue of the Journal of the National Cancer Institute (2008; 100:1179–1183) finds about 1 in 5 breast cancer survivors who had completed 5 years of adjuvant therapy suffered a recurrence in the 10 years after treatment was complete (between 5 and 15 years after the initial diagnosis).

Abeena Brewster, MD, and colleagues from the MD Anderson Cancer Center in Houston, Texas, reviewed recurrence-free survival of 2,838 women with Stage I, II, or 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% and 20%, respectively, 5 and 10 years after completion of adjuvant therapy.

Brewster, an Assistant Professor in MD Anderpson Cancer Center's Department of Clinical Cancer Prevention, and colleagues reported that recurrence risk increased with higher stage; 5-year recurrence-free survival rates were 93.1% [95% confidence interval (CI) 84.9%, 96.9%], 88.8% [95% CI 86.5%, 90.7%], and 87.3% [95% CI 83.4%, 90.3%] for women with stages I, II, and II disease, respectively. While few clinicians will be surprised by the unfavorable prognostic effect of higher stage, findings related to tumor grade and hormone receptor status might initially strike some as counterintuitive.

Five-year recurrence-free survival rates for women with grades 1, 2, and 3 tumors were 85.7% [95% CI 69.6%, 93.6%], 87.4% [95% CI 84.4%, 89.9%], and 91.4 [95% CI 88.9%, 93.3%], respectively. Similarly, the 5-year recurrence-free survival rate was 92.9% [95% CI 89.7%, 95.1%] for women with hormone receptor-negative tumors and 87.0% [95% CI 84.3%, 89.2%] for those with hormone receptor-positive disease.

The likely reason, according to Len Lichtenfeld, MD, American Cancer Society (ACS) Deputy Chief Medical Officer, is that, “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 (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, the most important of which is that most of the patients were treated before third-generation aromatase inhibitors were widely used in adjuvant therapy and before trastuzumab was introduced as adjuvant therapy.

The main take-home messages, according to Lichtenfeld, are that adjuvant therapy does not completely remove the risk of late cancer recurrence, even for women with low-grade/low-stage tumors, and that although recent advances in therapy (adjuvant use of trastuzumab and use of aromatase inhibitors initially and after tamoxifen) 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 basic and clinical investigation.