Improved Breast Cancer Survival Rates Linked To Smaller Tumors
- Date:
- August 9, 2005
- Source:
- John Wiley & Sons, Inc.
- Summary:
- A new study finds that the size of newly diagnosed breast cancers has shifted towards smaller tumors, even within conventional cancer stage categories, and that this shift accounts for a proportion of the improvement seen in breast cancer survival over the last 30 years.
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A new study finds that the size of newly diagnosed breast cancers hasshifted towards smaller tumors, even within conventional cancer stagecategories, and that this shift accounts for a proportion of theimprovement seen in breast cancer survival over the last 30 years. Theauthors of the report say that failure to account for this shift intumor size can lead to overestimation of the impact of treatmentadvances. The study is published in the September 15, 2005 issue ofCANCER (http://www.interscience.wiley.com/cancer-newsroom), a peer-reviewed journal of the American Cancer Society.
Great strides in breast cancer survival have been made over the last30 years, overall and within cancer stages, coinciding with advances intreatment and with increased use of screening mammography. However, ifimportant prognostic factors have also changed over time, then observedimprovements in breast cancer survival may be a result of such changesand of improvements in treatment. The authors studied changes in tumorsize because it is a strong predictor of breast cancer prognosis and itis a straightforward, reliably evaluated, consistently availablemeasure.
Elena B. Elkin, Ph.D. of the Memorial Sloan-Kettering CancerCenter in New York and her colleagues reviewed data on early-stagebreast cancers from the Surveillance, Epidemiology and End Results(SEER) program to look for trends in tumor size and explore how thosetrends might impact survival rates. SEER is a population-based cancerregistry system that collects and monitors data on cancers diagnosed incertain areas of the U.S.
Among localized and regional breast cancers, the size of newlydiagnosed tumors decreased significantly from 1975 through 1999. Whilebreast cancer survival rates improved during this time, adjusting forthe changes in tumor size diminished the magnitude of the survivalincreases within each stage category. When the researchers comparedfive-year cancer survival rates in women diagnosed 1995-1999 withsurvival rates in women diagnosed 1975-1979, they found that the shifttoward smaller tumors explained 61 percent of the survival increase inlocalized breast cancer and 28 percent of the survival increase inregional breast cancer.
"Failure to adequately control for this [within-stage tumorsize] shift leads to inflated estimates of the impact of secularchanges in treatment on stage-specific survival," conclude the study'sauthors. They add, "size-standardization is a refinement ... thatgreatly improves our ability to interpret ... trends in breast cancersurvival."
Article: "The Effect ofChanges in Tumor Size on Breast Carcinoma Survival in the U.S.:1975-1999," Elena B. Elkin, Clifford Hudis, Colin B. Begg, DeborahSchrag, CANCER; Published Online: August 8, 2005 (DOI:10.1002/cncr.21285); Print Issue Date: September 15, 2005.
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