"Smaller tumors, not just treatment,
improving breast cancer survival"
The following information is excerpted from an article by the Associated Press published in The Baltimore Sun, Monday, August 8, 2005. It has been edited for clarity and length.
Much of the improvement in breast cancer survival rates in recent years is because the average tumor is smaller, not just because treatments are so much better, a wide-ranging new study has found.
Examining 25 years of cancer records nationwide, researchers concluded that smaller tumor size accounted for 61% of the improvement in survival when cancer had not spread beyond the breast, and 28% when it had spread just a little. For women 65 and older with early-stage tumors, the shift in size accounted for virtually all of the improvement in survival.
Survival has increased, but experts have argued over how much of this is because of better drugs or because tumors are being found at earlier stages. Two thirds of breast cancers today are diagnosed at the local stage, when they're still confined to the breast; in the 1970s, only half were.
However, this is the largest study in American women to look at size within those stages.
The study wasn't designed to determine the value of mammograms or treatments. But it implies much about the value of early detection. Use of mammograms has increased drastically in recent years and is the chief reason that cancers today are found sooner and smaller than they were in years past.
The study was conducted by doctors at Memorial Sloan-Kettering Cancer Center in New York and used a Federal government database that includes nine cancer registries covering 10% of the U.S. population. More than 265,000 breast tumors were analyzed.
The number of local-stage breast cancers that were smaller than 1 cm rose from less than 10% from 1975 to 1979 to 25% from 1995 through 1999.
Two thirds of breast cancers today are diagnosed at a local stage, when they're still confined to the breast; in the 1970s, only half were. For women with local-stage breast cancers, survival rose from nearly 91% to more than 97%. Improvements in treatment results account for 2% of this increase while 4% of the increased survival was due to tumors being detected at a smaller size.
For regional cancers (having spread to the lymph nodes only), survival rose from 68% to about 80%. Treatment improvement accounted for 4% of this increase while 8% of the survival increase was due to finding tumors in a smaller size.
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